Cutis

Drug rash with eosinophilia and systemic symptoms (DRESS syndrome), also known as drug-induced hypersensitivity syndrome, is an uncommon severe systemic hypersensitivity drug reaction. It is estimated to occur in 1 in every 1000 to 10,000 drug exposures.¹ It can affect patients of all ages and typically presents 2 to 6 weeks after exposure to a culprit medication. Classically, DRESS syndrome presents with often widespread rash, facial edema, systemic symptoms such as fever, lymphadenopathy, and evidence of visceral organ involvement. Peripheral blood eosinophilia is frequently but not universally observed.^1,2

Even with proper management, reported DRESS syndrome mortality rates worldwide are approximately 10%² or higher depending on the degree and type of other organ involvement (eg, cardiac).³ Beyond the acute manifestations of DRESS syndrome, this condition is unique in that some patients develop late-onset sequelae such as myocarditis or autoimmune conditions even years after the initial cutaneous eruption.⁴ Therefore, longitudinal evaluation is a key component of management.

The clinical myths and pearls presented here highlight some of the commonly held assumptions regarding DRESS syndrome in an effort to illuminate subtleties of managing patients with this condition (Table).

Myth: DRESS syndrome may only be diagnosed when the clinical criteria satisfy one of the established scoring systems.

Patients with DRESS syndrome can have heterogeneous manifestations. As a result, patients may develop a drug hypersensitivity with biological behavior and a natural history compatible with DRESS syndrome that does not fulfill published diagnostic criteria.⁵ The syndrome also may reveal its component manifestations gradually, thus delaying the diagnosis. The terms mini-DRESS and skirt syndrome have been employed to describe drug eruptions that clearly have systemic symptoms and more complex and pernicious biologic behavior than a simple drug exanthema but do not meet DRESS syndrome criteria. Ultimately, it is important to note that in clinical practice, DRESS syndrome exists on a spectrum of severity and the diagnosis remains a clinical one.

Pearl: The most commonly involved organ in DRESS syndrome is the liver.

Liver involvement is the most common visceral organ involved in DRESS syndrome and is estimated to occur in approximately 45.0% to 86.1% of cases.^6,7 If a patient develops the characteristic rash, peripheral blood eosinophilia, and evidence of liver injury, DRESS syndrome must be included in the differential diagnosis.

Hepatitis presenting in DRESS syndrome can be hepatocellular, cholestatic, or mixed.^6,7 Case series are varied in whether the transaminitis of DRESS syndrome tends to be more hepatocellular⁸ or cholestatic.⁷ Liver dysfunction in DRESS syndrome often lasts longer than in other severe cutaneous adverse drug reactions, and patients may improve anywhere from a few days in milder cases to months to achieve resolution of abnormalities.^6,7 Severe hepatic involvement is thought to be the most notable cause of mortality.⁹

Pearl: New-onset proteinuria, hematuria, and sterile pyuria indicate acute interstitial nephritis that may be associated with DRESS syndrome.

Acute interstitial nephritis (AIN) is a drug-induced form of acute kidney injury that can co-occur with DRESS syndrome. Acute interstitial nephritis can present with some combination of acute kidney injury, morbilliform eruption, eosinophilia, fever, and sometimes eosinophiluria. Although AIN can be distinct from DRESS syndrome, there are cases of DRESS syndrome associated with AIN.¹⁰ In the correct clinical context, urinalysis may help by showing new-onset proteinuria, new-onset hematuria, and sterile pyuria. More common causes of acute kidney injury such as prerenal etiologies and acute tubular necrosis have a bland urinary sediment.

Myth: If the eruption is not morbilliform, then it is not DRESS syndrome.

The most common morphology of DRESS syndrome is a morbilliform eruption (Figure 1), but urticarial and atypical targetoid (erythema multiforme–like) eruptions also have been described.⁹ Rarely, DRESS syndrome secondary to use of allopurinol or anticonvulsants may have a pustular morphology (Figure 2), which is distinguished from acute generalized exanthematous pustulosis by its delayed onset, more severe visceral involvement, and prolonged course.¹¹

Another reported variant demonstrates overlapping features between Stevens-Johnson syndrome/toxic epidermal necrolysis and DRESS syndrome. It may present with mucositis, atypical targetoid lesions, and vesiculobullous lesions.¹² It is unclear whether this reported variant is indeed a true subtype of DRESS syndrome, as Stevens-Johnson syndrome/toxic epidermal necrolysis may present with systemic symptoms, lymphadenopathy, hepatic, renal, and pulmonary complications, among other systemic disturbances.¹²

Pearl: Facial edema noted during physical examination is an important clue of DRESS syndrome.

Perhaps the most helpful findings in the diagnosis of DRESS syndrome are facial edema and anasarca (Figure 3), as facial edema is not a usual finding in sepsis. Facial edema can be severe enough that the patient’s features are dramatically altered. It may be useful to ask family members if the patient’s face appears swollen or to compare the current appearance to the patient’s driver’s license photograph. An important complication to note is laryngeal edema, which may complicate airway management and may manifest as respiratory distress, stridor, and the need for emergent intubation.¹³

Myth: Patients who have had an allergic reaction to sulfonamide antibiotics will have a cross-reaction to nonantibiotic sulfonamides.

A common question is, if a patient has had a prior allergy to sulfonamide antibiotics, then are nonantibiotic sulfones such as a sulfonylurea, thiazide diuretic, or furosemide likely to cause a a cross-reaction? In one study (N=969), only 9.9% of patients with a prior sulfone antibiotic allergy developed hypersensitivity when exposed to a nonantibiotic sulfone, which is thought to be due to an overall increased propensity for hypersensitivity rather than a true cross-reaction. In fact, the risk for developing a hypersensitivity reaction to penicillin (14.0% [717/5115]) was higher than the risk for developing a reaction from a nonantibiotic sulfone among these patients.¹⁴ This study bolsters the argument that if there are other potential culprit medications and the time course for a patient’s nonantibiotic sulfone is not consistent with the timeline for DRESS syndrome, it may be beneficial to look for a different causative agent.

Pearl: Vancomycin is an important cause of DRESS syndrome.

Guidelines for treating endocarditis and osteomyelitis caused by methicillin-resistant Staphylococcus aureus infection recommend intravenous vancomycin for 4 to 6 weeks.¹⁵ This duration is within the relevant time frame of exposure for the development of DRESS syndrome de novo.

One case series noted that 37.5% (12/32) of DRESS syndrome cases in a 3-year period were caused by vancomycin, which notably was the most common medication associated with DRESS syndrome.¹⁶ There were caveats to this case series in that no standardized drug causality score was used and the sample size over the 3-year period was small; however, the increased use (and misuse) of antibiotics and perhaps increased recognition of rash in outpatient parenteral antibiotic therapy clinics may play a role if vancomycin-induced DRESS syndrome is indeed becoming more common.

Myth: Myocarditis secondary to DRESS syndrome will present with chest pain at the time of the cutaneous eruption.

Few patients with DRESS syndrome–associated myocarditis actually are symptomatic during their hospitalization.⁴ In asymptomatic patients, the primary team and consultants should be vigilant for the potential of subclinical myocarditis or the possibility of developing cardiac involvement after discharge, as myocarditis secondary to DRESS syndrome may present any time from rash onset up to 4 months later.⁴ Therefore, DRESS patients should be especially attentive to any new cardiac symptoms and notify their provider if any develop.

Although no standard cardiac screening guidelines exist for DRESS syndrome, some have recommended that baseline cardiac screening tests including electrocardiogram, troponin levels, and echocardiogram be considered at the time of diagnosis.⁵ If any testing is abnormal, DRESS syndrome–associated myocarditis should be suspected and an endomyocardial biopsy, which is the diagnostic gold standard, may be necessary.⁴ If the cardiac screening tests are normal, some investigators recommend serial outpatient echocardiograms for all DRESS patients, even those who remain asymptomatic.¹⁷ An alternative is an empiric approach in which a thorough review of systems is performed and testing is done if patients develop symptoms that are concerning for myocarditis.

Pearl: Steroids are not the only treatment used to control DRESS syndrome.

A prolonged taper of systemic steroids is the first-line treatment of DRESS syndrome. Steroids at the equivalent of 1 to 2 mg/kg daily (once or divided into 2 doses) of prednisone typically are used. For severe and/or recalcitrant DRESS syndrome, 2 mg/kg daily (once or divided into 2 doses) typically is used, and less than 1 mg/kg daily may be used for mini-DRESS syndrome.

Clinical improvement of DRESS syndrome has been demonstrated in several case reports with intravenous immunoglobulin, cyclosporine, cyclophosphamide, mycophenolate mofetil, and plasmapheresis.^18-21 Each of these therapies typically were initiated as second-line therapeutic agents when initial treatment with steroids failed. It is important to note that large prospective studies regarding these treatments are lacking; however, there have been case reports of acute necrotizing eosinophilic myocarditis that did not respond to the combination of steroids and cyclosporine.^4,22

Although there have been successful case reports using intravenous immunoglobulin, a 2012 prospective open-label clinical trial reported notable side effects in 5 of 6 (83.3%) patients with only 1 of 6 (16.6%) achieving the primary end point of control of fever/symptoms at day 7 and clinical remission without steroids on day 30.²³

Pearl: DRESS patients need to be monitored for long-term sequelae such as autoimmune disease.

Several autoimmune conditions may develop as a delayed complication of DRESS syndrome, including autoimmune thyroiditis, systemic lupus erythematosus, type 1 diabetes mellitus, and autoimmune hemolytic anemia.^24-26 Incidence rates of autoimmunity following DRESS syndrome range from 3% to 5% among small case series.^24,25

Autoimmune thyroiditis, which may present as Graves disease, Hashimoto thyroiditis, or painless thyroiditis, is the most common autoimmune disorder to develop in DRESS patients and appears from several weeks to up to 3 years after DRESS.²⁴ Therefore, all DRESS patients should be monitored longitudinally for several years for signs or symptoms suggestive of an autoimmune condition.^5,24,26

Because no guidelines exist regarding serial monitoring for autoimmune sequelae, it may be reasonable to check thyroid function tests at the time of diagnosis and regularly for at least 2 years after diagnosis.⁵ Alternatively, clinicians may consider an empiric approach to laboratory testing that is guided by the development of clinical symptoms.

Pearl: Small cases series suggest differences between adult and pediatric DRESS syndrome, but there are no large studies in children.

Small case series have suggested there may be noteworthy differences between DRESS syndrome in adults and children. Although human herpesvirus 6 (HHV-6) positivity in DRESS syndrome in adults may be as high as 80%, 13% of pediatric patients in one cohort tested positive for HHV-6, though the study size was limited at 29 total patients.²⁷ In children, DRESS syndrome secondary to antibiotics was associated with a shorter latency time as compared to cases secondary to nonantibiotics. In contrast to the typical 2- to 6-week timeline, Sasidharanpillai et al²⁸ reported an average onset 5.8 days after drug administration in antibiotic-associated DRESS syndrome compared to 23.9 days for anticonvulsants, though this study only included 11 total patients. Other reports have suggested a similar trend.²⁷

The role of HHV-6 positivity in pediatric DRESS syndrome and its influence on prognosis remains unclear. One study showed a worse prognosis for pediatric patients with positive HHV-6 antibodies.²⁷ However, with such a small sample size—only 4 HHV-6–positive patients of 29 pediatric DRESS cases—larger studies are needed to better characterize the relationship between HHV-6 positivity and prognosis.

Drug rash with eosinophilia and systemic symptoms (DRESS syndrome), also known as drug-induced hypersensitivity syndrome, is an uncommon severe systemic hypersensitivity drug reaction. It is estimated to occur in 1 in every 1000 to 10,000 drug exposures.¹ It can affect patients of all ages and typically presents 2 to 6 weeks after exposure to a culprit medication. Classically, DRESS syndrome presents with often widespread rash, facial edema, systemic symptoms such as fever, lymphadenopathy, and evidence of visceral organ involvement. Peripheral blood eosinophilia is frequently but not universally observed.^1,2

Even with proper management, reported DRESS syndrome mortality rates worldwide are approximately 10%² or higher depending on the degree and type of other organ involvement (eg, cardiac).³ Beyond the acute manifestations of DRESS syndrome, this condition is unique in that some patients develop late-onset sequelae such as myocarditis or autoimmune conditions even years after the initial cutaneous eruption.⁴ Therefore, longitudinal evaluation is a key component of management.

The clinical myths and pearls presented here highlight some of the commonly held assumptions regarding DRESS syndrome in an effort to illuminate subtleties of managing patients with this condition (Table).

Myth: DRESS syndrome may only be diagnosed when the clinical criteria satisfy one of the established scoring systems.

Patients with DRESS syndrome can have heterogeneous manifestations. As a result, patients may develop a drug hypersensitivity with biological behavior and a natural history compatible with DRESS syndrome that does not fulfill published diagnostic criteria.⁵ The syndrome also may reveal its component manifestations gradually, thus delaying the diagnosis. The terms mini-DRESS and skirt syndrome have been employed to describe drug eruptions that clearly have systemic symptoms and more complex and pernicious biologic behavior than a simple drug exanthema but do not meet DRESS syndrome criteria. Ultimately, it is important to note that in clinical practice, DRESS syndrome exists on a spectrum of severity and the diagnosis remains a clinical one.

Pearl: The most commonly involved organ in DRESS syndrome is the liver.

Liver involvement is the most common visceral organ involved in DRESS syndrome and is estimated to occur in approximately 45.0% to 86.1% of cases.^6,7 If a patient develops the characteristic rash, peripheral blood eosinophilia, and evidence of liver injury, DRESS syndrome must be included in the differential diagnosis.

Hepatitis presenting in DRESS syndrome can be hepatocellular, cholestatic, or mixed.^6,7 Case series are varied in whether the transaminitis of DRESS syndrome tends to be more hepatocellular⁸ or cholestatic.⁷ Liver dysfunction in DRESS syndrome often lasts longer than in other severe cutaneous adverse drug reactions, and patients may improve anywhere from a few days in milder cases to months to achieve resolution of abnormalities.^6,7 Severe hepatic involvement is thought to be the most notable cause of mortality.⁹

Pearl: New-onset proteinuria, hematuria, and sterile pyuria indicate acute interstitial nephritis that may be associated with DRESS syndrome.

Acute interstitial nephritis (AIN) is a drug-induced form of acute kidney injury that can co-occur with DRESS syndrome. Acute interstitial nephritis can present with some combination of acute kidney injury, morbilliform eruption, eosinophilia, fever, and sometimes eosinophiluria. Although AIN can be distinct from DRESS syndrome, there are cases of DRESS syndrome associated with AIN.¹⁰ In the correct clinical context, urinalysis may help by showing new-onset proteinuria, new-onset hematuria, and sterile pyuria. More common causes of acute kidney injury such as prerenal etiologies and acute tubular necrosis have a bland urinary sediment.

Myth: If the eruption is not morbilliform, then it is not DRESS syndrome.

The most common morphology of DRESS syndrome is a morbilliform eruption (Figure 1), but urticarial and atypical targetoid (erythema multiforme–like) eruptions also have been described.⁹ Rarely, DRESS syndrome secondary to use of allopurinol or anticonvulsants may have a pustular morphology (Figure 2), which is distinguished from acute generalized exanthematous pustulosis by its delayed onset, more severe visceral involvement, and prolonged course.¹¹

Another reported variant demonstrates overlapping features between Stevens-Johnson syndrome/toxic epidermal necrolysis and DRESS syndrome. It may present with mucositis, atypical targetoid lesions, and vesiculobullous lesions.¹² It is unclear whether this reported variant is indeed a true subtype of DRESS syndrome, as Stevens-Johnson syndrome/toxic epidermal necrolysis may present with systemic symptoms, lymphadenopathy, hepatic, renal, and pulmonary complications, among other systemic disturbances.¹²

Pearl: Facial edema noted during physical examination is an important clue of DRESS syndrome.

