Cutis

To the Editor:

Scrub typhus (ST) is an infection caused by Orientia tsutsugamushi (genus Rickettsia), which is transmitted by the larvae of trombiculid mites, commonly called chiggers. The disease mainly has been described in Asia in an area known as the Tsutsugamushi Triangle, delineated by Pakistan, eastern Russia, and northern Australia. Although this classic distribution remains, recent reports have documented 1 case in the Arabian Peninsula¹ and more than 16 cases in southern Chile.^2-4 The first case in Chile was published in 2011 from Chiloé Island.² To date, no other cases have been reported in the Americas.^1-6

We describe a new case of ST from Chiloé Island and compare it to the first case reported in Chile in 2011.² Both patients showed the typical clinical manifestation, but because ST has become an increasingly suspected disease in southern regions of Chile, new cases are now easily diagnosed. This infection is diagnosed mainly by skin lesions; therefore, dermatologists should be aware of this diagnosis when presented with a febrile rash.

A 67-year-old man from the city of Punta Arenas presented to the emergency department with a dark necrotic lesion on the right foot of 1 week’s duration. The patient later developed a generalized pruritic rash and fever. He also reported muscle pain, headache, cough, night sweats, and odynophagia. He reported recent travel to a rural area in the northern part of Chiloé Island, where he came into contact with firewood and participated in outdoor activities. He had no other relevant medical history.

Physical examination revealed a temperature of 38 °C and a macular rash, with some papules distributed mainly on the face, trunk, and proximal extremities (Figure 1). He had a necrotic eschar on the dorsum of the right foot, with an erythematous halo (tache noire)(Figure 2).

Scrub typhus is a high-impact disease in Asia, described mainly in an area known as the Tsutsugamushi Triangle. Recent reports show important epidemiologic changes in the distribution of the disease, with new published reports of cases outside this endemic area—1 in the Arabian peninsula¹ and more than 16 in southern Chile.^2-4

The disease begins with a painless, erythematous, and usually unnoticed papule at the site of the bite. After 48 to 72 hours, the papule changes to a necrotic form (tache noire), surrounded by a red halo that often is small, similar to a cigarette burn. This lesion is described in 20% to 90% of infected patients in different series.⁷ Two or 3 days later (1 to 3 weeks after exposure), high fever suddenly develops. Along with fever, a maculopapular rash distributed centrifugally develops, without compromise of the palms or soles. Patients frequently report headache and night sweating. Sometimes, ST is accompanied by muscle or joint pain, red eye, cough, and abdominal pain. Hearing loss and altered mental status less frequently have been reported.^5,8

Common laboratory tests can be of use in diagnosis. An elevated C-reactive protein level and a slight to moderate increase in hepatic transaminases should be expected. Thrombocytopenia, leukopenia, and elevation of the lactate dehydrogenase level less frequently are present.^5,9

Our case de1monstrated a typical presentation. The patient developed a febrile syndrome with a generalized rash and a tache noire–type eschar associated with muscle pain, headache, cough, night sweats, and odynophagia. Because of epidemiologic changes in the area, the familiar clinical findings, and laboratory confirmation, histologic studies were unnecessary. In cases in which the diagnosis is not evident, skin biopsy could be useful, as in the first case reported in Chile.²

In that first case, the patient initially was hospitalized because of a febrile syndrome; eventually, a necrotic eschar was noticed on his leg. He had been staying on Chiloé Island and reported being bitten by leeches on multiple occasions. Laboratory findings revealed only slightly raised levels of hepatic transaminases and alkaline phosphatase. After a more precise dermatologic evaluation, the eschar of a tache noire, combined with other clinical and laboratory findings, raised suspicion of ST. Because this entity had never been described in Chile, biopsy of the eschar was taken to consider other entities in the differential diagnosis. Biopsy showed necrotizing leukocytoclastic vasculitis in the dermis and subcutaneous tissue, perivascular inflammatory infiltrates comprising lymphocytes and macrophages, and rickettsial microorganisms inside endothelial cells under electron microscopic examination. The specimen was tested for the 16S ribosomal RNA Orientia gene; its presence confirmed the diagnosis.²

