Article

Click to view more from Pulmonology Data Trends 2024. 

Click to view more from Pulmonology Data Trends 2024. 

Click to view more from Pulmonology Data Trends 2024. 

The most likely diagnosis for this patient is veteran posttraumatic stress disorder (PTSD), given his history of combat exposure and symptoms, such as severe headaches, difficulty concentrating, mood swings, nightmares, flashbacks, increased startle response, and hypervigilance. MRI findings showing significant changes in the limbic system and hippocampal regions support this diagnosis. Other potential diagnoses, like traumatic brain injury, chronic migraine, and major depressive disorder, are less likely because of their inability to account for the full range of his symptoms and specific MRI abnormalities.

PTSD, experienced by a subset of individuals after exposure to life-threatening events, has a lifetime prevalence of 4%-7% and a current prevalence of 1%-3%, with higher rates in older women, those with more trauma, and combat veterans. Nearly half of US veterans are aged 65 or older, many being Vietnam-era veterans at elevated risk for PTSD. Prevalence rates in older veterans range between 1% and 22%.

PTSD is characterized by intrusive thoughts, flashbacks, nightmares, avoidance of reminders, hypervigilance, and sleep difficulties, significantly disrupting interpersonal and occupational functioning. Screening tools like the primary care (PC) PTSD-5 and PCL-5, used in primary care settings, are effective for early detection, provisional diagnosis, and monitoring of symptom changes. The clinician-administered PTSD scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition DSM-5 (CAPS-5) is the gold standard for diagnosis, particularly among veterans, with multimethod assessments combining self-report measures and semi-structured interviews recommended for accuracy. The DSM-5 criteria for PTSD diagnosis describe exposure to traumatic events, intrusion symptoms, avoidance behaviors, negative mood, and altered arousal, with symptoms persisting for over a month and causing significant distress or functional impairment. 

Research has identified consistent anatomical and functional changes in PTSD patients, such as smaller hippocampi, decreased corpus callosum and prefrontal cortex, increased amygdala reactivity, and decreased prefrontal cortex activity. PTSD, linked to alterations in brain regions involved in fear learning and memory, shows diminished structural integrity in executive function areas, reduced cortical volumes in the cingulate brain cortex and frontal regions, and reduced white matter integrity in key brain pathways. Neuroimaging findings, however, are primarily used for research currently and have yet to be widely implemented in clinical guidelines.

International PTSD treatment guidelines consistently recognize trauma-focused cognitive-behavioral therapies (CBTs), such as cognitive processing therapy (CPT), prolonged exposure (PE), and eye movement desensitization and reprocessing (EMDR) as the gold standard. Recent guidelines have expanded the list of recommended treatments: The 2023 Department of Veterans Affairs and Department of Defense guidelines in the United States also endorse therapies like written narrative exposure and brief eclectic therapy. Internationally, guidelines do not perfectly coincide, as the 2018 update from the United Kingdom's National Institute for Health and Care Excellence (NICE) gives the highest recommendations to PE and CPT but rates EMDR slightly lower for military veterans because of limited evidence. Overall, guidelines consistently advocate for trauma-focused psychological interventions as the primary treatment for PTSD.

Guidelines from NICE and the World Health Organization do not recommend medications as the primary treatment; the American Psychiatric Association and the US Department of Veterans Affairs support selective serotonin reuptake inhibitors and prazosin but advise against benzodiazepines. Inpatient care may be necessary for individuals who pose a danger to themselves or others, or for those with severe PTSD from childhood abuse, to aid in emotional regulation and treatment.

Jasvinder Chawla, MD, Professor of Neurology, Loyola University Medical Center, Maywood; Director, Clinical Neurophysiology Lab, Department of Neurology, Hines VA Hospital, Hines, IL.
Jasvinder Chawla, MD, has disclosed no relevant financial relationships.