Perhaps the most helpful findings in the diagnosis of DRESS syndrome are facial edema and anasarca (Figure 3), as facial edema is not a usual finding in sepsis. Facial edema can be severe enough that the patient’s features are dramatically altered. It may be useful to ask family members if the patient’s face appears swollen or to compare the current appearance to the patient’s driver’s license photograph. An important complication to note is laryngeal edema, which may complicate airway management and may manifest as respiratory distress, stridor, and the need for emergent intubation.¹³

Myth: Patients who have had an allergic reaction to sulfonamide antibiotics will have a cross-reaction to nonantibiotic sulfonamides.

A common question is, if a patient has had a prior allergy to sulfonamide antibiotics, then are nonantibiotic sulfones such as a sulfonylurea, thiazide diuretic, or furosemide likely to cause a a cross-reaction? In one study (N=969), only 9.9% of patients with a prior sulfone antibiotic allergy developed hypersensitivity when exposed to a nonantibiotic sulfone, which is thought to be due to an overall increased propensity for hypersensitivity rather than a true cross-reaction. In fact, the risk for developing a hypersensitivity reaction to penicillin (14.0% [717/5115]) was higher than the risk for developing a reaction from a nonantibiotic sulfone among these patients.¹⁴ This study bolsters the argument that if there are other potential culprit medications and the time course for a patient’s nonantibiotic sulfone is not consistent with the timeline for DRESS syndrome, it may be beneficial to look for a different causative agent.

Pearl: Vancomycin is an important cause of DRESS syndrome.

Guidelines for treating endocarditis and osteomyelitis caused by methicillin-resistant Staphylococcus aureus infection recommend intravenous vancomycin for 4 to 6 weeks.¹⁵ This duration is within the relevant time frame of exposure for the development of DRESS syndrome de novo.

One case series noted that 37.5% (12/32) of DRESS syndrome cases in a 3-year period were caused by vancomycin, which notably was the most common medication associated with DRESS syndrome.¹⁶ There were caveats to this case series in that no standardized drug causality score was used and the sample size over the 3-year period was small; however, the increased use (and misuse) of antibiotics and perhaps increased recognition of rash in outpatient parenteral antibiotic therapy clinics may play a role if vancomycin-induced DRESS syndrome is indeed becoming more common.

Myth: Myocarditis secondary to DRESS syndrome will present with chest pain at the time of the cutaneous eruption.

Few patients with DRESS syndrome–associated myocarditis actually are symptomatic during their hospitalization.⁴ In asymptomatic patients, the primary team and consultants should be vigilant for the potential of subclinical myocarditis or the possibility of developing cardiac involvement after discharge, as myocarditis secondary to DRESS syndrome may present any time from rash onset up to 4 months later.⁴ Therefore, DRESS patients should be especially attentive to any new cardiac symptoms and notify their provider if any develop.

Although no standard cardiac screening guidelines exist for DRESS syndrome, some have recommended that baseline cardiac screening tests including electrocardiogram, troponin levels, and echocardiogram be considered at the time of diagnosis.⁵ If any testing is abnormal, DRESS syndrome–associated myocarditis should be suspected and an endomyocardial biopsy, which is the diagnostic gold standard, may be necessary.⁴ If the cardiac screening tests are normal, some investigators recommend serial outpatient echocardiograms for all DRESS patients, even those who remain asymptomatic.¹⁷ An alternative is an empiric approach in which a thorough review of systems is performed and testing is done if patients develop symptoms that are concerning for myocarditis.

Pearl: Steroids are not the only treatment used to control DRESS syndrome.

A prolonged taper of systemic steroids is the first-line treatment of DRESS syndrome. Steroids at the equivalent of 1 to 2 mg/kg daily (once or divided into 2 doses) of prednisone typically are used. For severe and/or recalcitrant DRESS syndrome, 2 mg/kg daily (once or divided into 2 doses) typically is used, and less than 1 mg/kg daily may be used for mini-DRESS syndrome.

Clinical improvement of DRESS syndrome has been demonstrated in several case reports with intravenous immunoglobulin, cyclosporine, cyclophosphamide, mycophenolate mofetil, and plasmapheresis.^18-21 Each of these therapies typically were initiated as second-line therapeutic agents when initial treatment with steroids failed. It is important to note that large prospective studies regarding these treatments are lacking; however, there have been case reports of acute necrotizing eosinophilic myocarditis that did not respond to the combination of steroids and cyclosporine.^4,22

Although there have been successful case reports using intravenous immunoglobulin, a 2012 prospective open-label clinical trial reported notable side effects in 5 of 6 (83.3%) patients with only 1 of 6 (16.6%) achieving the primary end point of control of fever/symptoms at day 7 and clinical remission without steroids on day 30.²³

Pearl: DRESS patients need to be monitored for long-term sequelae such as autoimmune disease.

Several autoimmune conditions may develop as a delayed complication of DRESS syndrome, including autoimmune thyroiditis, systemic lupus erythematosus, type 1 diabetes mellitus, and autoimmune hemolytic anemia.^24-26 Incidence rates of autoimmunity following DRESS syndrome range from 3% to 5% among small case series.^24,25

Autoimmune thyroiditis, which may present as Graves disease, Hashimoto thyroiditis, or painless thyroiditis, is the most common autoimmune disorder to develop in DRESS patients and appears from several weeks to up to 3 years after DRESS.²⁴ Therefore, all DRESS patients should be monitored longitudinally for several years for signs or symptoms suggestive of an autoimmune condition.^5,24,26

Because no guidelines exist regarding serial monitoring for autoimmune sequelae, it may be reasonable to check thyroid function tests at the time of diagnosis and regularly for at least 2 years after diagnosis.⁵ Alternatively, clinicians may consider an empiric approach to laboratory testing that is guided by the development of clinical symptoms.

Pearl: Small cases series suggest differences between adult and pediatric DRESS syndrome, but there are no large studies in children.

Small case series have suggested there may be noteworthy differences between DRESS syndrome in adults and children. Although human herpesvirus 6 (HHV-6) positivity in DRESS syndrome in adults may be as high as 80%, 13% of pediatric patients in one cohort tested positive for HHV-6, though the study size was limited at 29 total patients.²⁷ In children, DRESS syndrome secondary to antibiotics was associated with a shorter latency time as compared to cases secondary to nonantibiotics. In contrast to the typical 2- to 6-week timeline, Sasidharanpillai et al²⁸ reported an average onset 5.8 days after drug administration in antibiotic-associated DRESS syndrome compared to 23.9 days for anticonvulsants, though this study only included 11 total patients. Other reports have suggested a similar trend.²⁷

The role of HHV-6 positivity in pediatric DRESS syndrome and its influence on prognosis remains unclear. One study showed a worse prognosis for pediatric patients with positive HHV-6 antibodies.²⁷ However, with such a small sample size—only 4 HHV-6–positive patients of 29 pediatric DRESS cases—larger studies are needed to better characterize the relationship between HHV-6 positivity and prognosis.

Drug rash with eosinophilia and systemic symptoms (DRESS syndrome), also known as drug-induced hypersensitivity syndrome, is an uncommon severe systemic hypersensitivity drug reaction. It is estimated to occur in 1 in every 1000 to 10,000 drug exposures.¹ It can affect patients of all ages and typically presents 2 to 6 weeks after exposure to a culprit medication. Classically, DRESS syndrome presents with often widespread rash, facial edema, systemic symptoms such as fever, lymphadenopathy, and evidence of visceral organ involvement. Peripheral blood eosinophilia is frequently but not universally observed.^1,2

Even with proper management, reported DRESS syndrome mortality rates worldwide are approximately 10%² or higher depending on the degree and type of other organ involvement (eg, cardiac).³ Beyond the acute manifestations of DRESS syndrome, this condition is unique in that some patients develop late-onset sequelae such as myocarditis or autoimmune conditions even years after the initial cutaneous eruption.⁴ Therefore, longitudinal evaluation is a key component of management.

The clinical myths and pearls presented here highlight some of the commonly held assumptions regarding DRESS syndrome in an effort to illuminate subtleties of managing patients with this condition (Table).

Myth: DRESS syndrome may only be diagnosed when the clinical criteria satisfy one of the established scoring systems.

Patients with DRESS syndrome can have heterogeneous manifestations. As a result, patients may develop a drug hypersensitivity with biological behavior and a natural history compatible with DRESS syndrome that does not fulfill published diagnostic criteria.⁵ The syndrome also may reveal its component manifestations gradually, thus delaying the diagnosis. The terms mini-DRESS and skirt syndrome have been employed to describe drug eruptions that clearly have systemic symptoms and more complex and pernicious biologic behavior than a simple drug exanthema but do not meet DRESS syndrome criteria. Ultimately, it is important to note that in clinical practice, DRESS syndrome exists on a spectrum of severity and the diagnosis remains a clinical one.

Pearl: The most commonly involved organ in DRESS syndrome is the liver.

Liver involvement is the most common visceral organ involved in DRESS syndrome and is estimated to occur in approximately 45.0% to 86.1% of cases.^6,7 If a patient develops the characteristic rash, peripheral blood eosinophilia, and evidence of liver injury, DRESS syndrome must be included in the differential diagnosis.

Hepatitis presenting in DRESS syndrome can be hepatocellular, cholestatic, or mixed.^6,7 Case series are varied in whether the transaminitis of DRESS syndrome tends to be more hepatocellular⁸ or cholestatic.⁷ Liver dysfunction in DRESS syndrome often lasts longer than in other severe cutaneous adverse drug reactions, and patients may improve anywhere from a few days in milder cases to months to achieve resolution of abnormalities.^6,7 Severe hepatic involvement is thought to be the most notable cause of mortality.⁹

Pearl: New-onset proteinuria, hematuria, and sterile pyuria indicate acute interstitial nephritis that may be associated with DRESS syndrome.

Acute interstitial nephritis (AIN) is a drug-induced form of acute kidney injury that can co-occur with DRESS syndrome. Acute interstitial nephritis can present with some combination of acute kidney injury, morbilliform eruption, eosinophilia, fever, and sometimes eosinophiluria. Although AIN can be distinct from DRESS syndrome, there are cases of DRESS syndrome associated with AIN.¹⁰ In the correct clinical context, urinalysis may help by showing new-onset proteinuria, new-onset hematuria, and sterile pyuria. More common causes of acute kidney injury such as prerenal etiologies and acute tubular necrosis have a bland urinary sediment.

Myth: If the eruption is not morbilliform, then it is not DRESS syndrome.

The most common morphology of DRESS syndrome is a morbilliform eruption (Figure 1), but urticarial and atypical targetoid (erythema multiforme–like) eruptions also have been described.⁹ Rarely, DRESS syndrome secondary to use of allopurinol or anticonvulsants may have a pustular morphology (Figure 2), which is distinguished from acute generalized exanthematous pustulosis by its delayed onset, more severe visceral involvement, and prolonged course.¹¹

Another reported variant demonstrates overlapping features between Stevens-Johnson syndrome/toxic epidermal necrolysis and DRESS syndrome. It may present with mucositis, atypical targetoid lesions, and vesiculobullous lesions.¹² It is unclear whether this reported variant is indeed a true subtype of DRESS syndrome, as Stevens-Johnson syndrome/toxic epidermal necrolysis may present with systemic symptoms, lymphadenopathy, hepatic, renal, and pulmonary complications, among other systemic disturbances.¹²

Pearl: Facial edema noted during physical examination is an important clue of DRESS syndrome.

Perhaps the most helpful findings in the diagnosis of DRESS syndrome are facial edema and anasarca (Figure 3), as facial edema is not a usual finding in sepsis. Facial edema can be severe enough that the patient’s features are dramatically altered. It may be useful to ask family members if the patient’s face appears swollen or to compare the current appearance to the patient’s driver’s license photograph. An important complication to note is laryngeal edema, which may complicate airway management and may manifest as respiratory distress, stridor, and the need for emergent intubation.¹³

Myth: Patients who have had an allergic reaction to sulfonamide antibiotics will have a cross-reaction to nonantibiotic sulfonamides.

A common question is, if a patient has had a prior allergy to sulfonamide antibiotics, then are nonantibiotic sulfones such as a sulfonylurea, thiazide diuretic, or furosemide likely to cause a a cross-reaction? In one study (N=969), only 9.9% of patients with a prior sulfone antibiotic allergy developed hypersensitivity when exposed to a nonantibiotic sulfone, which is thought to be due to an overall increased propensity for hypersensitivity rather than a true cross-reaction. In fact, the risk for developing a hypersensitivity reaction to penicillin (14.0% [717/5115]) was higher than the risk for developing a reaction from a nonantibiotic sulfone among these patients.¹⁴ This study bolsters the argument that if there are other potential culprit medications and the time course for a patient’s nonantibiotic sulfone is not consistent with the timeline for DRESS syndrome, it may be beneficial to look for a different causative agent.

Pearl: Vancomycin is an important cause of DRESS syndrome.

Guidelines for treating endocarditis and osteomyelitis caused by methicillin-resistant Staphylococcus aureus infection recommend intravenous vancomycin for 4 to 6 weeks.¹⁵ This duration is within the relevant time frame of exposure for the development of DRESS syndrome de novo.

One case series noted that 37.5% (12/32) of DRESS syndrome cases in a 3-year period were caused by vancomycin, which notably was the most common medication associated with DRESS syndrome.¹⁶ There were caveats to this case series in that no standardized drug causality score was used and the sample size over the 3-year period was small; however, the increased use (and misuse) of antibiotics and perhaps increased recognition of rash in outpatient parenteral antibiotic therapy clinics may play a role if vancomycin-induced DRESS syndrome is indeed becoming more common.

Myth: Myocarditis secondary to DRESS syndrome will present with chest pain at the time of the cutaneous eruption.

Few patients with DRESS syndrome–associated myocarditis actually are symptomatic during their hospitalization.⁴ In asymptomatic patients, the primary team and consultants should be vigilant for the potential of subclinical myocarditis or the possibility of developing cardiac involvement after discharge, as myocarditis secondary to DRESS syndrome may present any time from rash onset up to 4 months later.⁴ Therefore, DRESS patients should be especially attentive to any new cardiac symptoms and notify their provider if any develop.

Although no standard cardiac screening guidelines exist for DRESS syndrome, some have recommended that baseline cardiac screening tests including electrocardiogram, troponin levels, and echocardiogram be considered at the time of diagnosis.⁵ If any testing is abnormal, DRESS syndrome–associated myocarditis should be suspected and an endomyocardial biopsy, which is the diagnostic gold standard, may be necessary.⁴ If the cardiac screening tests are normal, some investigators recommend serial outpatient echocardiograms for all DRESS patients, even those who remain asymptomatic.¹⁷ An alternative is an empiric approach in which a thorough review of systems is performed and testing is done if patients develop symptoms that are concerning for myocarditis.

Pearl: Steroids are not the only treatment used to control DRESS syndrome.

A prolonged taper of systemic steroids is the first-line treatment of DRESS syndrome. Steroids at the equivalent of 1 to 2 mg/kg daily (once or divided into 2 doses) of prednisone typically are used. For severe and/or recalcitrant DRESS syndrome, 2 mg/kg daily (once or divided into 2 doses) typically is used, and less than 1 mg/kg daily may be used for mini-DRESS syndrome.