Classically, histology from the eschar shows signs of vasculitis and rickettsial microorganisms inside endothelial cells on electron microscopy.^2,10 More recent publications describe important necrotic changes within keratinocytes as well as an inflammatory infiltrate comprising antigen-presenting cells, monocytes, macrophages, and dendritic cells. Using high-resolution thin sections with confocal laser scanning microscopy and staining of specific monoclonal antibodies against 56 kDa type-specific surface antigens, the bacteria were found inside antigen-presenting cells, many of them located perivascularly or passing through the endothelium.¹¹

The causal agent in Asia is O tsutsugamushi, an obligate intracellular bacterium (genus Rickettsia). Orientia species are transmitted by larvae of trombiculid mites, commonly called chiggers. The reservoir is believed to be the same as with chiggers, in which some vertebrates become infected and trombiculid mites feed on them.¹² Recent studies of Chilean cases have revealed the presence of a novel Orientia species, Candidatus Orientia chiloensis and its vector, trombiculid mites from the Herpetacarus species, Quadraseta species, and Paratrombicula species genera.^13,14

A high seroprevalence of Orientia species in dogs was reported in the main cities of Chiloé Island. Rates were higher in rural settings and older dogs. Of 202 specimens, 21.3% were positive for IgG against Orientia species.¹⁵

In Chile, most cases of ST came from Chiloé Island; some reports of cases from continental Chilean regions have been published.⁶ Most cases have occurred in the context of activities that brought the patients in contact with plants and firewood in rural areas during the summer.^3-6

The diagnosis of ST is eminently clinical, based on the triad of fever, macular or papular rash, and an inoculation necrotic eschar. The diagnosis is supported by epidemiologic facts and fast recovery after treatment is initiated.¹⁶ Although the diagnosis can be established based on a quick recovery in endemic countries, in areas such as Chile where incidence and distribution are not completely known, it is better to confirm the diagnosis with laboratory tests without delaying treatment. Several testing options exist, including serologic techniques (immunofluorescence or enzyme-linked immunosorbent assay), culture, and detection of the genetic material of Orientia species by PCR. Usually, IgM titers initially are negative, and IgG testing requires paired samples (acute and convalescent) to demonstrate seroconversion and therefore acute infection.¹⁷ Because culture requires a highly specialized laboratory, it is not frequently used. Polymerase chain reaction is recognized as the best confirmation method due to its high sensitivity and because it remains positive for a few days after treatment has been initiated. The specimen of choice is the eschar because of its high bacterial load. The base of the scar and the buffy coat are useful specimens when the eschar is unavailable.^5,17-19

Due to potential complications of ST, empirical treatment with an antibiotic should be started based on clinical facts and never delayed because of diagnostic tests.¹⁸ Classically, ST is treated with a member of the tetracycline family, such as doxycycline, which provides a cure rate of 63% to 100% in ST.⁵

A 2017 systematic review of treatment options for this infection examined 11 studies from Southeast Asia, China, and South Korea (N=957).¹⁶ The review mainly compared doxycycline with azithromycin, chloramphenicol, and tetracycline. No significant difference in cure rate was noted in comparing doxycycline with any of the other 3 antibiotics; most of the studies examined were characterized by a moderate level of evidence. Regarding adverse effects, doxycycline showed a few more cases of gastrointestinal intolerance, and in 2 of 4 studies with chloramphenicol, patients presented with leukopenia.¹⁶ Several studies compared standard treatment (doxycycline) with rifampicin, telithromycin, erythromycin, and levofloxacin individually; similar cure rates were noted between doxycycline and each of those 4 agents.

Therapeutic failure in ST has been reported in several cases with the use of levofloxacin.²⁰ Evidence for this novel antibiotic is still insufficient. Further studies are needed before rifampicin, telithromycin, erythromycin, or levofloxacin can be considered as options.Scrub typhus usually resolves within a few weeks. Left untreated, the disease can cause complications such as pneumonia, meningoencephalitis, renal failure, and even multiorgan failure and death. Without treatment, mortality is variable. A 2015 systematic review of mortality from untreated ST showed, on average, mortality of 6% (range, 0%–70%).²¹ When ST is treated, mortality falls to 0% to 30%.²² Cases reported in Chile have neither been lethal nor presented with severe complications.^4,5

Scrub typhus is an infectious disease common in Asia, caused by O tsutsugamushi and transmitted by chiggers. It should be suspected when a febrile macular or papular rash and a tache noire appear. The diagnosis can be supported by laboratory findings, such as an elevated C-reactive protein level or a slight increase in the levels of hepatic transaminases, and response to treatment. The diagnosis is confirmed by serology or PCR of a specimen of the eschar. Empiric therapy with antibiotics is mandatory; doxycycline is the first option.