Image Quizzes are fictional or fictionalized clinical scenarios intended to provide evidence-based educational takeaways.

The most likely diagnosis for this patient is veteran posttraumatic stress disorder (PTSD), given his history of combat exposure and symptoms, such as severe headaches, difficulty concentrating, mood swings, nightmares, flashbacks, increased startle response, and hypervigilance. MRI findings showing significant changes in the limbic system and hippocampal regions support this diagnosis. Other potential diagnoses, like traumatic brain injury, chronic migraine, and major depressive disorder, are less likely because of their inability to account for the full range of his symptoms and specific MRI abnormalities.

PTSD, experienced by a subset of individuals after exposure to life-threatening events, has a lifetime prevalence of 4%-7% and a current prevalence of 1%-3%, with higher rates in older women, those with more trauma, and combat veterans. Nearly half of US veterans are aged 65 or older, many being Vietnam-era veterans at elevated risk for PTSD. Prevalence rates in older veterans range between 1% and 22%.

PTSD is characterized by intrusive thoughts, flashbacks, nightmares, avoidance of reminders, hypervigilance, and sleep difficulties, significantly disrupting interpersonal and occupational functioning. Screening tools like the primary care (PC) PTSD-5 and PCL-5, used in primary care settings, are effective for early detection, provisional diagnosis, and monitoring of symptom changes. The clinician-administered PTSD scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition DSM-5 (CAPS-5) is the gold standard for diagnosis, particularly among veterans, with multimethod assessments combining self-report measures and semi-structured interviews recommended for accuracy. The DSM-5 criteria for PTSD diagnosis describe exposure to traumatic events, intrusion symptoms, avoidance behaviors, negative mood, and altered arousal, with symptoms persisting for over a month and causing significant distress or functional impairment. 

Research has identified consistent anatomical and functional changes in PTSD patients, such as smaller hippocampi, decreased corpus callosum and prefrontal cortex, increased amygdala reactivity, and decreased prefrontal cortex activity. PTSD, linked to alterations in brain regions involved in fear learning and memory, shows diminished structural integrity in executive function areas, reduced cortical volumes in the cingulate brain cortex and frontal regions, and reduced white matter integrity in key brain pathways. Neuroimaging findings, however, are primarily used for research currently and have yet to be widely implemented in clinical guidelines.

International PTSD treatment guidelines consistently recognize trauma-focused cognitive-behavioral therapies (CBTs), such as cognitive processing therapy (CPT), prolonged exposure (PE), and eye movement desensitization and reprocessing (EMDR) as the gold standard. Recent guidelines have expanded the list of recommended treatments: The 2023 Department of Veterans Affairs and Department of Defense guidelines in the United States also endorse therapies like written narrative exposure and brief eclectic therapy. Internationally, guidelines do not perfectly coincide, as the 2018 update from the United Kingdom's National Institute for Health and Care Excellence (NICE) gives the highest recommendations to PE and CPT but rates EMDR slightly lower for military veterans because of limited evidence. Overall, guidelines consistently advocate for trauma-focused psychological interventions as the primary treatment for PTSD.

Guidelines from NICE and the World Health Organization do not recommend medications as the primary treatment; the American Psychiatric Association and the US Department of Veterans Affairs support selective serotonin reuptake inhibitors and prazosin but advise against benzodiazepines. Inpatient care may be necessary for individuals who pose a danger to themselves or others, or for those with severe PTSD from childhood abuse, to aid in emotional regulation and treatment.

Jasvinder Chawla, MD, Professor of Neurology, Loyola University Medical Center, Maywood; Director, Clinical Neurophysiology Lab, Department of Neurology, Hines VA Hospital, Hines, IL.
Jasvinder Chawla, MD, has disclosed no relevant financial relationships.

Image Quizzes are fictional or fictionalized clinical scenarios intended to provide evidence-based educational takeaways.