Clinical improvement of DRESS syndrome has been demonstrated in several case reports with intravenous immunoglobulin, cyclosporine, cyclophosphamide, mycophenolate mofetil, and plasmapheresis.^18-21 Each of these therapies typically were initiated as second-line therapeutic agents when initial treatment with steroids failed. It is important to note that large prospective studies regarding these treatments are lacking; however, there have been case reports of acute necrotizing eosinophilic myocarditis that did not respond to the combination of steroids and cyclosporine.^4,22

Although there have been successful case reports using intravenous immunoglobulin, a 2012 prospective open-label clinical trial reported notable side effects in 5 of 6 (83.3%) patients with only 1 of 6 (16.6%) achieving the primary end point of control of fever/symptoms at day 7 and clinical remission without steroids on day 30.²³

Pearl: DRESS patients need to be monitored for long-term sequelae such as autoimmune disease.

Several autoimmune conditions may develop as a delayed complication of DRESS syndrome, including autoimmune thyroiditis, systemic lupus erythematosus, type 1 diabetes mellitus, and autoimmune hemolytic anemia.^24-26 Incidence rates of autoimmunity following DRESS syndrome range from 3% to 5% among small case series.^24,25

Autoimmune thyroiditis, which may present as Graves disease, Hashimoto thyroiditis, or painless thyroiditis, is the most common autoimmune disorder to develop in DRESS patients and appears from several weeks to up to 3 years after DRESS.²⁴ Therefore, all DRESS patients should be monitored longitudinally for several years for signs or symptoms suggestive of an autoimmune condition.^5,24,26

Because no guidelines exist regarding serial monitoring for autoimmune sequelae, it may be reasonable to check thyroid function tests at the time of diagnosis and regularly for at least 2 years after diagnosis.⁵ Alternatively, clinicians may consider an empiric approach to laboratory testing that is guided by the development of clinical symptoms.

Pearl: Small cases series suggest differences between adult and pediatric DRESS syndrome, but there are no large studies in children.

Small case series have suggested there may be noteworthy differences between DRESS syndrome in adults and children. Although human herpesvirus 6 (HHV-6) positivity in DRESS syndrome in adults may be as high as 80%, 13% of pediatric patients in one cohort tested positive for HHV-6, though the study size was limited at 29 total patients.²⁷ In children, DRESS syndrome secondary to antibiotics was associated with a shorter latency time as compared to cases secondary to nonantibiotics. In contrast to the typical 2- to 6-week timeline, Sasidharanpillai et al²⁸ reported an average onset 5.8 days after drug administration in antibiotic-associated DRESS syndrome compared to 23.9 days for anticonvulsants, though this study only included 11 total patients. Other reports have suggested a similar trend.²⁷

The role of HHV-6 positivity in pediatric DRESS syndrome and its influence on prognosis remains unclear. One study showed a worse prognosis for pediatric patients with positive HHV-6 antibodies.²⁷ However, with such a small sample size—only 4 HHV-6–positive patients of 29 pediatric DRESS cases—larger studies are needed to better characterize the relationship between HHV-6 positivity and prognosis.

The Diagnosis: Cutaneous Macroglobulinosis

Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma that produces a circulating monoclonal IgM. Incidence in the United States is 1500 patients annually, most commonly men in their 70s.¹ The disease process is largely indolent, with early symptoms consisting of generalized weakness, weight loss, and fatigue. Signs of lymphadenopathy, hepatosplenomegaly, and cytopenia may emerge as the disease progresses. Diagnostic criteria include bone marrow biopsy with plasmacytoid/plasmacellular infiltrate; IgM monoclonal gammopathy; and end-organ damage, which may include cutaneous manifestations.²

Cutaneous findings in Waldenström macroglobulinemia are nonspecific and secondary to the disease's hematologic manifestations, presenting as livedo reticularis, purpura, and mucosal bleeding.³ True cutaneous involvement of the disease is rare and was first described in 1978 by Tichenor.⁴ Specific cutaneous lesions have 2 separate clinical presentations: (1) a primary cutaneous infiltrate of lymphoplasmacytic cells, and (2) deposition of IgM in the dermis.⁵ Although the primary infiltrate of neoplastic cells appears as erythematous firm papules or plaques on the face and trunk, similar to other manifestations of leukemia cutis, deposition of IgM presents as translucent papules and plaques and is located more distally, particularly on the extensor extremities.6 These depositional plaques are not pruritic but may be tender if located over sites of pressure, as seen with the plantar presentation in our patient.

Histologically, cutaneous macroglobulinosis demonstrates IgM deposition in perieccrine, perivascular, or intravascular tissue that is periodic acid-Schiff (PAS) positive.⁷ Staining with Congo red and Alcian blue is negative. In our case, biopsy showed a nodular deposition of hypocellular globular material that stained brightly with PAS and PAS diastase. With Masson trichome stain, intensity of staining diminished, suggesting that the deposition was not composed of collagen; rather, this deposition appeared to consist of IgM storage papules on immunohistochemistry (Figure 1). Further workup revealed borderline pancytopenia and elevated globulins with a monoclonal peak on serum protein electrophoresis, confirming the diagnosis of cutaneous macroglobulinosis secondary to Waldenström macroglobulinemia.

A PubMed search of articles indexed for MEDLINE using the terms cutaneous, macroglobulinosis, macroglobulinemia, Waldenström's macroglobulinemia, Waldenström's macroglobulinaemia, and macroglobulinemia cutis revealed a total of 19 cases of cutaneous macroglobulinosis (including this case). The average age of presentation in these cases is 60 years (range, 29-83 years) with a predisposition for men (68% [13/19]). The development of cutaneous macroglobulinosis primarily has been noted following diagnosis of Waldenström macroglobulinemia (53% [10/19]), with some cases prior to diagnosis (37% [7/19]) or at the time of diagnosis (11% [2/19]). The presence of cutaneous lesions does not correlate with prognosis of the underlying malignancy.^5,8,9

Systemic treatment of the underlying macroglobulinemia has been suggested for symptomatic cases of cutaneous macroglobulinosis.³ Prior therapy has consisted primarily of chlorambucil; however, treatment with rituximab, occasionally in conjunction with the proteasome inhibitor bortezomib, recently has been reported.¹⁰ Because of the symptomatic nature of our patient's lesions, she was referred to the oncology department and started on rituximab therapy. The lesions improved with therapy and have remained stable following treatment.

The differential diagnosis for tender pink papules and plaques on the arms and legs includes tophaceous gout, plantar fibromatosis, erythropoietic protoporphyria, and acral fibrokeratoma.

Gouty tophi commonly accumulate as painful, edematous, yellow to whitish nodules and tumors with erythema, often overlying joints or extensor surfaces. Histopathologic examination after formalin fixation shows needle-shaped clefts within feathery amorphous pink areas surrounded by granuloma (Figure 2).¹¹ Yellow, needle-shaped, negatively birefringent crystals can be viewed under polarized microscopy in alcohol-fixed samples.

Plantar fibromatosis (Ledderhose disease) is a benign proliferation of the plantar aponeurosis linked to alcohol use; liver disease; and notably epilepsy,¹² a component of our patient's medical history. Large nodules appear grossly on the plantar feet and may progress to contractures in more advanced lesions. Biopsy reveals bland hyperproliferation of fibroblasts in a background of fascial fibrous tissue (Figure 3).¹² Clinically, this diagnosis is part of the differential diagnosis of plantar nodules but appears histologically different than cutaneous macroglobulinosis because there are no hyaline deposits in plantar fibromatosis.

Erythropoietic protoporphyria is a rare disorder that primarily arises due to a congenital deficiency in the ferrochelatase enzyme involved in heme biosynthesis. Erythropoietic protoporphyria is the most common porphyria among children and typically presents in infancy or early childhood as a painful photosensitivity with ensuing cutaneous manifestations and possible hepatobiliary disease. Edema and severe burning pain can be noted within minutes of sun exposure in a dose-response relationship.13 Histologic findings of erythropoietic protoporphyria differ based on acute or chronic skin changes. Acute lesions exhibit a predominantly neutrophilic interstitial dermal infiltrate with vacuoles and intercellular edema. Chronic changes include the accumulation of a PAS-positive, amorphous, hyalinelike substance, similar to the microscopic findings of cutaneous macroglobulinosis (Figure 4).¹³

An acral fibrokeratoma is a benign fibroepithelial tumor that clinically appears as a flesh-colored or slightly erythematous exophytic nodule that most commonly is found on the fingers or toes. Thought to arise from trauma to the affected area, it is histologically characterized by interwoven collagenous bundles with overlying epidermal hyperkeratosis, acanthosis, and deep thickened rete ridges¹⁴ (Figure 5). Although multiple acral fibrokeratomas have been reported (similar to presentations of prurigo nodularis),15 they more commonly appear as solitary lesions as opposed to the numerous translucent papules seen in our patient.

The Diagnosis: Cutaneous Macroglobulinosis

Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma that produces a circulating monoclonal IgM. Incidence in the United States is 1500 patients annually, most commonly men in their 70s.¹ The disease process is largely indolent, with early symptoms consisting of generalized weakness, weight loss, and fatigue. Signs of lymphadenopathy, hepatosplenomegaly, and cytopenia may emerge as the disease progresses. Diagnostic criteria include bone marrow biopsy with plasmacytoid/plasmacellular infiltrate; IgM monoclonal gammopathy; and end-organ damage, which may include cutaneous manifestations.²

Cutaneous findings in Waldenström macroglobulinemia are nonspecific and secondary to the disease's hematologic manifestations, presenting as livedo reticularis, purpura, and mucosal bleeding.³ True cutaneous involvement of the disease is rare and was first described in 1978 by Tichenor.⁴ Specific cutaneous lesions have 2 separate clinical presentations: (1) a primary cutaneous infiltrate of lymphoplasmacytic cells, and (2) deposition of IgM in the dermis.⁵ Although the primary infiltrate of neoplastic cells appears as erythematous firm papules or plaques on the face and trunk, similar to other manifestations of leukemia cutis, deposition of IgM presents as translucent papules and plaques and is located more distally, particularly on the extensor extremities.6 These depositional plaques are not pruritic but may be tender if located over sites of pressure, as seen with the plantar presentation in our patient.

Histologically, cutaneous macroglobulinosis demonstrates IgM deposition in perieccrine, perivascular, or intravascular tissue that is periodic acid-Schiff (PAS) positive.⁷ Staining with Congo red and Alcian blue is negative. In our case, biopsy showed a nodular deposition of hypocellular globular material that stained brightly with PAS and PAS diastase. With Masson trichome stain, intensity of staining diminished, suggesting that the deposition was not composed of collagen; rather, this deposition appeared to consist of IgM storage papules on immunohistochemistry (Figure 1). Further workup revealed borderline pancytopenia and elevated globulins with a monoclonal peak on serum protein electrophoresis, confirming the diagnosis of cutaneous macroglobulinosis secondary to Waldenström macroglobulinemia.

A PubMed search of articles indexed for MEDLINE using the terms cutaneous, macroglobulinosis, macroglobulinemia, Waldenström's macroglobulinemia, Waldenström's macroglobulinaemia, and macroglobulinemia cutis revealed a total of 19 cases of cutaneous macroglobulinosis (including this case). The average age of presentation in these cases is 60 years (range, 29-83 years) with a predisposition for men (68% [13/19]). The development of cutaneous macroglobulinosis primarily has been noted following diagnosis of Waldenström macroglobulinemia (53% [10/19]), with some cases prior to diagnosis (37% [7/19]) or at the time of diagnosis (11% [2/19]). The presence of cutaneous lesions does not correlate with prognosis of the underlying malignancy.^5,8,9

Systemic treatment of the underlying macroglobulinemia has been suggested for symptomatic cases of cutaneous macroglobulinosis.³ Prior therapy has consisted primarily of chlorambucil; however, treatment with rituximab, occasionally in conjunction with the proteasome inhibitor bortezomib, recently has been reported.¹⁰ Because of the symptomatic nature of our patient's lesions, she was referred to the oncology department and started on rituximab therapy. The lesions improved with therapy and have remained stable following treatment.

The differential diagnosis for tender pink papules and plaques on the arms and legs includes tophaceous gout, plantar fibromatosis, erythropoietic protoporphyria, and acral fibrokeratoma.

Gouty tophi commonly accumulate as painful, edematous, yellow to whitish nodules and tumors with erythema, often overlying joints or extensor surfaces. Histopathologic examination after formalin fixation shows needle-shaped clefts within feathery amorphous pink areas surrounded by granuloma (Figure 2).¹¹ Yellow, needle-shaped, negatively birefringent crystals can be viewed under polarized microscopy in alcohol-fixed samples.

Plantar fibromatosis (Ledderhose disease) is a benign proliferation of the plantar aponeurosis linked to alcohol use; liver disease; and notably epilepsy,¹² a component of our patient's medical history. Large nodules appear grossly on the plantar feet and may progress to contractures in more advanced lesions. Biopsy reveals bland hyperproliferation of fibroblasts in a background of fascial fibrous tissue (Figure 3).¹² Clinically, this diagnosis is part of the differential diagnosis of plantar nodules but appears histologically different than cutaneous macroglobulinosis because there are no hyaline deposits in plantar fibromatosis.

Erythropoietic protoporphyria is a rare disorder that primarily arises due to a congenital deficiency in the ferrochelatase enzyme involved in heme biosynthesis. Erythropoietic protoporphyria is the most common porphyria among children and typically presents in infancy or early childhood as a painful photosensitivity with ensuing cutaneous manifestations and possible hepatobiliary disease. Edema and severe burning pain can be noted within minutes of sun exposure in a dose-response relationship.13 Histologic findings of erythropoietic protoporphyria differ based on acute or chronic skin changes. Acute lesions exhibit a predominantly neutrophilic interstitial dermal infiltrate with vacuoles and intercellular edema. Chronic changes include the accumulation of a PAS-positive, amorphous, hyalinelike substance, similar to the microscopic findings of cutaneous macroglobulinosis (Figure 4).¹³

An acral fibrokeratoma is a benign fibroepithelial tumor that clinically appears as a flesh-colored or slightly erythematous exophytic nodule that most commonly is found on the fingers or toes. Thought to arise from trauma to the affected area, it is histologically characterized by interwoven collagenous bundles with overlying epidermal hyperkeratosis, acanthosis, and deep thickened rete ridges¹⁴ (Figure 5). Although multiple acral fibrokeratomas have been reported (similar to presentations of prurigo nodularis),15 they more commonly appear as solitary lesions as opposed to the numerous translucent papules seen in our patient.

The Diagnosis: Cutaneous Macroglobulinosis

Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma that produces a circulating monoclonal IgM. Incidence in the United States is 1500 patients annually, most commonly men in their 70s.¹ The disease process is largely indolent, with early symptoms consisting of generalized weakness, weight loss, and fatigue. Signs of lymphadenopathy, hepatosplenomegaly, and cytopenia may emerge as the disease progresses. Diagnostic criteria include bone marrow biopsy with plasmacytoid/plasmacellular infiltrate; IgM monoclonal gammopathy; and end-organ damage, which may include cutaneous manifestations.²

Cutaneous findings in Waldenström macroglobulinemia are nonspecific and secondary to the disease's hematologic manifestations, presenting as livedo reticularis, purpura, and mucosal bleeding.³ True cutaneous involvement of the disease is rare and was first described in 1978 by Tichenor.⁴ Specific cutaneous lesions have 2 separate clinical presentations: (1) a primary cutaneous infiltrate of lymphoplasmacytic cells, and (2) deposition of IgM in the dermis.⁵ Although the primary infiltrate of neoplastic cells appears as erythematous firm papules or plaques on the face and trunk, similar to other manifestations of leukemia cutis, deposition of IgM presents as translucent papules and plaques and is located more distally, particularly on the extensor extremities.6 These depositional plaques are not pruritic but may be tender if located over sites of pressure, as seen with the plantar presentation in our patient.