First described in Chile in 2011,² ST was seen in a patient in whom disease was suspected because of clinical characteristics, laboratory and histologic findings, absence of prior reporting in South America, and confirmation with PCR targeting the 16S ribosomal RNA Orientia gene from specimens of the eschar. By 2020, 60 cases have been confirmed in Chile, not all of them published; there are no other reported cases in South America.

When comparing the first case in Chile² with our case, we noted that both described classic clinical findings; however, the management approach and diagnostic challenges have evolved over time. Nowadays, ST is highly suspected, so it can be largely recognized and treated, which also provides better understanding of the nature of this disease in Chile. Because this infection is diagnosed mainly by characteristic cutaneous lesions, dermatologists should be aware of its epidemiology, clinical features, and transmission, and they should stay open to the possibility of this (until now) unusual diagnosis in South America.

Acknowledgments
The authors would like to thank the Chilean Rickettsia & Zoonosis Research Group (Thomas Weitzel, MD [Santiago, Chile]; Constanza Martínez-Valdebenito [Santiago, Chile]; and Gerardo Acosta-Jammet, DSc [Valdivia, Chile]), whose study in execution in the country allowed the detection of the case and confirmation by PCR. The authors also thank Juan Carlos Román, MD (Chiloé, Chile) who was part of the team that detected this case.

To the Editor:

Scrub typhus (ST) is an infection caused by Orientia tsutsugamushi (genus Rickettsia), which is transmitted by the larvae of trombiculid mites, commonly called chiggers. The disease mainly has been described in Asia in an area known as the Tsutsugamushi Triangle, delineated by Pakistan, eastern Russia, and northern Australia. Although this classic distribution remains, recent reports have documented 1 case in the Arabian Peninsula¹ and more than 16 cases in southern Chile.^2-4 The first case in Chile was published in 2011 from Chiloé Island.² To date, no other cases have been reported in the Americas.^1-6

We describe a new case of ST from Chiloé Island and compare it to the first case reported in Chile in 2011.² Both patients showed the typical clinical manifestation, but because ST has become an increasingly suspected disease in southern regions of Chile, new cases are now easily diagnosed. This infection is diagnosed mainly by skin lesions; therefore, dermatologists should be aware of this diagnosis when presented with a febrile rash.

A 67-year-old man from the city of Punta Arenas presented to the emergency department with a dark necrotic lesion on the right foot of 1 week’s duration. The patient later developed a generalized pruritic rash and fever. He also reported muscle pain, headache, cough, night sweats, and odynophagia. He reported recent travel to a rural area in the northern part of Chiloé Island, where he came into contact with firewood and participated in outdoor activities. He had no other relevant medical history.

Physical examination revealed a temperature of 38 °C and a macular rash, with some papules distributed mainly on the face, trunk, and proximal extremities (Figure 1). He had a necrotic eschar on the dorsum of the right foot, with an erythematous halo (tache noire)(Figure 2).

Scrub typhus is a high-impact disease in Asia, described mainly in an area known as the Tsutsugamushi Triangle. Recent reports show important epidemiologic changes in the distribution of the disease, with new published reports of cases outside this endemic area—1 in the Arabian peninsula¹ and more than 16 in southern Chile.^2-4

The disease begins with a painless, erythematous, and usually unnoticed papule at the site of the bite. After 48 to 72 hours, the papule changes to a necrotic form (tache noire), surrounded by a red halo that often is small, similar to a cigarette burn. This lesion is described in 20% to 90% of infected patients in different series.⁷ Two or 3 days later (1 to 3 weeks after exposure), high fever suddenly develops. Along with fever, a maculopapular rash distributed centrifugally develops, without compromise of the palms or soles. Patients frequently report headache and night sweating. Sometimes, ST is accompanied by muscle or joint pain, red eye, cough, and abdominal pain. Hearing loss and altered mental status less frequently have been reported.^5,8