The most likely diagnosis for this patient is veteran posttraumatic stress disorder (PTSD), given his history of combat exposure and symptoms, such as severe headaches, difficulty concentrating, mood swings, nightmares, flashbacks, increased startle response, and hypervigilance. MRI findings showing significant changes in the limbic system and hippocampal regions support this diagnosis. Other potential diagnoses, like traumatic brain injury, chronic migraine, and major depressive disorder, are less likely because of their inability to account for the full range of his symptoms and specific MRI abnormalities.

PTSD, experienced by a subset of individuals after exposure to life-threatening events, has a lifetime prevalence of 4%-7% and a current prevalence of 1%-3%, with higher rates in older women, those with more trauma, and combat veterans. Nearly half of US veterans are aged 65 or older, many being Vietnam-era veterans at elevated risk for PTSD. Prevalence rates in older veterans range between 1% and 22%.

PTSD is characterized by intrusive thoughts, flashbacks, nightmares, avoidance of reminders, hypervigilance, and sleep difficulties, significantly disrupting interpersonal and occupational functioning. Screening tools like the primary care (PC) PTSD-5 and PCL-5, used in primary care settings, are effective for early detection, provisional diagnosis, and monitoring of symptom changes. The clinician-administered PTSD scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition DSM-5 (CAPS-5) is the gold standard for diagnosis, particularly among veterans, with multimethod assessments combining self-report measures and semi-structured interviews recommended for accuracy. The DSM-5 criteria for PTSD diagnosis describe exposure to traumatic events, intrusion symptoms, avoidance behaviors, negative mood, and altered arousal, with symptoms persisting for over a month and causing significant distress or functional impairment. 

Research has identified consistent anatomical and functional changes in PTSD patients, such as smaller hippocampi, decreased corpus callosum and prefrontal cortex, increased amygdala reactivity, and decreased prefrontal cortex activity. PTSD, linked to alterations in brain regions involved in fear learning and memory, shows diminished structural integrity in executive function areas, reduced cortical volumes in the cingulate brain cortex and frontal regions, and reduced white matter integrity in key brain pathways. Neuroimaging findings, however, are primarily used for research currently and have yet to be widely implemented in clinical guidelines.

International PTSD treatment guidelines consistently recognize trauma-focused cognitive-behavioral therapies (CBTs), such as cognitive processing therapy (CPT), prolonged exposure (PE), and eye movement desensitization and reprocessing (EMDR) as the gold standard. Recent guidelines have expanded the list of recommended treatments: The 2023 Department of Veterans Affairs and Department of Defense guidelines in the United States also endorse therapies like written narrative exposure and brief eclectic therapy. Internationally, guidelines do not perfectly coincide, as the 2018 update from the United Kingdom's National Institute for Health and Care Excellence (NICE) gives the highest recommendations to PE and CPT but rates EMDR slightly lower for military veterans because of limited evidence. Overall, guidelines consistently advocate for trauma-focused psychological interventions as the primary treatment for PTSD.

Guidelines from NICE and the World Health Organization do not recommend medications as the primary treatment; the American Psychiatric Association and the US Department of Veterans Affairs support selective serotonin reuptake inhibitors and prazosin but advise against benzodiazepines. Inpatient care may be necessary for individuals who pose a danger to themselves or others, or for those with severe PTSD from childhood abuse, to aid in emotional regulation and treatment.

Jasvinder Chawla, MD, Professor of Neurology, Loyola University Medical Center, Maywood; Director, Clinical Neurophysiology Lab, Department of Neurology, Hines VA Hospital, Hines, IL.
Jasvinder Chawla, MD, has disclosed no relevant financial relationships.

Image Quizzes are fictional or fictionalized clinical scenarios intended to provide evidence-based educational takeaways.

Click to view more from Pulmonology Data Trends 2024. 

Click to view more from Pulmonology Data Trends 2024. 

Click to view more from Pulmonology Data Trends 2024. 

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

Editor's Note: This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.