Histologically, cutaneous macroglobulinosis demonstrates IgM deposition in perieccrine, perivascular, or intravascular tissue that is periodic acid-Schiff (PAS) positive.⁷ Staining with Congo red and Alcian blue is negative. In our case, biopsy showed a nodular deposition of hypocellular globular material that stained brightly with PAS and PAS diastase. With Masson trichome stain, intensity of staining diminished, suggesting that the deposition was not composed of collagen; rather, this deposition appeared to consist of IgM storage papules on immunohistochemistry (Figure 1). Further workup revealed borderline pancytopenia and elevated globulins with a monoclonal peak on serum protein electrophoresis, confirming the diagnosis of cutaneous macroglobulinosis secondary to Waldenström macroglobulinemia.

A PubMed search of articles indexed for MEDLINE using the terms cutaneous, macroglobulinosis, macroglobulinemia, Waldenström's macroglobulinemia, Waldenström's macroglobulinaemia, and macroglobulinemia cutis revealed a total of 19 cases of cutaneous macroglobulinosis (including this case). The average age of presentation in these cases is 60 years (range, 29-83 years) with a predisposition for men (68% [13/19]). The development of cutaneous macroglobulinosis primarily has been noted following diagnosis of Waldenström macroglobulinemia (53% [10/19]), with some cases prior to diagnosis (37% [7/19]) or at the time of diagnosis (11% [2/19]). The presence of cutaneous lesions does not correlate with prognosis of the underlying malignancy.^5,8,9

Systemic treatment of the underlying macroglobulinemia has been suggested for symptomatic cases of cutaneous macroglobulinosis.³ Prior therapy has consisted primarily of chlorambucil; however, treatment with rituximab, occasionally in conjunction with the proteasome inhibitor bortezomib, recently has been reported.¹⁰ Because of the symptomatic nature of our patient's lesions, she was referred to the oncology department and started on rituximab therapy. The lesions improved with therapy and have remained stable following treatment.

The differential diagnosis for tender pink papules and plaques on the arms and legs includes tophaceous gout, plantar fibromatosis, erythropoietic protoporphyria, and acral fibrokeratoma.

Gouty tophi commonly accumulate as painful, edematous, yellow to whitish nodules and tumors with erythema, often overlying joints or extensor surfaces. Histopathologic examination after formalin fixation shows needle-shaped clefts within feathery amorphous pink areas surrounded by granuloma (Figure 2).¹¹ Yellow, needle-shaped, negatively birefringent crystals can be viewed under polarized microscopy in alcohol-fixed samples.

Plantar fibromatosis (Ledderhose disease) is a benign proliferation of the plantar aponeurosis linked to alcohol use; liver disease; and notably epilepsy,¹² a component of our patient's medical history. Large nodules appear grossly on the plantar feet and may progress to contractures in more advanced lesions. Biopsy reveals bland hyperproliferation of fibroblasts in a background of fascial fibrous tissue (Figure 3).¹² Clinically, this diagnosis is part of the differential diagnosis of plantar nodules but appears histologically different than cutaneous macroglobulinosis because there are no hyaline deposits in plantar fibromatosis.

Erythropoietic protoporphyria is a rare disorder that primarily arises due to a congenital deficiency in the ferrochelatase enzyme involved in heme biosynthesis. Erythropoietic protoporphyria is the most common porphyria among children and typically presents in infancy or early childhood as a painful photosensitivity with ensuing cutaneous manifestations and possible hepatobiliary disease. Edema and severe burning pain can be noted within minutes of sun exposure in a dose-response relationship.13 Histologic findings of erythropoietic protoporphyria differ based on acute or chronic skin changes. Acute lesions exhibit a predominantly neutrophilic interstitial dermal infiltrate with vacuoles and intercellular edema. Chronic changes include the accumulation of a PAS-positive, amorphous, hyalinelike substance, similar to the microscopic findings of cutaneous macroglobulinosis (Figure 4).¹³

An acral fibrokeratoma is a benign fibroepithelial tumor that clinically appears as a flesh-colored or slightly erythematous exophytic nodule that most commonly is found on the fingers or toes. Thought to arise from trauma to the affected area, it is histologically characterized by interwoven collagenous bundles with overlying epidermal hyperkeratosis, acanthosis, and deep thickened rete ridges¹⁴ (Figure 5). Although multiple acral fibrokeratomas have been reported (similar to presentations of prurigo nodularis),15 they more commonly appear as solitary lesions as opposed to the numerous translucent papules seen in our patient.

The Society for Pediatric Dermatology (SPD) was established in 1975, and the pediatric dermatology workforce shortage began shortly after. In 1986, Honig and Burke¹ reported that opportunities in pediatric dermatology were limited and that pediatric dermatologists were predominantly located in larger teaching hospitals and selected private practice settings; furthermore, only approximately 20% had patient populations comprising more than 75% children.¹ Positive changes have occurred since that time, with more practitioners dedicated to pediatric dermatology and increased opportunities within the specialty. The SPD has expanded to a thriving group of collegial pediatric dermatologists now topping 1200 members worldwide.

Although the SPD has strongly influenced practice development in pediatric dermatology, there are fewer than 300 board-certified pediatric dermatologists in the United States and approximately double that number of pediatric dermatology practitioners. The deficiency is glaring based on the national population alone. The US Census Bureau reported 325,719,178 individuals living in the United States (as of July 1, 2017).² With approximately 75 million children in the United States and estimates that 22.8% of the population is younger than 18 years,³ there currently is 1 pediatric dermatologist for every 120,000 children or more.

As if the numbers alone were not adequate, a number of publications have addressed the benefits of pediatric dermatologists in both dermatology and pediatrics training and furthermore in pediatric care. A 2004 survey of dermatology program directors and chairpersons regarding the issue of the pediatric dermatology workforce shortage revealed that 45 of 94 (47.9%) programs employed a pediatric dermatologist and 24 (25.5%) had been looking to hire one for more than a year.⁴ Although more pediatric dermatologists have joined the workforce, it is not surprising that programs with no pediatric dermatologists want them. First, pediatric dermatologists dramatically improve the quality of training with regard to pediatric dermatology education and can increase dermatology residents’ comfort level with children. In a survey of a group of graduating third-year dermatology residents, dermatology residency program directors, and pediatric dermatology fellowship program directors by Nijhawan et al,⁵ residents who were trained in a program with one or more full-time pediatric dermatologists were more likely to feel competent treating children and to feel satisfied with their training program’s pediatric dermatology curriculum than residents without contact with a full-time pediatric dermatologist (50.0% vs 5.9% [P=.002] and 85.3% vs 52.9% [P<.001], respectively). The availability of a pediatric dermatology fellowship further enhanced satisfaction. Residents in programs with no full-time pediatric dermatologist on staff were more likely to be somewhat or extremely dissatisfied with their pediatric dermatology training. Residency program directors were more satisfied with their curriculums when there was one or more pediatric dermatologist on staff (P<.01).⁵

Programs with pediatric dermatologists also offer easy access to a mentor in the field. In a 2010 survey of pediatric dermatologists (published in 2014), Admani et al⁶ reported that 84% (91/109) of respondents (board-certified pediatric dermatologists) cited mentorship as the most important factor influencing their career choice. Exposure to the specialty was noted as a key motivating factor. In my opinion, the actual inclusion of a pediatric dermatology fellowship, whether the position is filled or not, appears to increase the chances of expansion and retention in the field. In the 2014 SPD workforce survey, more than 62% (61/98) of respondents were fellowship trained.⁷ In 2004 there were only 6 pediatric dermatology fellowship training programs. We have come quite far now with 36 fellowships as of August 12, 2018.⁸ The cost of education of course is not simple when pediatric dermatology fellowships are unfunded by the Accreditation Council for Graduate Medical Education; however, it is clear that the initial investment can create ongoing returns in pediatric dermatology.

Furthermore, due to the outpatient burden of skin disease in a pediatrics practice, providing pediatric trainees with contact with a pediatric dermatologist is needed. Prindaville et al⁹ performed a review from 2006 through 2010 of the National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey databases, which revealed that 9% of 23 million pediatric visits during this time period were for dermatologic diseases; therefore, knowledge of pediatric dermatology is vital to pediatrician training.

As if there was not enough evidence that pediatric dermatologists are in high demand, SPD pediatric dermatology workforce surveys from the last 5 years, which will soon be updated, show similar indications.^7,10 Fogel and Teng¹¹ showed that 60% of surveyed pediatric dermatologists (N=226) were academic and 81% were salaried. Unlike previous data,¹ the investigators showed that children constituted 79.5% of respondents’ patient populations. The academic practice environment favored by the majority of pediatric dermatologists was associated with seeing fewer patients per week and longer wait times (approximately 60 days for a pediatric dermatologist vs 15 days in other practice environments).¹¹ Therefore, the demand continues to be unmet even in many institutions with pediatric dermatology practitioners in place.

For the medical student or resident seeking a career in pediatric dermatology, it appears that finding and working on projects with mentors likely is the key to stepping in the field. From my own experience, pediatric dermatologists are extremely friendly and open to supporting career development in earnest students. Reach out to potential mentors months before starting desired electives, as you are competing with other students and pediatrics, dermatology, and emergency medicine residents. Joining and attending meetings of the SPD is a great way to find direction in this friendly and collegial field. Additionally, pediatric dermatology sessions at the annual meetings of the American Academy of Dermatology are a wonderful way to experience the excitement of the field. As a pediatric dermatologist in practice for almost 2 decades, I can honestly say that the field is always intellectually stimulating and evolving rapidly through enhanced understanding of disease pathogenesis, genetics, and therapeutics. Helping children and their parents/guardians never gets boring.

The solution to improving the size and accessibility of the pediatric dermatology workforce is not simple and likely starts from the bottom up. More than 75% of pediatric dermatologists favor implementing systems to encourage medical students to pursue a career in pediatric dermatology.⁷ Increasing resident exposure to dedicated pediatric dermatology training time enhances satisfaction.⁵ Increased funding of fellowships can help these students and residents meet their goals. Current fellowship training programs now total 36, but not all approved institutions have been able to support a postgraduate year 5 (PGY-5) or higher fellow, and in my experience some institutions have avoided adding a fellow due to lack of funding internally. The average pediatric dermatologist earns $100,000 less than colleagues who treat adults, which is an impediment to the expansion of the field.¹⁰ This disparity may chase away practitioners, especially those with medical school debt. Debt forgiveness programs, enhanced practice development, and better base pay for pediatric dermatologists could positively impact growth in this specialty. Dermatology and pediatrics training programs need to dedicate more money and developmental support for pediatric dermatologists as a way to invest in the quality of pediatric dermatology education for their trainees. By recognizing the true value of the academic contributions of pediatric dermatologists, dermatology residency programs can invest in producing trainees with greater aplomb and acumen in pediatric dermatology.

The Society for Pediatric Dermatology (SPD) was established in 1975, and the pediatric dermatology workforce shortage began shortly after. In 1986, Honig and Burke¹ reported that opportunities in pediatric dermatology were limited and that pediatric dermatologists were predominantly located in larger teaching hospitals and selected private practice settings; furthermore, only approximately 20% had patient populations comprising more than 75% children.¹ Positive changes have occurred since that time, with more practitioners dedicated to pediatric dermatology and increased opportunities within the specialty. The SPD has expanded to a thriving group of collegial pediatric dermatologists now topping 1200 members worldwide.

Although the SPD has strongly influenced practice development in pediatric dermatology, there are fewer than 300 board-certified pediatric dermatologists in the United States and approximately double that number of pediatric dermatology practitioners. The deficiency is glaring based on the national population alone. The US Census Bureau reported 325,719,178 individuals living in the United States (as of July 1, 2017).² With approximately 75 million children in the United States and estimates that 22.8% of the population is younger than 18 years,³ there currently is 1 pediatric dermatologist for every 120,000 children or more.

As if the numbers alone were not adequate, a number of publications have addressed the benefits of pediatric dermatologists in both dermatology and pediatrics training and furthermore in pediatric care. A 2004 survey of dermatology program directors and chairpersons regarding the issue of the pediatric dermatology workforce shortage revealed that 45 of 94 (47.9%) programs employed a pediatric dermatologist and 24 (25.5%) had been looking to hire one for more than a year.⁴ Although more pediatric dermatologists have joined the workforce, it is not surprising that programs with no pediatric dermatologists want them. First, pediatric dermatologists dramatically improve the quality of training with regard to pediatric dermatology education and can increase dermatology residents’ comfort level with children. In a survey of a group of graduating third-year dermatology residents, dermatology residency program directors, and pediatric dermatology fellowship program directors by Nijhawan et al,⁵ residents who were trained in a program with one or more full-time pediatric dermatologists were more likely to feel competent treating children and to feel satisfied with their training program’s pediatric dermatology curriculum than residents without contact with a full-time pediatric dermatologist (50.0% vs 5.9% [P=.002] and 85.3% vs 52.9% [P<.001], respectively). The availability of a pediatric dermatology fellowship further enhanced satisfaction. Residents in programs with no full-time pediatric dermatologist on staff were more likely to be somewhat or extremely dissatisfied with their pediatric dermatology training. Residency program directors were more satisfied with their curriculums when there was one or more pediatric dermatologist on staff (P<.01).⁵

Programs with pediatric dermatologists also offer easy access to a mentor in the field. In a 2010 survey of pediatric dermatologists (published in 2014), Admani et al⁶ reported that 84% (91/109) of respondents (board-certified pediatric dermatologists) cited mentorship as the most important factor influencing their career choice. Exposure to the specialty was noted as a key motivating factor. In my opinion, the actual inclusion of a pediatric dermatology fellowship, whether the position is filled or not, appears to increase the chances of expansion and retention in the field. In the 2014 SPD workforce survey, more than 62% (61/98) of respondents were fellowship trained.⁷ In 2004 there were only 6 pediatric dermatology fellowship training programs. We have come quite far now with 36 fellowships as of August 12, 2018.⁸ The cost of education of course is not simple when pediatric dermatology fellowships are unfunded by the Accreditation Council for Graduate Medical Education; however, it is clear that the initial investment can create ongoing returns in pediatric dermatology.

Furthermore, due to the outpatient burden of skin disease in a pediatrics practice, providing pediatric trainees with contact with a pediatric dermatologist is needed. Prindaville et al⁹ performed a review from 2006 through 2010 of the National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey databases, which revealed that 9% of 23 million pediatric visits during this time period were for dermatologic diseases; therefore, knowledge of pediatric dermatology is vital to pediatrician training.

As if there was not enough evidence that pediatric dermatologists are in high demand, SPD pediatric dermatology workforce surveys from the last 5 years, which will soon be updated, show similar indications.^7,10 Fogel and Teng¹¹ showed that 60% of surveyed pediatric dermatologists (N=226) were academic and 81% were salaried. Unlike previous data,¹ the investigators showed that children constituted 79.5% of respondents’ patient populations. The academic practice environment favored by the majority of pediatric dermatologists was associated with seeing fewer patients per week and longer wait times (approximately 60 days for a pediatric dermatologist vs 15 days in other practice environments).¹¹ Therefore, the demand continues to be unmet even in many institutions with pediatric dermatology practitioners in place.