Common laboratory tests can be of use in diagnosis. An elevated C-reactive protein level and a slight to moderate increase in hepatic transaminases should be expected. Thrombocytopenia, leukopenia, and elevation of the lactate dehydrogenase level less frequently are present.^5,9

Our case de1monstrated a typical presentation. The patient developed a febrile syndrome with a generalized rash and a tache noire–type eschar associated with muscle pain, headache, cough, night sweats, and odynophagia. Because of epidemiologic changes in the area, the familiar clinical findings, and laboratory confirmation, histologic studies were unnecessary. In cases in which the diagnosis is not evident, skin biopsy could be useful, as in the first case reported in Chile.²

In that first case, the patient initially was hospitalized because of a febrile syndrome; eventually, a necrotic eschar was noticed on his leg. He had been staying on Chiloé Island and reported being bitten by leeches on multiple occasions. Laboratory findings revealed only slightly raised levels of hepatic transaminases and alkaline phosphatase. After a more precise dermatologic evaluation, the eschar of a tache noire, combined with other clinical and laboratory findings, raised suspicion of ST. Because this entity had never been described in Chile, biopsy of the eschar was taken to consider other entities in the differential diagnosis. Biopsy showed necrotizing leukocytoclastic vasculitis in the dermis and subcutaneous tissue, perivascular inflammatory infiltrates comprising lymphocytes and macrophages, and rickettsial microorganisms inside endothelial cells under electron microscopic examination. The specimen was tested for the 16S ribosomal RNA Orientia gene; its presence confirmed the diagnosis.²

Classically, histology from the eschar shows signs of vasculitis and rickettsial microorganisms inside endothelial cells on electron microscopy.^2,10 More recent publications describe important necrotic changes within keratinocytes as well as an inflammatory infiltrate comprising antigen-presenting cells, monocytes, macrophages, and dendritic cells. Using high-resolution thin sections with confocal laser scanning microscopy and staining of specific monoclonal antibodies against 56 kDa type-specific surface antigens, the bacteria were found inside antigen-presenting cells, many of them located perivascularly or passing through the endothelium.¹¹

The causal agent in Asia is O tsutsugamushi, an obligate intracellular bacterium (genus Rickettsia). Orientia species are transmitted by larvae of trombiculid mites, commonly called chiggers. The reservoir is believed to be the same as with chiggers, in which some vertebrates become infected and trombiculid mites feed on them.¹² Recent studies of Chilean cases have revealed the presence of a novel Orientia species, Candidatus Orientia chiloensis and its vector, trombiculid mites from the Herpetacarus species, Quadraseta species, and Paratrombicula species genera.^13,14

A high seroprevalence of Orientia species in dogs was reported in the main cities of Chiloé Island. Rates were higher in rural settings and older dogs. Of 202 specimens, 21.3% were positive for IgG against Orientia species.¹⁵

In Chile, most cases of ST came from Chiloé Island; some reports of cases from continental Chilean regions have been published.⁶ Most cases have occurred in the context of activities that brought the patients in contact with plants and firewood in rural areas during the summer.^3-6

The diagnosis of ST is eminently clinical, based on the triad of fever, macular or papular rash, and an inoculation necrotic eschar. The diagnosis is supported by epidemiologic facts and fast recovery after treatment is initiated.¹⁶ Although the diagnosis can be established based on a quick recovery in endemic countries, in areas such as Chile where incidence and distribution are not completely known, it is better to confirm the diagnosis with laboratory tests without delaying treatment. Several testing options exist, including serologic techniques (immunofluorescence or enzyme-linked immunosorbent assay), culture, and detection of the genetic material of Orientia species by PCR. Usually, IgM titers initially are negative, and IgG testing requires paired samples (acute and convalescent) to demonstrate seroconversion and therefore acute infection.¹⁷ Because culture requires a highly specialized laboratory, it is not frequently used. Polymerase chain reaction is recognized as the best confirmation method due to its high sensitivity and because it remains positive for a few days after treatment has been initiated. The specimen of choice is the eschar because of its high bacterial load. The base of the scar and the buffy coat are useful specimens when the eschar is unavailable.^5,17-19

Due to potential complications of ST, empirical treatment with an antibiotic should be started based on clinical facts and never delayed because of diagnostic tests.¹⁸ Classically, ST is treated with a member of the tetracycline family, such as doxycycline, which provides a cure rate of 63% to 100% in ST.⁵

A 2017 systematic review of treatment options for this infection examined 11 studies from Southeast Asia, China, and South Korea (N=957).¹⁶ The review mainly compared doxycycline with azithromycin, chloramphenicol, and tetracycline. No significant difference in cure rate was noted in comparing doxycycline with any of the other 3 antibiotics; most of the studies examined were characterized by a moderate level of evidence. Regarding adverse effects, doxycycline showed a few more cases of gastrointestinal intolerance, and in 2 of 4 studies with chloramphenicol, patients presented with leukopenia.¹⁶ Several studies compared standard treatment (doxycycline) with rifampicin, telithromycin, erythromycin, and levofloxacin individually; similar cure rates were noted between doxycycline and each of those 4 agents.

Therapeutic failure in ST has been reported in several cases with the use of levofloxacin.²⁰ Evidence for this novel antibiotic is still insufficient. Further studies are needed before rifampicin, telithromycin, erythromycin, or levofloxacin can be considered as options.Scrub typhus usually resolves within a few weeks. Left untreated, the disease can cause complications such as pneumonia, meningoencephalitis, renal failure, and even multiorgan failure and death. Without treatment, mortality is variable. A 2015 systematic review of mortality from untreated ST showed, on average, mortality of 6% (range, 0%–70%).²¹ When ST is treated, mortality falls to 0% to 30%.²² Cases reported in Chile have neither been lethal nor presented with severe complications.^4,5

Scrub typhus is an infectious disease common in Asia, caused by O tsutsugamushi and transmitted by chiggers. It should be suspected when a febrile macular or papular rash and a tache noire appear. The diagnosis can be supported by laboratory findings, such as an elevated C-reactive protein level or a slight increase in the levels of hepatic transaminases, and response to treatment. The diagnosis is confirmed by serology or PCR of a specimen of the eschar. Empiric therapy with antibiotics is mandatory; doxycycline is the first option.

First described in Chile in 2011,² ST was seen in a patient in whom disease was suspected because of clinical characteristics, laboratory and histologic findings, absence of prior reporting in South America, and confirmation with PCR targeting the 16S ribosomal RNA Orientia gene from specimens of the eschar. By 2020, 60 cases have been confirmed in Chile, not all of them published; there are no other reported cases in South America.

When comparing the first case in Chile² with our case, we noted that both described classic clinical findings; however, the management approach and diagnostic challenges have evolved over time. Nowadays, ST is highly suspected, so it can be largely recognized and treated, which also provides better understanding of the nature of this disease in Chile. Because this infection is diagnosed mainly by characteristic cutaneous lesions, dermatologists should be aware of its epidemiology, clinical features, and transmission, and they should stay open to the possibility of this (until now) unusual diagnosis in South America.

Acknowledgments
The authors would like to thank the Chilean Rickettsia & Zoonosis Research Group (Thomas Weitzel, MD [Santiago, Chile]; Constanza Martínez-Valdebenito [Santiago, Chile]; and Gerardo Acosta-Jammet, DSc [Valdivia, Chile]), whose study in execution in the country allowed the detection of the case and confirmation by PCR. The authors also thank Juan Carlos Román, MD (Chiloé, Chile) who was part of the team that detected this case.

To the Editor:

Scrub typhus (ST) is an infection caused by Orientia tsutsugamushi (genus Rickettsia), which is transmitted by the larvae of trombiculid mites, commonly called chiggers. The disease mainly has been described in Asia in an area known as the Tsutsugamushi Triangle, delineated by Pakistan, eastern Russia, and northern Australia. Although this classic distribution remains, recent reports have documented 1 case in the Arabian Peninsula¹ and more than 16 cases in southern Chile.^2-4 The first case in Chile was published in 2011 from Chiloé Island.² To date, no other cases have been reported in the Americas.^1-6

We describe a new case of ST from Chiloé Island and compare it to the first case reported in Chile in 2011.² Both patients showed the typical clinical manifestation, but because ST has become an increasingly suspected disease in southern regions of Chile, new cases are now easily diagnosed. This infection is diagnosed mainly by skin lesions; therefore, dermatologists should be aware of this diagnosis when presented with a febrile rash.