For the medical student or resident seeking a career in pediatric dermatology, it appears that finding and working on projects with mentors likely is the key to stepping in the field. From my own experience, pediatric dermatologists are extremely friendly and open to supporting career development in earnest students. Reach out to potential mentors months before starting desired electives, as you are competing with other students and pediatrics, dermatology, and emergency medicine residents. Joining and attending meetings of the SPD is a great way to find direction in this friendly and collegial field. Additionally, pediatric dermatology sessions at the annual meetings of the American Academy of Dermatology are a wonderful way to experience the excitement of the field. As a pediatric dermatologist in practice for almost 2 decades, I can honestly say that the field is always intellectually stimulating and evolving rapidly through enhanced understanding of disease pathogenesis, genetics, and therapeutics. Helping children and their parents/guardians never gets boring.

The solution to improving the size and accessibility of the pediatric dermatology workforce is not simple and likely starts from the bottom up. More than 75% of pediatric dermatologists favor implementing systems to encourage medical students to pursue a career in pediatric dermatology.⁷ Increasing resident exposure to dedicated pediatric dermatology training time enhances satisfaction.⁵ Increased funding of fellowships can help these students and residents meet their goals. Current fellowship training programs now total 36, but not all approved institutions have been able to support a postgraduate year 5 (PGY-5) or higher fellow, and in my experience some institutions have avoided adding a fellow due to lack of funding internally. The average pediatric dermatologist earns $100,000 less than colleagues who treat adults, which is an impediment to the expansion of the field.¹⁰ This disparity may chase away practitioners, especially those with medical school debt. Debt forgiveness programs, enhanced practice development, and better base pay for pediatric dermatologists could positively impact growth in this specialty. Dermatology and pediatrics training programs need to dedicate more money and developmental support for pediatric dermatologists as a way to invest in the quality of pediatric dermatology education for their trainees. By recognizing the true value of the academic contributions of pediatric dermatologists, dermatology residency programs can invest in producing trainees with greater aplomb and acumen in pediatric dermatology.

The Society for Pediatric Dermatology (SPD) was established in 1975, and the pediatric dermatology workforce shortage began shortly after. In 1986, Honig and Burke¹ reported that opportunities in pediatric dermatology were limited and that pediatric dermatologists were predominantly located in larger teaching hospitals and selected private practice settings; furthermore, only approximately 20% had patient populations comprising more than 75% children.¹ Positive changes have occurred since that time, with more practitioners dedicated to pediatric dermatology and increased opportunities within the specialty. The SPD has expanded to a thriving group of collegial pediatric dermatologists now topping 1200 members worldwide.

Although the SPD has strongly influenced practice development in pediatric dermatology, there are fewer than 300 board-certified pediatric dermatologists in the United States and approximately double that number of pediatric dermatology practitioners. The deficiency is glaring based on the national population alone. The US Census Bureau reported 325,719,178 individuals living in the United States (as of July 1, 2017).² With approximately 75 million children in the United States and estimates that 22.8% of the population is younger than 18 years,³ there currently is 1 pediatric dermatologist for every 120,000 children or more.

As if the numbers alone were not adequate, a number of publications have addressed the benefits of pediatric dermatologists in both dermatology and pediatrics training and furthermore in pediatric care. A 2004 survey of dermatology program directors and chairpersons regarding the issue of the pediatric dermatology workforce shortage revealed that 45 of 94 (47.9%) programs employed a pediatric dermatologist and 24 (25.5%) had been looking to hire one for more than a year.⁴ Although more pediatric dermatologists have joined the workforce, it is not surprising that programs with no pediatric dermatologists want them. First, pediatric dermatologists dramatically improve the quality of training with regard to pediatric dermatology education and can increase dermatology residents’ comfort level with children. In a survey of a group of graduating third-year dermatology residents, dermatology residency program directors, and pediatric dermatology fellowship program directors by Nijhawan et al,⁵ residents who were trained in a program with one or more full-time pediatric dermatologists were more likely to feel competent treating children and to feel satisfied with their training program’s pediatric dermatology curriculum than residents without contact with a full-time pediatric dermatologist (50.0% vs 5.9% [P=.002] and 85.3% vs 52.9% [P<.001], respectively). The availability of a pediatric dermatology fellowship further enhanced satisfaction. Residents in programs with no full-time pediatric dermatologist on staff were more likely to be somewhat or extremely dissatisfied with their pediatric dermatology training. Residency program directors were more satisfied with their curriculums when there was one or more pediatric dermatologist on staff (P<.01).⁵

Programs with pediatric dermatologists also offer easy access to a mentor in the field. In a 2010 survey of pediatric dermatologists (published in 2014), Admani et al⁶ reported that 84% (91/109) of respondents (board-certified pediatric dermatologists) cited mentorship as the most important factor influencing their career choice. Exposure to the specialty was noted as a key motivating factor. In my opinion, the actual inclusion of a pediatric dermatology fellowship, whether the position is filled or not, appears to increase the chances of expansion and retention in the field. In the 2014 SPD workforce survey, more than 62% (61/98) of respondents were fellowship trained.⁷ In 2004 there were only 6 pediatric dermatology fellowship training programs. We have come quite far now with 36 fellowships as of August 12, 2018.⁸ The cost of education of course is not simple when pediatric dermatology fellowships are unfunded by the Accreditation Council for Graduate Medical Education; however, it is clear that the initial investment can create ongoing returns in pediatric dermatology.

Furthermore, due to the outpatient burden of skin disease in a pediatrics practice, providing pediatric trainees with contact with a pediatric dermatologist is needed. Prindaville et al⁹ performed a review from 2006 through 2010 of the National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey databases, which revealed that 9% of 23 million pediatric visits during this time period were for dermatologic diseases; therefore, knowledge of pediatric dermatology is vital to pediatrician training.

As if there was not enough evidence that pediatric dermatologists are in high demand, SPD pediatric dermatology workforce surveys from the last 5 years, which will soon be updated, show similar indications.^7,10 Fogel and Teng¹¹ showed that 60% of surveyed pediatric dermatologists (N=226) were academic and 81% were salaried. Unlike previous data,¹ the investigators showed that children constituted 79.5% of respondents’ patient populations. The academic practice environment favored by the majority of pediatric dermatologists was associated with seeing fewer patients per week and longer wait times (approximately 60 days for a pediatric dermatologist vs 15 days in other practice environments).¹¹ Therefore, the demand continues to be unmet even in many institutions with pediatric dermatology practitioners in place.

For the medical student or resident seeking a career in pediatric dermatology, it appears that finding and working on projects with mentors likely is the key to stepping in the field. From my own experience, pediatric dermatologists are extremely friendly and open to supporting career development in earnest students. Reach out to potential mentors months before starting desired electives, as you are competing with other students and pediatrics, dermatology, and emergency medicine residents. Joining and attending meetings of the SPD is a great way to find direction in this friendly and collegial field. Additionally, pediatric dermatology sessions at the annual meetings of the American Academy of Dermatology are a wonderful way to experience the excitement of the field. As a pediatric dermatologist in practice for almost 2 decades, I can honestly say that the field is always intellectually stimulating and evolving rapidly through enhanced understanding of disease pathogenesis, genetics, and therapeutics. Helping children and their parents/guardians never gets boring.

The solution to improving the size and accessibility of the pediatric dermatology workforce is not simple and likely starts from the bottom up. More than 75% of pediatric dermatologists favor implementing systems to encourage medical students to pursue a career in pediatric dermatology.⁷ Increasing resident exposure to dedicated pediatric dermatology training time enhances satisfaction.⁵ Increased funding of fellowships can help these students and residents meet their goals. Current fellowship training programs now total 36, but not all approved institutions have been able to support a postgraduate year 5 (PGY-5) or higher fellow, and in my experience some institutions have avoided adding a fellow due to lack of funding internally. The average pediatric dermatologist earns $100,000 less than colleagues who treat adults, which is an impediment to the expansion of the field.¹⁰ This disparity may chase away practitioners, especially those with medical school debt. Debt forgiveness programs, enhanced practice development, and better base pay for pediatric dermatologists could positively impact growth in this specialty. Dermatology and pediatrics training programs need to dedicate more money and developmental support for pediatric dermatologists as a way to invest in the quality of pediatric dermatology education for their trainees. By recognizing the true value of the academic contributions of pediatric dermatologists, dermatology residency programs can invest in producing trainees with greater aplomb and acumen in pediatric dermatology.

The Diagnosis: Self-healing Langerhans Cell Histiocytosis

Histopathologic examination showed an infiltrate of mononuclear cells with indented nuclei admixed with a variable dermal inflammatory infiltrate. Immunohistochemistry demonstrated cells that were strongly positive for CD1a (Figure, A) and langerin (Figure, B) antigens as well as S-100 protein (Figure, C), which was consistent with Langerhans cell histiocytosis (LCH).

Histiocytoses are a heterogeneous group of disorders in which the infiltrating cells belong to the mononuclear phagocyte system.^1,2 Langerhans cell histiocytosis is the most common dendritic cell-related histiocytosis, occurring in approximately 5 per 1 million children annually, giving it an incidence comparable to pediatric Hodgkin lymphoma and acute myeloid leukemia.^1,2

Historically, there has been much debate about the pathogenesis of the disease.² Until recently it was unknown whether LCH was primarily a neoplastic or an inflammatory disorder. Although the condition initially was thought to have a reactive etiology,¹ more recent evidence suggests a clonal neoplastic process. Langerhans cell histiocytosis lesions are clonal and display malignancy-associated mechanisms such as immune evasion. Genome sequencing has revealed several mutations in precursor myeloid cells that result in the common downstream hyperactivation of the mitogen-activated protein kinase signaling pathway that regulates cell proliferation and differentiation.¹

Langerhans cell histiocytosis displays a wide spectrum of clinical phenotypes, which historically were subclassified as eosinophilic granulomas (localized lesions in bone), Hand-Schüller-Christian disease (multiple organ involvement with the classic triad of skull defects, diabetes insipidus, and exophthalmos), and Letterer-Siwe disease (visceral lesions involving multiple organs).³ However, in 1997 the Reclassification Working Group of the Histiocyte Society redefined LCH as single-system single site (SS-s) LCH, single-system multisite LCH, and multisystem LCH.⁴

In SS-s LCH, the most common site is bone (82%), followed by the skin (12%).⁵ Skin SS-s LCH classically presents as multiple skin lesions at birth without systemic manifestations; the lesions spontaneously involute within a few months.⁶ Less commonly, skin SS-s LCH can present as a single lesion. Berger et al⁷ described 4 neonates with unilesional skin SS-s LCH. Since then, more than 30 cases have been reported in the literature,⁸ and we report herein another unilesional self-healing LCH.

The morphology of skin lesions in self-healing LCH is highly variable, with the most common being multiple erythematous crusted papules (50%), followed by eczematous scaly lesions resembling seborrheic dermatitis in intertriginous areas (37.5%).^3,6 Unilesional self-healing LCH typically presents as an ulcerated or crusted nodule or papule on the trunk. This variability results in a large differential diagnosis. Self-healing LCH is easily mistaken for infectious processes including neonatal herpes simplex and varicella-zoster virus infection.⁹ Often, the dermatology department is consulted to rule out LCH when the asymptomatic neonate does not respond to parenteral acyclovir.

Less commonly, the magenta-colored papulonodules of self-healing LCH can mimic blueberry muffin rash and mandate a workup for intrauterine infections, especially cytomegalovirus, rubella, and blood dyscrasia.¹⁰ Other noninfectious processes in the differential of self-healing LCH include congenital infantile hemangioma, neonatal lupus erythematosus, seborrheic dermatitis (cradle cap), pyogenic granuloma, and psoriasis.^3,10 Definitive diagnosis requires histopathology.

Because unilesional self-healing LCH has an excellent prognosis and usually resolves on its own, therapy is unnecessary.^3,8 One large retrospective study (N=146) found that of all patients with skin lesions, 56% were managed with biopsy only.⁵ Other options include watchful waiting and topical corticosteroids. If the skin lesions are large, ulcerated, and/or painful, alkylating antitumor agents have been used. For extensive cutaneous disease, systemic corticosteroids combined with chemotherapy and psoralen plus UVA can be effective.⁶

The primary concern in the management of self-healing LCH is that the solitary skin lesion may be the harbinger of an aggressive disorder that can progress to systemic disease.⁵ Moreover, recurrent visceral or disseminated disease may occur months to years after resolution of solitary skin lesions.⁹ Studies have shown that localized and disseminated disease cannot be differentiated on the basis of clinical findings, histology, immunohistochemistry, or biomarkers.^3,11 As a result, an evaluation for systemic disease should be performed at the time of diagnosis for cutaneous LCH.^3,9 Minimum baseline studies recommended by the Writing Group of the Histiocyte Society include a complete blood cell count, liver function tests, coagulation studies, chest radiography, skeletal surveys, and urine osmolality testing.¹² Periodic clinical follow-up is recommended for all variants of LCH.⁹

Our case was diagnosed as self-healing LCH based on histologic findings. No treatment was required, and at 3-month follow-up the infant was asymptomatic without recurrence and was meeting all developmental milestones.

The Diagnosis: Self-healing Langerhans Cell Histiocytosis

Histopathologic examination showed an infiltrate of mononuclear cells with indented nuclei admixed with a variable dermal inflammatory infiltrate. Immunohistochemistry demonstrated cells that were strongly positive for CD1a (Figure, A) and langerin (Figure, B) antigens as well as S-100 protein (Figure, C), which was consistent with Langerhans cell histiocytosis (LCH).

Histiocytoses are a heterogeneous group of disorders in which the infiltrating cells belong to the mononuclear phagocyte system.^1,2 Langerhans cell histiocytosis is the most common dendritic cell-related histiocytosis, occurring in approximately 5 per 1 million children annually, giving it an incidence comparable to pediatric Hodgkin lymphoma and acute myeloid leukemia.^1,2

Historically, there has been much debate about the pathogenesis of the disease.² Until recently it was unknown whether LCH was primarily a neoplastic or an inflammatory disorder. Although the condition initially was thought to have a reactive etiology,¹ more recent evidence suggests a clonal neoplastic process. Langerhans cell histiocytosis lesions are clonal and display malignancy-associated mechanisms such as immune evasion. Genome sequencing has revealed several mutations in precursor myeloid cells that result in the common downstream hyperactivation of the mitogen-activated protein kinase signaling pathway that regulates cell proliferation and differentiation.¹

Langerhans cell histiocytosis displays a wide spectrum of clinical phenotypes, which historically were subclassified as eosinophilic granulomas (localized lesions in bone), Hand-Schüller-Christian disease (multiple organ involvement with the classic triad of skull defects, diabetes insipidus, and exophthalmos), and Letterer-Siwe disease (visceral lesions involving multiple organs).³ However, in 1997 the Reclassification Working Group of the Histiocyte Society redefined LCH as single-system single site (SS-s) LCH, single-system multisite LCH, and multisystem LCH.⁴

In SS-s LCH, the most common site is bone (82%), followed by the skin (12%).⁵ Skin SS-s LCH classically presents as multiple skin lesions at birth without systemic manifestations; the lesions spontaneously involute within a few months.⁶ Less commonly, skin SS-s LCH can present as a single lesion. Berger et al⁷ described 4 neonates with unilesional skin SS-s LCH. Since then, more than 30 cases have been reported in the literature,⁸ and we report herein another unilesional self-healing LCH.