A 67-year-old man from the city of Punta Arenas presented to the emergency department with a dark necrotic lesion on the right foot of 1 week’s duration. The patient later developed a generalized pruritic rash and fever. He also reported muscle pain, headache, cough, night sweats, and odynophagia. He reported recent travel to a rural area in the northern part of Chiloé Island, where he came into contact with firewood and participated in outdoor activities. He had no other relevant medical history.

Physical examination revealed a temperature of 38 °C and a macular rash, with some papules distributed mainly on the face, trunk, and proximal extremities (Figure 1). He had a necrotic eschar on the dorsum of the right foot, with an erythematous halo (tache noire)(Figure 2).

Scrub typhus is a high-impact disease in Asia, described mainly in an area known as the Tsutsugamushi Triangle. Recent reports show important epidemiologic changes in the distribution of the disease, with new published reports of cases outside this endemic area—1 in the Arabian peninsula¹ and more than 16 in southern Chile.^2-4

The disease begins with a painless, erythematous, and usually unnoticed papule at the site of the bite. After 48 to 72 hours, the papule changes to a necrotic form (tache noire), surrounded by a red halo that often is small, similar to a cigarette burn. This lesion is described in 20% to 90% of infected patients in different series.⁷ Two or 3 days later (1 to 3 weeks after exposure), high fever suddenly develops. Along with fever, a maculopapular rash distributed centrifugally develops, without compromise of the palms or soles. Patients frequently report headache and night sweating. Sometimes, ST is accompanied by muscle or joint pain, red eye, cough, and abdominal pain. Hearing loss and altered mental status less frequently have been reported.^5,8

Common laboratory tests can be of use in diagnosis. An elevated C-reactive protein level and a slight to moderate increase in hepatic transaminases should be expected. Thrombocytopenia, leukopenia, and elevation of the lactate dehydrogenase level less frequently are present.^5,9

Our case de1monstrated a typical presentation. The patient developed a febrile syndrome with a generalized rash and a tache noire–type eschar associated with muscle pain, headache, cough, night sweats, and odynophagia. Because of epidemiologic changes in the area, the familiar clinical findings, and laboratory confirmation, histologic studies were unnecessary. In cases in which the diagnosis is not evident, skin biopsy could be useful, as in the first case reported in Chile.²

In that first case, the patient initially was hospitalized because of a febrile syndrome; eventually, a necrotic eschar was noticed on his leg. He had been staying on Chiloé Island and reported being bitten by leeches on multiple occasions. Laboratory findings revealed only slightly raised levels of hepatic transaminases and alkaline phosphatase. After a more precise dermatologic evaluation, the eschar of a tache noire, combined with other clinical and laboratory findings, raised suspicion of ST. Because this entity had never been described in Chile, biopsy of the eschar was taken to consider other entities in the differential diagnosis. Biopsy showed necrotizing leukocytoclastic vasculitis in the dermis and subcutaneous tissue, perivascular inflammatory infiltrates comprising lymphocytes and macrophages, and rickettsial microorganisms inside endothelial cells under electron microscopic examination. The specimen was tested for the 16S ribosomal RNA Orientia gene; its presence confirmed the diagnosis.²

Classically, histology from the eschar shows signs of vasculitis and rickettsial microorganisms inside endothelial cells on electron microscopy.^2,10 More recent publications describe important necrotic changes within keratinocytes as well as an inflammatory infiltrate comprising antigen-presenting cells, monocytes, macrophages, and dendritic cells. Using high-resolution thin sections with confocal laser scanning microscopy and staining of specific monoclonal antibodies against 56 kDa type-specific surface antigens, the bacteria were found inside antigen-presenting cells, many of them located perivascularly or passing through the endothelium.¹¹

The causal agent in Asia is O tsutsugamushi, an obligate intracellular bacterium (genus Rickettsia). Orientia species are transmitted by larvae of trombiculid mites, commonly called chiggers. The reservoir is believed to be the same as with chiggers, in which some vertebrates become infected and trombiculid mites feed on them.¹² Recent studies of Chilean cases have revealed the presence of a novel Orientia species, Candidatus Orientia chiloensis and its vector, trombiculid mites from the Herpetacarus species, Quadraseta species, and Paratrombicula species genera.^13,14

A high seroprevalence of Orientia species in dogs was reported in the main cities of Chiloé Island. Rates were higher in rural settings and older dogs. Of 202 specimens, 21.3% were positive for IgG against Orientia species.¹⁵

In Chile, most cases of ST came from Chiloé Island; some reports of cases from continental Chilean regions have been published.⁶ Most cases have occurred in the context of activities that brought the patients in contact with plants and firewood in rural areas during the summer.^3-6

The diagnosis of ST is eminently clinical, based on the triad of fever, macular or papular rash, and an inoculation necrotic eschar. The diagnosis is supported by epidemiologic facts and fast recovery after treatment is initiated.¹⁶ Although the diagnosis can be established based on a quick recovery in endemic countries, in areas such as Chile where incidence and distribution are not completely known, it is better to confirm the diagnosis with laboratory tests without delaying treatment. Several testing options exist, including serologic techniques (immunofluorescence or enzyme-linked immunosorbent assay), culture, and detection of the genetic material of Orientia species by PCR. Usually, IgM titers initially are negative, and IgG testing requires paired samples (acute and convalescent) to demonstrate seroconversion and therefore acute infection.¹⁷ Because culture requires a highly specialized laboratory, it is not frequently used. Polymerase chain reaction is recognized as the best confirmation method due to its high sensitivity and because it remains positive for a few days after treatment has been initiated. The specimen of choice is the eschar because of its high bacterial load. The base of the scar and the buffy coat are useful specimens when the eschar is unavailable.^5,17-19

Due to potential complications of ST, empirical treatment with an antibiotic should be started based on clinical facts and never delayed because of diagnostic tests.¹⁸ Classically, ST is treated with a member of the tetracycline family, such as doxycycline, which provides a cure rate of 63% to 100% in ST.⁵

A 2017 systematic review of treatment options for this infection examined 11 studies from Southeast Asia, China, and South Korea (N=957).¹⁶ The review mainly compared doxycycline with azithromycin, chloramphenicol, and tetracycline. No significant difference in cure rate was noted in comparing doxycycline with any of the other 3 antibiotics; most of the studies examined were characterized by a moderate level of evidence. Regarding adverse effects, doxycycline showed a few more cases of gastrointestinal intolerance, and in 2 of 4 studies with chloramphenicol, patients presented with leukopenia.¹⁶ Several studies compared standard treatment (doxycycline) with rifampicin, telithromycin, erythromycin, and levofloxacin individually; similar cure rates were noted between doxycycline and each of those 4 agents.

Therapeutic failure in ST has been reported in several cases with the use of levofloxacin.²⁰ Evidence for this novel antibiotic is still insufficient. Further studies are needed before rifampicin, telithromycin, erythromycin, or levofloxacin can be considered as options.Scrub typhus usually resolves within a few weeks. Left untreated, the disease can cause complications such as pneumonia, meningoencephalitis, renal failure, and even multiorgan failure and death. Without treatment, mortality is variable. A 2015 systematic review of mortality from untreated ST showed, on average, mortality of 6% (range, 0%–70%).²¹ When ST is treated, mortality falls to 0% to 30%.²² Cases reported in Chile have neither been lethal nor presented with severe complications.^4,5

Scrub typhus is an infectious disease common in Asia, caused by O tsutsugamushi and transmitted by chiggers. It should be suspected when a febrile macular or papular rash and a tache noire appear. The diagnosis can be supported by laboratory findings, such as an elevated C-reactive protein level or a slight increase in the levels of hepatic transaminases, and response to treatment. The diagnosis is confirmed by serology or PCR of a specimen of the eschar. Empiric therapy with antibiotics is mandatory; doxycycline is the first option.

First described in Chile in 2011,² ST was seen in a patient in whom disease was suspected because of clinical characteristics, laboratory and histologic findings, absence of prior reporting in South America, and confirmation with PCR targeting the 16S ribosomal RNA Orientia gene from specimens of the eschar. By 2020, 60 cases have been confirmed in Chile, not all of them published; there are no other reported cases in South America.

When comparing the first case in Chile² with our case, we noted that both described classic clinical findings; however, the management approach and diagnostic challenges have evolved over time. Nowadays, ST is highly suspected, so it can be largely recognized and treated, which also provides better understanding of the nature of this disease in Chile. Because this infection is diagnosed mainly by characteristic cutaneous lesions, dermatologists should be aware of its epidemiology, clinical features, and transmission, and they should stay open to the possibility of this (until now) unusual diagnosis in South America.