The morphology of skin lesions in self-healing LCH is highly variable, with the most common being multiple erythematous crusted papules (50%), followed by eczematous scaly lesions resembling seborrheic dermatitis in intertriginous areas (37.5%).^3,6 Unilesional self-healing LCH typically presents as an ulcerated or crusted nodule or papule on the trunk. This variability results in a large differential diagnosis. Self-healing LCH is easily mistaken for infectious processes including neonatal herpes simplex and varicella-zoster virus infection.⁹ Often, the dermatology department is consulted to rule out LCH when the asymptomatic neonate does not respond to parenteral acyclovir.

Less commonly, the magenta-colored papulonodules of self-healing LCH can mimic blueberry muffin rash and mandate a workup for intrauterine infections, especially cytomegalovirus, rubella, and blood dyscrasia.¹⁰ Other noninfectious processes in the differential of self-healing LCH include congenital infantile hemangioma, neonatal lupus erythematosus, seborrheic dermatitis (cradle cap), pyogenic granuloma, and psoriasis.^3,10 Definitive diagnosis requires histopathology.

Because unilesional self-healing LCH has an excellent prognosis and usually resolves on its own, therapy is unnecessary.^3,8 One large retrospective study (N=146) found that of all patients with skin lesions, 56% were managed with biopsy only.⁵ Other options include watchful waiting and topical corticosteroids. If the skin lesions are large, ulcerated, and/or painful, alkylating antitumor agents have been used. For extensive cutaneous disease, systemic corticosteroids combined with chemotherapy and psoralen plus UVA can be effective.⁶

The primary concern in the management of self-healing LCH is that the solitary skin lesion may be the harbinger of an aggressive disorder that can progress to systemic disease.⁵ Moreover, recurrent visceral or disseminated disease may occur months to years after resolution of solitary skin lesions.⁹ Studies have shown that localized and disseminated disease cannot be differentiated on the basis of clinical findings, histology, immunohistochemistry, or biomarkers.^3,11 As a result, an evaluation for systemic disease should be performed at the time of diagnosis for cutaneous LCH.^3,9 Minimum baseline studies recommended by the Writing Group of the Histiocyte Society include a complete blood cell count, liver function tests, coagulation studies, chest radiography, skeletal surveys, and urine osmolality testing.¹² Periodic clinical follow-up is recommended for all variants of LCH.⁹

Our case was diagnosed as self-healing LCH based on histologic findings. No treatment was required, and at 3-month follow-up the infant was asymptomatic without recurrence and was meeting all developmental milestones.

The Diagnosis: Self-healing Langerhans Cell Histiocytosis

Histopathologic examination showed an infiltrate of mononuclear cells with indented nuclei admixed with a variable dermal inflammatory infiltrate. Immunohistochemistry demonstrated cells that were strongly positive for CD1a (Figure, A) and langerin (Figure, B) antigens as well as S-100 protein (Figure, C), which was consistent with Langerhans cell histiocytosis (LCH).

Histiocytoses are a heterogeneous group of disorders in which the infiltrating cells belong to the mononuclear phagocyte system.^1,2 Langerhans cell histiocytosis is the most common dendritic cell-related histiocytosis, occurring in approximately 5 per 1 million children annually, giving it an incidence comparable to pediatric Hodgkin lymphoma and acute myeloid leukemia.^1,2

Historically, there has been much debate about the pathogenesis of the disease.² Until recently it was unknown whether LCH was primarily a neoplastic or an inflammatory disorder. Although the condition initially was thought to have a reactive etiology,¹ more recent evidence suggests a clonal neoplastic process. Langerhans cell histiocytosis lesions are clonal and display malignancy-associated mechanisms such as immune evasion. Genome sequencing has revealed several mutations in precursor myeloid cells that result in the common downstream hyperactivation of the mitogen-activated protein kinase signaling pathway that regulates cell proliferation and differentiation.¹

Langerhans cell histiocytosis displays a wide spectrum of clinical phenotypes, which historically were subclassified as eosinophilic granulomas (localized lesions in bone), Hand-Schüller-Christian disease (multiple organ involvement with the classic triad of skull defects, diabetes insipidus, and exophthalmos), and Letterer-Siwe disease (visceral lesions involving multiple organs).³ However, in 1997 the Reclassification Working Group of the Histiocyte Society redefined LCH as single-system single site (SS-s) LCH, single-system multisite LCH, and multisystem LCH.⁴

In SS-s LCH, the most common site is bone (82%), followed by the skin (12%).⁵ Skin SS-s LCH classically presents as multiple skin lesions at birth without systemic manifestations; the lesions spontaneously involute within a few months.⁶ Less commonly, skin SS-s LCH can present as a single lesion. Berger et al⁷ described 4 neonates with unilesional skin SS-s LCH. Since then, more than 30 cases have been reported in the literature,⁸ and we report herein another unilesional self-healing LCH.

The morphology of skin lesions in self-healing LCH is highly variable, with the most common being multiple erythematous crusted papules (50%), followed by eczematous scaly lesions resembling seborrheic dermatitis in intertriginous areas (37.5%).^3,6 Unilesional self-healing LCH typically presents as an ulcerated or crusted nodule or papule on the trunk. This variability results in a large differential diagnosis. Self-healing LCH is easily mistaken for infectious processes including neonatal herpes simplex and varicella-zoster virus infection.⁹ Often, the dermatology department is consulted to rule out LCH when the asymptomatic neonate does not respond to parenteral acyclovir.

Less commonly, the magenta-colored papulonodules of self-healing LCH can mimic blueberry muffin rash and mandate a workup for intrauterine infections, especially cytomegalovirus, rubella, and blood dyscrasia.¹⁰ Other noninfectious processes in the differential of self-healing LCH include congenital infantile hemangioma, neonatal lupus erythematosus, seborrheic dermatitis (cradle cap), pyogenic granuloma, and psoriasis.^3,10 Definitive diagnosis requires histopathology.

Because unilesional self-healing LCH has an excellent prognosis and usually resolves on its own, therapy is unnecessary.^3,8 One large retrospective study (N=146) found that of all patients with skin lesions, 56% were managed with biopsy only.⁵ Other options include watchful waiting and topical corticosteroids. If the skin lesions are large, ulcerated, and/or painful, alkylating antitumor agents have been used. For extensive cutaneous disease, systemic corticosteroids combined with chemotherapy and psoralen plus UVA can be effective.⁶

The primary concern in the management of self-healing LCH is that the solitary skin lesion may be the harbinger of an aggressive disorder that can progress to systemic disease.⁵ Moreover, recurrent visceral or disseminated disease may occur months to years after resolution of solitary skin lesions.⁹ Studies have shown that localized and disseminated disease cannot be differentiated on the basis of clinical findings, histology, immunohistochemistry, or biomarkers.^3,11 As a result, an evaluation for systemic disease should be performed at the time of diagnosis for cutaneous LCH.^3,9 Minimum baseline studies recommended by the Writing Group of the Histiocyte Society include a complete blood cell count, liver function tests, coagulation studies, chest radiography, skeletal surveys, and urine osmolality testing.¹² Periodic clinical follow-up is recommended for all variants of LCH.⁹

Our case was diagnosed as self-healing LCH based on histologic findings. No treatment was required, and at 3-month follow-up the infant was asymptomatic without recurrence and was meeting all developmental milestones.

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The psychosocial impact of psoriasis is a critical component of disease burden. Psoriatic patients have high rates of depression and anxiety, problems at work, and difficulties with interpersonal relationships and intimacy.¹ A National Psoriasis Foundation (NPF) survey from 2003 to 2011 reported that psoriasis affects overall emotional well-being in 88% of patients and enjoyment of life in 82% of patients.²

The reasons for psychosocial burden stem from public misconceptions and disease stigma. A survey of 1005 individuals (age range, 16–64 years) about their perceptions of psoriasis revealed that 16.5% believed that psoriasis is contagious and 6.8% believed that psoriasis is related to personal hygiene.³ Fifty percent practiced discriminatory behavior toward psoriatic patients, including reluctance to shake hands (28.8%) and engage in sexual relations/intercourse (44.1%). Sixty-five percent of psoriatic patients felt their appearance is unsightly, and 73% felt self-conscious about having psoriasis.²

The psychosocial burden exists despite medical treatment of the disease. In a cross-sectional study of 1184 psoriatic patients, 70.2% had impaired quality of life (QOL) as measured by the dermatology life quality index (DLQI), even after receiving a 4-week treatment for psoriasis.⁴ Medical treatment of psoriasis is not enough; providers need to assess overall QOL and provide treatment and resources for these patients in addition to symptomatic management.

There have been many studies on the psychosocial burden of psoriasis, but few have focused on a dermatology resident’s role in addressing this issue. This article will review psychosocial domains—psychiatric comorbidities and social functioning including occupational functioning, interpersonal relationships, and sexual functioning— and discuss a dermatology resident’s role in assessing and addressing each of these areas.

Methods

A PubMed search of articles indexed for MEDLINE was conducted using the following terms: psoriasis, depression, anxiety, work productivity, sexual functioning, and interpersonal relationships. Selected articles covered prevalence, assessment, and management of each psychosocial domain.

Results

Psychiatric Comorbidities

Prevalence
A high prevalence of psychiatric comorbidities exists in psoriatic patients. In a study of 469,097 patients with psoriasis, depression was the third most prevalent comorbidity (17.91%), following hyperlipidemia (45.64%) and hypertension (42.19%).⁵ In a 10-year longitudinal, population-based, prospective cohort study, antidepressant prescriptions were twice as frequent in psoriatic patients (17.8%) compared to control (7.9%)(P<.001).⁶ In a meta-analysis of 98 studies investigating psoriatic patients and psychiatric comorbidities, patients with psoriasis were 1.5 times more likely to experience depression (odds ratio [OR]: 1.57; 95% CI, 1.40-1.76) and use antidepressants (OR: 4.24; 95% CI, 1.53-11.76) compared to control.⁷ Patients with psoriasis were more likely to attempt suicide (OR: 1.32; 95% CI, 1.14-1.54) and complete suicide (OR: 1.20; 95% CI, 1.04-1.39) compared to people without psoriasis.⁸ A 1-year cross-sectional study of 90 psoriatic patients reported 78.7% were diagnosed with depression and 76.7% were diagnosed with anxiety. Seventy-two percent reported both anxiety and depression, correlating with worse QOL (χ²=26.7; P<.05).⁹

Assessment
Psychiatric comorbidities are assessed using clinical judgment and formal screening questionnaires in research studies. Signs of depression in patients with psoriasis can manifest as poor treatment adherence and recurrent flares of psoriasis.^10,11 Psoriatic patients with psychiatric comorbidities were less likely to be adherent to treatment (risk ratio: 0.35; P<.003).¹⁰ The patient health questionnaire (PHQ) 9 and generalized anxiety disorder scale (GAD) 7 are validated and reliable questionnaires. The first 2 questions in PHQ-9 and GAD-7 screen for depression and anxiety, respectively.^12-14 These 2-question screens are practical in a fast-paced dermatology outpatient setting. Systematic questionnaires specifically targeting mood disorders may be more beneficial than the widely used DLQI, which may not adequately capture mood disorders. Over the course of 10 months, 607 patients with psoriasis were asked to fill out the PHQ-9, GAD-7, and DLQI. Thirty-eight percent of patients with major depressive disorder had a DLQI score lower than 10, while 46% of patients with generalized anxiety disorder had a DLQI score lower than 10.¹⁵ Other questionnaires, including the hospital anxiety and depression scale and Beck depression inventory, are valid instruments with high sensitivity but are commonly used for research purposes and may not be clinically feasible.¹⁶

Management
Dermatologists should refer patients with depression and/or anxiety to psychiatry. Interventions include pharmacologic and nonpharmacologic management. First-line therapy for depression and anxiety is a combination of selective serotonin reuptake inhibitors and cognitive behavioral therapy.¹⁷ In addition, providers can direct patients to online resources such as the NPF website, where patients with psoriasis can access information about the signs and symptoms of mood disorders and contact the patient navigation center for further help.¹⁸

Social Functioning

Occupational Prevalence
The NPF found that 92% of patients with psoriasis or psoriatic arthritis (PsA) surveyed between 2003 and 2011 cited their psoriasis as reason for unemployment.² In a survey of 43 patients asked about social and occupational functioning using the social and occupational assessment scale, 62.5% of psoriatic patients reported distress at work and 51.1% reported decreased efficiency at work.¹⁹ A national online survey that was conducted in France and issued to patients with and without psoriasis assessed overall QOL and work productivity using the work productivity and activity impairment questionnaire for psoriasis (WPAI-PSO). Of 714 patients with psoriasis and PsA, the latter had a 57.6% decrease in work productivity over 7 days compared to 27.9% in controls (P<.05).²⁰ Occupational impairment leads to lost wages and hinders advancement, further exacerbating the psychosocial burden of psoriasis.²¹

Occupational Assessment
Formal assessment of occupational function can be done with the WPAI-PSO, a 6-question valid instrument.²² Providers may look for risk factors associated with greater loss in work productivity to help identify and offer support for patients. Patients with increased severity of itching, pain, and scaling experienced a greater decrease in work productivity.^21,23 Patients with PsA warrant early detection and treatment because they experience greater physical restraints that can interfere with work activities. Of the 459 psoriatic patients without a prior diagnosis of PsA who filled out the PsA screening and evaluation questionnaire, 144 (31.4%) received a score of 44 or higher and were referred to rheumatology for further evaluation with the classification criteria for PsA. Nine percent of patients failed to be screened and remained undiagnosed with PsA.²⁴ In a study using the health assessment questionnaire to assess 400 patients with PsA, those with worse physical function due to joint pain and stiffness were less likely to remain employed (OR: 0.56; P=.02).²⁵

Occupational Management
Identifying and coordinating symptoms of PsA between dermatology and rheumatology is beneficial for patients who experience debilitating symptoms. There are a variety of treatments available for PsA. According to the European League Against Rheumatism 2015 guidelines developed from expert opinion and systematic reviews for PsA management, there are 4 phases of treatment, with reassessment every 3 to 6 months for effectiveness of therapy.^26,27 Phase I involves initiating nonsteroidal anti-inflammatory drugs with or without glucocorticoid injections. Phase II involves synthetic disease-modifying drugs, including methotrexate, leflunomide, sulfasalazine, or cyclosporine. Phase III involves adding a second synthetic disease-modifying drug or starting a biologic, such as an anti–tumor necrosis factor, IL-12/IL-23, or IL-17 inhibitor. Phase IV involves switching to a different drug in either aforementioned class.^26,27 Treatment with biologics improves work productivity as assessed by WPAI-PSO for psoriasis and PsA.^28-30 Encouraging patients to speak up in the workplace and request small accommodations such as timely breaks or ergonomic chairs can help patients feel more comfortable and supported in the work environment.¹⁸ Patients who felt supported at work were more likely to remain employed.²⁵

Interpersonal Relationships Prevalence
Misinformation about psoriasis, fear of rejection, and feelings of isolation may contribute to interpersonal conflict. Patients have feelings of shame and self-consciousness that hinder them from engaging in social activities and seeking out relationships.³¹ Twenty-nine percent of patients feel that psoriasis has interfered with establishing relationships because of negative self-esteem associated with the disease,³² and 26.3% have experienced people avoiding physical contact.³³ Family and spouses of patients with psoriasis may be secondarily affected due to economic and emotional distress. Ninety-eight percent of family members of psoriatic patients experienced emotional distress and 54% experienced the burden of care.³⁴ In a survey of 63 relatives and partners of patients with psoriasis, 57% experienced psychological distress, including anxiety and worry over a psoriatic patient’s future.³⁵

Interpersonal Relationships Assessment
Current available tools, including the DLQI and short form health survey, measure overall QOL, including social functioning, but may not be practical in a clinic setting. Although no quick-screening test to assess for this domain exists, providers are encouraged to ask patients about disease impact on interpersonal relationships. The family DLQI questionnaire, adapted from the DLQI, may help physicians and social workers evaluate the burden on a patient’s family members.³⁴

Interpersonal Relationships Management
It may be difficult for providers to address problems with interpersonal relationships without accessible tools. Patients may not be accompanied by family or friends during appointments, and it is difficult to screen for these issues during visits. Providers may offer resources such as the NPF website, which provides information about support groups. It also provides tips on dating and connecting to others in the community who share similar experiences.¹⁸ Encouraging patients to seek family or couples therapy also may be beneficial. Increased social support can lead to better QOL and fewer depressive symptoms.³⁶

Sexual Functioning Prevalence
Psoriasis affects both physical and psychological components of sexual function. Among 3485 patients with skin conditions who were surveyed about sexual function, 34% of psoriatic patients reported that psoriasis interfered with sexual functioning at least to a certain degree.³⁷ Sexual impairment was strongly associated with depression, anxiety, and suicidal ideation; 24% of depressed patients and 20% of anxious patients experienced sexual problems a lot or very much, based on the DLQI.³⁷ Depending on the questionnaire used, the prevalence of sexual dysfunction due to psoriasis ranged from 35.5% to 71.3%.³⁸ In an observational cohort study of 158 participants (n=79 psoriasis patients and n=79 controls), 34.2% of patients with psoriasis experienced erectile dysfunction compared to 17.7% of controls.³⁹ Forty-two percent of psoriatic patients with genital involvement reported dyspareunia, 32% reported worsening of genital psoriasis after intercourse, and 43% reported decreased frequency of intercourse.⁴⁰

Sexual Functioning Assessment
The Skindex-29, DLQI, and psoriasis disability index are available QOL tools that include one question evaluating difficulties with sexual function. The Massachusetts General Hospital sexual functioning questionnaire is a 5-item validated tool that specifically assesses sexual dysfunction.⁴¹ Distribution of lesions can help identify patients who are more likely to experience sexual dysfunction. In 160 patients who completed the questionnaire and self-reported psoriasis area and severity index, lesions on the abdomen, genitals, lumbar region, and buttocks were associated with worse sexual functioning (OR: 7.9; 95% CI, 2.3-33.4; P<.05).⁴² Dermatologists could assess for sexual problems using either formal questionnaires or direct conversations during the routine psoriasis visit, as patients may be suffering in silence due to this sensitive topic.

Sexual Functioning Management
Better disease control leads to improved sexual function, as patients experience fewer feelings of shame, anxiety, and depression, as well as improvement of physical symptoms that can interfere with sexual functioning.^38,43,44 Reducing friction, warmth, and moisture, as well as avoiding tight clothing, can help those with genital psoriasis. Patients are advised to reapply topical medications after sexual intercourse. Patients also can apply makeup to disguise psoriasis and help reduce feelings of self-consciousness that can impede sexual intimacy.¹⁸

Comment

The psychosocial burden of psoriasis penetrates many facets of patient lives. Psoriasis can invoke feelings of shame and embarrassment that are worsened by the public’s misconceptions about psoriasis, resulting in serious mental health issues that can cause even greater disability. Depression and anxiety are prevalent in patients with psoriasis. The characteristic symptoms of pain and pruritus along with psychiatric comorbidities can have an underestimated impact on daily activities, including employment, interpersonal relationships, and sexual function. Such dysfunctions have serious implications toward wages, professional advancement, social support, and overall QOL.

Dermatology providers play an important role in screening for these problems through validated questionnaires and identifying risks. Simple screening questions such as the PHQ-9 can be beneficial and feasible during dermatology visits. Screening for PsA can help patients avoid problems at work. Sexual dysfunction is a sensitive topic; however, providers can use a 1-question screen from valid questionnaires and inquire about the location of lesions as opportunities to address this issue.

Interventions lead to better disease control, which concurrently improves overall QOL. These interventions depend on both patient adherence and a physician’s commitment to finding an optimal treatment regimen for each individual. Medical management; coordinating care; developing treatment plans with psychiatry, rheumatology, and primary care providers; and psychological counseling and services may be necessary and beneficial (Table). Offering accessible resources such as the NPF website helps patients access information outside the clinic when it is not feasible to address all these concerns in a single visit. Psoriasis requires more than just medical management; it requires dermatology providers to use a multidisciplinary approach to address the psychosocial aspects of the disease.

Conclusion

The psychosocial burden of psoriasis is immense. Stigma, public misconception, mental health concerns, and occupational and interpersonal difficulty are the basis of disease burden. Providers play a vital role in assessing the effect psoriasis has on different areas of patients’ lives and providing appropriate interventions and resources to reduce disease burden.

The psychosocial impact of psoriasis is a critical component of disease burden. Psoriatic patients have high rates of depression and anxiety, problems at work, and difficulties with interpersonal relationships and intimacy.¹ A National Psoriasis Foundation (NPF) survey from 2003 to 2011 reported that psoriasis affects overall emotional well-being in 88% of patients and enjoyment of life in 82% of patients.²

The reasons for psychosocial burden stem from public misconceptions and disease stigma. A survey of 1005 individuals (age range, 16–64 years) about their perceptions of psoriasis revealed that 16.5% believed that psoriasis is contagious and 6.8% believed that psoriasis is related to personal hygiene.³ Fifty percent practiced discriminatory behavior toward psoriatic patients, including reluctance to shake hands (28.8%) and engage in sexual relations/intercourse (44.1%). Sixty-five percent of psoriatic patients felt their appearance is unsightly, and 73% felt self-conscious about having psoriasis.²

The psychosocial burden exists despite medical treatment of the disease. In a cross-sectional study of 1184 psoriatic patients, 70.2% had impaired quality of life (QOL) as measured by the dermatology life quality index (DLQI), even after receiving a 4-week treatment for psoriasis.⁴ Medical treatment of psoriasis is not enough; providers need to assess overall QOL and provide treatment and resources for these patients in addition to symptomatic management.

There have been many studies on the psychosocial burden of psoriasis, but few have focused on a dermatology resident’s role in addressing this issue. This article will review psychosocial domains—psychiatric comorbidities and social functioning including occupational functioning, interpersonal relationships, and sexual functioning— and discuss a dermatology resident’s role in assessing and addressing each of these areas.

Methods

A PubMed search of articles indexed for MEDLINE was conducted using the following terms: psoriasis, depression, anxiety, work productivity, sexual functioning, and interpersonal relationships. Selected articles covered prevalence, assessment, and management of each psychosocial domain.

Results

Psychiatric Comorbidities

Prevalence
A high prevalence of psychiatric comorbidities exists in psoriatic patients. In a study of 469,097 patients with psoriasis, depression was the third most prevalent comorbidity (17.91%), following hyperlipidemia (45.64%) and hypertension (42.19%).⁵ In a 10-year longitudinal, population-based, prospective cohort study, antidepressant prescriptions were twice as frequent in psoriatic patients (17.8%) compared to control (7.9%)(P<.001).⁶ In a meta-analysis of 98 studies investigating psoriatic patients and psychiatric comorbidities, patients with psoriasis were 1.5 times more likely to experience depression (odds ratio [OR]: 1.57; 95% CI, 1.40-1.76) and use antidepressants (OR: 4.24; 95% CI, 1.53-11.76) compared to control.⁷ Patients with psoriasis were more likely to attempt suicide (OR: 1.32; 95% CI, 1.14-1.54) and complete suicide (OR: 1.20; 95% CI, 1.04-1.39) compared to people without psoriasis.⁸ A 1-year cross-sectional study of 90 psoriatic patients reported 78.7% were diagnosed with depression and 76.7% were diagnosed with anxiety. Seventy-two percent reported both anxiety and depression, correlating with worse QOL (χ²=26.7; P<.05).⁹

Assessment
Psychiatric comorbidities are assessed using clinical judgment and formal screening questionnaires in research studies. Signs of depression in patients with psoriasis can manifest as poor treatment adherence and recurrent flares of psoriasis.^10,11 Psoriatic patients with psychiatric comorbidities were less likely to be adherent to treatment (risk ratio: 0.35; P<.003).¹⁰ The patient health questionnaire (PHQ) 9 and generalized anxiety disorder scale (GAD) 7 are validated and reliable questionnaires. The first 2 questions in PHQ-9 and GAD-7 screen for depression and anxiety, respectively.^12-14 These 2-question screens are practical in a fast-paced dermatology outpatient setting. Systematic questionnaires specifically targeting mood disorders may be more beneficial than the widely used DLQI, which may not adequately capture mood disorders. Over the course of 10 months, 607 patients with psoriasis were asked to fill out the PHQ-9, GAD-7, and DLQI. Thirty-eight percent of patients with major depressive disorder had a DLQI score lower than 10, while 46% of patients with generalized anxiety disorder had a DLQI score lower than 10.¹⁵ Other questionnaires, including the hospital anxiety and depression scale and Beck depression inventory, are valid instruments with high sensitivity but are commonly used for research purposes and may not be clinically feasible.¹⁶

Management
Dermatologists should refer patients with depression and/or anxiety to psychiatry. Interventions include pharmacologic and nonpharmacologic management. First-line therapy for depression and anxiety is a combination of selective serotonin reuptake inhibitors and cognitive behavioral therapy.¹⁷ In addition, providers can direct patients to online resources such as the NPF website, where patients with psoriasis can access information about the signs and symptoms of mood disorders and contact the patient navigation center for further help.¹⁸

Social Functioning

Occupational Prevalence
The NPF found that 92% of patients with psoriasis or psoriatic arthritis (PsA) surveyed between 2003 and 2011 cited their psoriasis as reason for unemployment.² In a survey of 43 patients asked about social and occupational functioning using the social and occupational assessment scale, 62.5% of psoriatic patients reported distress at work and 51.1% reported decreased efficiency at work.¹⁹ A national online survey that was conducted in France and issued to patients with and without psoriasis assessed overall QOL and work productivity using the work productivity and activity impairment questionnaire for psoriasis (WPAI-PSO). Of 714 patients with psoriasis and PsA, the latter had a 57.6% decrease in work productivity over 7 days compared to 27.9% in controls (P<.05).²⁰ Occupational impairment leads to lost wages and hinders advancement, further exacerbating the psychosocial burden of psoriasis.²¹

Occupational Assessment
Formal assessment of occupational function can be done with the WPAI-PSO, a 6-question valid instrument.²² Providers may look for risk factors associated with greater loss in work productivity to help identify and offer support for patients. Patients with increased severity of itching, pain, and scaling experienced a greater decrease in work productivity.^21,23 Patients with PsA warrant early detection and treatment because they experience greater physical restraints that can interfere with work activities. Of the 459 psoriatic patients without a prior diagnosis of PsA who filled out the PsA screening and evaluation questionnaire, 144 (31.4%) received a score of 44 or higher and were referred to rheumatology for further evaluation with the classification criteria for PsA. Nine percent of patients failed to be screened and remained undiagnosed with PsA.²⁴ In a study using the health assessment questionnaire to assess 400 patients with PsA, those with worse physical function due to joint pain and stiffness were less likely to remain employed (OR: 0.56; P=.02).²⁵

Occupational Management
Identifying and coordinating symptoms of PsA between dermatology and rheumatology is beneficial for patients who experience debilitating symptoms. There are a variety of treatments available for PsA. According to the European League Against Rheumatism 2015 guidelines developed from expert opinion and systematic reviews for PsA management, there are 4 phases of treatment, with reassessment every 3 to 6 months for effectiveness of therapy.^26,27 Phase I involves initiating nonsteroidal anti-inflammatory drugs with or without glucocorticoid injections. Phase II involves synthetic disease-modifying drugs, including methotrexate, leflunomide, sulfasalazine, or cyclosporine. Phase III involves adding a second synthetic disease-modifying drug or starting a biologic, such as an anti–tumor necrosis factor, IL-12/IL-23, or IL-17 inhibitor. Phase IV involves switching to a different drug in either aforementioned class.^26,27 Treatment with biologics improves work productivity as assessed by WPAI-PSO for psoriasis and PsA.^28-30 Encouraging patients to speak up in the workplace and request small accommodations such as timely breaks or ergonomic chairs can help patients feel more comfortable and supported in the work environment.¹⁸ Patients who felt supported at work were more likely to remain employed.²⁵

Interpersonal Relationships Prevalence
Misinformation about psoriasis, fear of rejection, and feelings of isolation may contribute to interpersonal conflict. Patients have feelings of shame and self-consciousness that hinder them from engaging in social activities and seeking out relationships.³¹ Twenty-nine percent of patients feel that psoriasis has interfered with establishing relationships because of negative self-esteem associated with the disease,³² and 26.3% have experienced people avoiding physical contact.³³ Family and spouses of patients with psoriasis may be secondarily affected due to economic and emotional distress. Ninety-eight percent of family members of psoriatic patients experienced emotional distress and 54% experienced the burden of care.³⁴ In a survey of 63 relatives and partners of patients with psoriasis, 57% experienced psychological distress, including anxiety and worry over a psoriatic patient’s future.³⁵

Interpersonal Relationships Assessment
Current available tools, including the DLQI and short form health survey, measure overall QOL, including social functioning, but may not be practical in a clinic setting. Although no quick-screening test to assess for this domain exists, providers are encouraged to ask patients about disease impact on interpersonal relationships. The family DLQI questionnaire, adapted from the DLQI, may help physicians and social workers evaluate the burden on a patient’s family members.³⁴

Interpersonal Relationships Management
It may be difficult for providers to address problems with interpersonal relationships without accessible tools. Patients may not be accompanied by family or friends during appointments, and it is difficult to screen for these issues during visits. Providers may offer resources such as the NPF website, which provides information about support groups. It also provides tips on dating and connecting to others in the community who share similar experiences.¹⁸ Encouraging patients to seek family or couples therapy also may be beneficial. Increased social support can lead to better QOL and fewer depressive symptoms.³⁶

Sexual Functioning Prevalence
Psoriasis affects both physical and psychological components of sexual function. Among 3485 patients with skin conditions who were surveyed about sexual function, 34% of psoriatic patients reported that psoriasis interfered with sexual functioning at least to a certain degree.³⁷ Sexual impairment was strongly associated with depression, anxiety, and suicidal ideation; 24% of depressed patients and 20% of anxious patients experienced sexual problems a lot or very much, based on the DLQI.³⁷ Depending on the questionnaire used, the prevalence of sexual dysfunction due to psoriasis ranged from 35.5% to 71.3%.³⁸ In an observational cohort study of 158 participants (n=79 psoriasis patients and n=79 controls), 34.2% of patients with psoriasis experienced erectile dysfunction compared to 17.7% of controls.³⁹ Forty-two percent of psoriatic patients with genital involvement reported dyspareunia, 32% reported worsening of genital psoriasis after intercourse, and 43% reported decreased frequency of intercourse.⁴⁰

Sexual Functioning Assessment
The Skindex-29, DLQI, and psoriasis disability index are available QOL tools that include one question evaluating difficulties with sexual function. The Massachusetts General Hospital sexual functioning questionnaire is a 5-item validated tool that specifically assesses sexual dysfunction.⁴¹ Distribution of lesions can help identify patients who are more likely to experience sexual dysfunction. In 160 patients who completed the questionnaire and self-reported psoriasis area and severity index, lesions on the abdomen, genitals, lumbar region, and buttocks were associated with worse sexual functioning (OR: 7.9; 95% CI, 2.3-33.4; P<.05).⁴² Dermatologists could assess for sexual problems using either formal questionnaires or direct conversations during the routine psoriasis visit, as patients may be suffering in silence due to this sensitive topic.

Sexual Functioning Management
Better disease control leads to improved sexual function, as patients experience fewer feelings of shame, anxiety, and depression, as well as improvement of physical symptoms that can interfere with sexual functioning.^38,43,44 Reducing friction, warmth, and moisture, as well as avoiding tight clothing, can help those with genital psoriasis. Patients are advised to reapply topical medications after sexual intercourse. Patients also can apply makeup to disguise psoriasis and help reduce feelings of self-consciousness that can impede sexual intimacy.¹⁸

Comment

The psychosocial burden of psoriasis penetrates many facets of patient lives. Psoriasis can invoke feelings of shame and embarrassment that are worsened by the public’s misconceptions about psoriasis, resulting in serious mental health issues that can cause even greater disability. Depression and anxiety are prevalent in patients with psoriasis. The characteristic symptoms of pain and pruritus along with psychiatric comorbidities can have an underestimated impact on daily activities, including employment, interpersonal relationships, and sexual function. Such dysfunctions have serious implications toward wages, professional advancement, social support, and overall QOL.

Dermatology providers play an important role in screening for these problems through validated questionnaires and identifying risks. Simple screening questions such as the PHQ-9 can be beneficial and feasible during dermatology visits. Screening for PsA can help patients avoid problems at work. Sexual dysfunction is a sensitive topic; however, providers can use a 1-question screen from valid questionnaires and inquire about the location of lesions as opportunities to address this issue.

Interventions lead to better disease control, which concurrently improves overall QOL. These interventions depend on both patient adherence and a physician’s commitment to finding an optimal treatment regimen for each individual. Medical management; coordinating care; developing treatment plans with psychiatry, rheumatology, and primary care providers; and psychological counseling and services may be necessary and beneficial (Table). Offering accessible resources such as the NPF website helps patients access information outside the clinic when it is not feasible to address all these concerns in a single visit. Psoriasis requires more than just medical management; it requires dermatology providers to use a multidisciplinary approach to address the psychosocial aspects of the disease.

Conclusion

The psychosocial burden of psoriasis is immense. Stigma, public misconception, mental health concerns, and occupational and interpersonal difficulty are the basis of disease burden. Providers play a vital role in assessing the effect psoriasis has on different areas of patients’ lives and providing appropriate interventions and resources to reduce disease burden.

The psychosocial impact of psoriasis is a critical component of disease burden. Psoriatic patients have high rates of depression and anxiety, problems at work, and difficulties with interpersonal relationships and intimacy.¹ A National Psoriasis Foundation (NPF) survey from 2003 to 2011 reported that psoriasis affects overall emotional well-being in 88% of patients and enjoyment of life in 82% of patients.²

The reasons for psychosocial burden stem from public misconceptions and disease stigma. A survey of 1005 individuals (age range, 16–64 years) about their perceptions of psoriasis revealed that 16.5% believed that psoriasis is contagious and 6.8% believed that psoriasis is related to personal hygiene.³ Fifty percent practiced discriminatory behavior toward psoriatic patients, including reluctance to shake hands (28.8%) and engage in sexual relations/intercourse (44.1%). Sixty-five percent of psoriatic patients felt their appearance is unsightly, and 73% felt self-conscious about having psoriasis.²

The psychosocial burden exists despite medical treatment of the disease. In a cross-sectional study of 1184 psoriatic patients, 70.2% had impaired quality of life (QOL) as measured by the dermatology life quality index (DLQI), even after receiving a 4-week treatment for psoriasis.⁴ Medical treatment of psoriasis is not enough; providers need to assess overall QOL and provide treatment and resources for these patients in addition to symptomatic management.

There have been many studies on the psychosocial burden of psoriasis, but few have focused on a dermatology resident’s role in addressing this issue. This article will review psychosocial domains—psychiatric comorbidities and social functioning including occupational functioning, interpersonal relationships, and sexual functioning— and discuss a dermatology resident’s role in assessing and addressing each of these areas.

Methods

A PubMed search of articles indexed for MEDLINE was conducted using the following terms: psoriasis, depression, anxiety, work productivity, sexual functioning, and interpersonal relationships. Selected articles covered prevalence, assessment, and management of each psychosocial domain.

Results

Psychiatric Comorbidities

Prevalence
A high prevalence of psychiatric comorbidities exists in psoriatic patients. In a study of 469,097 patients with psoriasis, depression was the third most prevalent comorbidity (17.91%), following hyperlipidemia (45.64%) and hypertension (42.19%).⁵ In a 10-year longitudinal, population-based, prospective cohort study, antidepressant prescriptions were twice as frequent in psoriatic patients (17.8%) compared to control (7.9%)(P<.001).⁶ In a meta-analysis of 98 studies investigating psoriatic patients and psychiatric comorbidities, patients with psoriasis were 1.5 times more likely to experience depression (odds ratio [OR]: 1.57; 95% CI, 1.40-1.76) and use antidepressants (OR: 4.24; 95% CI, 1.53-11.76) compared to control.⁷ Patients with psoriasis were more likely to attempt suicide (OR: 1.32; 95% CI, 1.14-1.54) and complete suicide (OR: 1.20; 95% CI, 1.04-1.39) compared to people without psoriasis.⁸ A 1-year cross-sectional study of 90 psoriatic patients reported 78.7% were diagnosed with depression and 76.7% were diagnosed with anxiety. Seventy-two percent reported both anxiety and depression, correlating with worse QOL (χ²=26.7; P<.05).⁹

Assessment
Psychiatric comorbidities are assessed using clinical judgment and formal screening questionnaires in research studies. Signs of depression in patients with psoriasis can manifest as poor treatment adherence and recurrent flares of psoriasis.^10,11 Psoriatic patients with psychiatric comorbidities were less likely to be adherent to treatment (risk ratio: 0.35; P<.003).¹⁰ The patient health questionnaire (PHQ) 9 and generalized anxiety disorder scale (GAD) 7 are validated and reliable questionnaires. The first 2 questions in PHQ-9 and GAD-7 screen for depression and anxiety, respectively.^12-14 These 2-question screens are practical in a fast-paced dermatology outpatient setting. Systematic questionnaires specifically targeting mood disorders may be more beneficial than the widely used DLQI, which may not adequately capture mood disorders. Over the course of 10 months, 607 patients with psoriasis were asked to fill out the PHQ-9, GAD-7, and DLQI. Thirty-eight percent of patients with major depressive disorder had a DLQI score lower than 10, while 46% of patients with generalized anxiety disorder had a DLQI score lower than 10.¹⁵ Other questionnaires, including the hospital anxiety and depression scale and Beck depression inventory, are valid instruments with high sensitivity but are commonly used for research purposes and may not be clinically feasible.¹⁶

Management
Dermatologists should refer patients with depression and/or anxiety to psychiatry. Interventions include pharmacologic and nonpharmacologic management. First-line therapy for depression and anxiety is a combination of selective serotonin reuptake inhibitors and cognitive behavioral therapy.¹⁷ In addition, providers can direct patients to online resources such as the NPF website, where patients with psoriasis can access information about the signs and symptoms of mood disorders and contact the patient navigation center for further help.¹⁸

Social Functioning

Occupational Prevalence
The NPF found that 92% of patients with psoriasis or psoriatic arthritis (PsA) surveyed between 2003 and 2011 cited their psoriasis as reason for unemployment.² In a survey of 43 patients asked about social and occupational functioning using the social and occupational assessment scale, 62.5% of psoriatic patients reported distress at work and 51.1% reported decreased efficiency at work.¹⁹ A national online survey that was conducted in France and issued to patients with and without psoriasis assessed overall QOL and work productivity using the work productivity and activity impairment questionnaire for psoriasis (WPAI-PSO). Of 714 patients with psoriasis and PsA, the latter had a 57.6% decrease in work productivity over 7 days compared to 27.9% in controls (P<.05).²⁰ Occupational impairment leads to lost wages and hinders advancement, further exacerbating the psychosocial burden of psoriasis.²¹

Occupational Assessment
Formal assessment of occupational function can be done with the WPAI-PSO, a 6-question valid instrument.²² Providers may look for risk factors associated with greater loss in work productivity to help identify and offer support for patients. Patients with increased severity of itching, pain, and scaling experienced a greater decrease in work productivity.^21,23 Patients with PsA warrant early detection and treatment because they experience greater physical restraints that can interfere with work activities. Of the 459 psoriatic patients without a prior diagnosis of PsA who filled out the PsA screening and evaluation questionnaire, 144 (31.4%) received a score of 44 or higher and were referred to rheumatology for further evaluation with the classification criteria for PsA. Nine percent of patients failed to be screened and remained undiagnosed with PsA.²⁴ In a study using the health assessment questionnaire to assess 400 patients with PsA, those with worse physical function due to joint pain and stiffness were less likely to remain employed (OR: 0.56; P=.02).²⁵

Occupational Management
Identifying and coordinating symptoms of PsA between dermatology and rheumatology is beneficial for patients who experience debilitating symptoms. There are a variety of treatments available for PsA. According to the European League Against Rheumatism 2015 guidelines developed from expert opinion and systematic reviews for PsA management, there are 4 phases of treatment, with reassessment every 3 to 6 months for effectiveness of therapy.^26,27 Phase I involves initiating nonsteroidal anti-inflammatory drugs with or without glucocorticoid injections. Phase II involves synthetic disease-modifying drugs, including methotrexate, leflunomide, sulfasalazine, or cyclosporine. Phase III involves adding a second synthetic disease-modifying drug or starting a biologic, such as an anti–tumor necrosis factor, IL-12/IL-23, or IL-17 inhibitor. Phase IV involves switching to a different drug in either aforementioned class.^26,27 Treatment with biologics improves work productivity as assessed by WPAI-PSO for psoriasis and PsA.^28-30 Encouraging patients to speak up in the workplace and request small accommodations such as timely breaks or ergonomic chairs can help patients feel more comfortable and supported in the work environment.¹⁸ Patients who felt supported at work were more likely to remain employed.²⁵

Interpersonal Relationships Prevalence
Misinformation about psoriasis, fear of rejection, and feelings of isolation may contribute to interpersonal conflict. Patients have feelings of shame and self-consciousness that hinder them from engaging in social activities and seeking out relationships.³¹ Twenty-nine percent of patients feel that psoriasis has interfered with establishing relationships because of negative self-esteem associated with the disease,³² and 26.3% have experienced people avoiding physical contact.³³ Family and spouses of patients with psoriasis may be secondarily affected due to economic and emotional distress. Ninety-eight percent of family members of psoriatic patients experienced emotional distress and 54% experienced the burden of care.³⁴ In a survey of 63 relatives and partners of patients with psoriasis, 57% experienced psychological distress, including anxiety and worry over a psoriatic patient’s future.³⁵

Interpersonal Relationships Assessment
Current available tools, including the DLQI and short form health survey, measure overall QOL, including social functioning, but may not be practical in a clinic setting. Although no quick-screening test to assess for this domain exists, providers are encouraged to ask patients about disease impact on interpersonal relationships. The family DLQI questionnaire, adapted from the DLQI, may help physicians and social workers evaluate the burden on a patient’s family members.³⁴

Interpersonal Relationships Management
It may be difficult for providers to address problems with interpersonal relationships without accessible tools. Patients may not be accompanied by family or friends during appointments, and it is difficult to screen for these issues during visits. Providers may offer resources such as the NPF website, which provides information about support groups. It also provides tips on dating and connecting to others in the community who share similar experiences.¹⁸ Encouraging patients to seek family or couples therapy also may be beneficial. Increased social support can lead to better QOL and fewer depressive symptoms.³⁶

Sexual Functioning Prevalence
Psoriasis affects both physical and psychological components of sexual function. Among 3485 patients with skin conditions who were surveyed about sexual function, 34% of psoriatic patients reported that psoriasis interfered with sexual functioning at least to a certain degree.³⁷ Sexual impairment was strongly associated with depression, anxiety, and suicidal ideation; 24% of depressed patients and 20% of anxious patients experienced sexual problems a lot or very much, based on the DLQI.³⁷ Depending on the questionnaire used, the prevalence of sexual dysfunction due to psoriasis ranged from 35.5% to 71.3%.³⁸ In an observational cohort study of 158 participants (n=79 psoriasis patients and n=79 controls), 34.2% of patients with psoriasis experienced erectile dysfunction compared to 17.7% of controls.³⁹ Forty-two percent of psoriatic patients with genital involvement reported dyspareunia, 32% reported worsening of genital psoriasis after intercourse, and 43% reported decreased frequency of intercourse.⁴⁰

Sexual Functioning Assessment
The Skindex-29, DLQI, and psoriasis disability index are available QOL tools that include one question evaluating difficulties with sexual function. The Massachusetts General Hospital sexual functioning questionnaire is a 5-item validated tool that specifically assesses sexual dysfunction.⁴¹ Distribution of lesions can help identify patients who are more likely to experience sexual dysfunction. In 160 patients who completed the questionnaire and self-reported psoriasis area and severity index, lesions on the abdomen, genitals, lumbar region, and buttocks were associated with worse sexual functioning (OR: 7.9; 95% CI, 2.3-33.4; P<.05).⁴² Dermatologists could assess for sexual problems using either formal questionnaires or direct conversations during the routine psoriasis visit, as patients may be suffering in silence due to this sensitive topic.

Sexual Functioning Management
Better disease control leads to improved sexual function, as patients experience fewer feelings of shame, anxiety, and depression, as well as improvement of physical symptoms that can interfere with sexual functioning.^38,43,44 Reducing friction, warmth, and moisture, as well as avoiding tight clothing, can help those with genital psoriasis. Patients are advised to reapply topical medications after sexual intercourse. Patients also can apply makeup to disguise psoriasis and help reduce feelings of self-consciousness that can impede sexual intimacy.¹⁸

Comment

The psychosocial burden of psoriasis penetrates many facets of patient lives. Psoriasis can invoke feelings of shame and embarrassment that are worsened by the public’s misconceptions about psoriasis, resulting in serious mental health issues that can cause even greater disability. Depression and anxiety are prevalent in patients with psoriasis. The characteristic symptoms of pain and pruritus along with psychiatric comorbidities can have an underestimated impact on daily activities, including employment, interpersonal relationships, and sexual function. Such dysfunctions have serious implications toward wages, professional advancement, social support, and overall QOL.

Dermatology providers play an important role in screening for these problems through validated questionnaires and identifying risks. Simple screening questions such as the PHQ-9 can be beneficial and feasible during dermatology visits. Screening for PsA can help patients avoid problems at work. Sexual dysfunction is a sensitive topic; however, providers can use a 1-question screen from valid questionnaires and inquire about the location of lesions as opportunities to address this issue.

Interventions lead to better disease control, which concurrently improves overall QOL. These interventions depend on both patient adherence and a physician’s commitment to finding an optimal treatment regimen for each individual. Medical management; coordinating care; developing treatment plans with psychiatry, rheumatology, and primary care providers; and psychological counseling and services may be necessary and beneficial (Table). Offering accessible resources such as the NPF website helps patients access information outside the clinic when it is not feasible to address all these concerns in a single visit. Psoriasis requires more than just medical management; it requires dermatology providers to use a multidisciplinary approach to address the psychosocial aspects of the disease.

Conclusion

The psychosocial burden of psoriasis is immense. Stigma, public misconception, mental health concerns, and occupational and interpersonal difficulty are the basis of disease burden. Providers play a vital role in assessing the effect psoriasis has on different areas of patients’ lives and providing appropriate interventions and resources to reduce disease burden.

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.