Acknowledgments
The authors would like to thank the Chilean Rickettsia & Zoonosis Research Group (Thomas Weitzel, MD [Santiago, Chile]; Constanza Martínez-Valdebenito [Santiago, Chile]; and Gerardo Acosta-Jammet, DSc [Valdivia, Chile]), whose study in execution in the country allowed the detection of the case and confirmation by PCR. The authors also thank Juan Carlos Román, MD (Chiloé, Chile) who was part of the team that detected this case.

Practice Gap

Basal cell carcinoma (BCC) is the most common cancer, and its incidence is on the rise.¹ The risk of this skin cancer is increased when there is a history of squamous cell carcinoma (SCC) or BCC.² Basal cell carcinoma often is found in sun-exposed areas, most commonly due to a history of intense sunburn.³ Other risk factors include male gender and increased age.⁴

Eighty percent to 85% of BCCs present on the head and neck⁵; however, BCC also can occur in unusual locations. When BCC presents in areas such as the perianal region, it is found to be larger than when found in more common areas,⁶ likely because neoplasms in this sensitive area often are overlooked. Literature on BCC of the intergluteal crease is limited.⁷ Being educated on the existence of BCC in this sensitive area can aid proper diagnosis.

The Technique and Case

An 83-year-old woman presented to the dermatology clinic for a suspicious lesion in the intergluteal crease that was tender to palpation with drainage. She first noticed this lesion and reported it to her primary care physician at a visit 6 months prior. The primary care physician did not pursue investigation of the lesion. One month later, the patient was seen by a gastroenterologist for the lesion and was referred to dermatology. The patient’s medical history included SCC and BCC on the face, both treated successfully with Mohs micrographic surgery.

Physical examination revealed a 2.6×1.1-cm, erythematous, nodular plaque in the coccygeal area of the intergluteal crease (Figure 1). A shave biopsy disclosed BCC, nodular type, ulcerated. Microscopically, there were nodular aggregates of basaloid cells with hyperchromatic nuclei and peripheral palisading, separated from mucinous stromal surroundings by artefactual clefts.

Practical Implications

Without thorough examination, this cancerous lesion would not have been seen (Figure 2). Therefore, it is important to practice thorough physical examination skills to avoid missing these cancers, particularly when examining a patient with a history of SCC or BCC. Furthermore, biopsy is recommended for suspicious lesions to rule out BCC.

Be careful not to get caught up in epidemiological or demographic considerations when making a diagnosis of this kind or when assessing the severity of a lesion. This patient, for instance, was female, which makes her less likely to present with BCC.⁸ Moreover, the cancer presented in a highly unlikely location for BCC, where there had not been significant sunburn.⁹ Patients and physicians should be educated about the incidence of BCC in unexpected areas; without a second and close look, this BCC could have been missed.

Final Thoughts

The literature continuously demonstrates the rarity of BCC in the intergluteal crease.¹⁰ However, when perianal BCC is properly identified and treated with local excision, prognosis is good.¹¹ Basal cell carcinoma has been seen to arise in other sensitive locations; vulvar, nipple, and scrotal BCC neoplasms are among the uncommon locations where BCC has appeared.¹² These areas are frequently—and easily—ignored. A total-body skin examination should be performed to ensure that these insidious-onset carcinomas are not overlooked to protect patients from the adverse consequences of untreated cancer.¹³

Practice Gap

Basal cell carcinoma (BCC) is the most common cancer, and its incidence is on the rise.¹ The risk of this skin cancer is increased when there is a history of squamous cell carcinoma (SCC) or BCC.² Basal cell carcinoma often is found in sun-exposed areas, most commonly due to a history of intense sunburn.³ Other risk factors include male gender and increased age.⁴

Eighty percent to 85% of BCCs present on the head and neck⁵; however, BCC also can occur in unusual locations. When BCC presents in areas such as the perianal region, it is found to be larger than when found in more common areas,⁶ likely because neoplasms in this sensitive area often are overlooked. Literature on BCC of the intergluteal crease is limited.⁷ Being educated on the existence of BCC in this sensitive area can aid proper diagnosis.

The Technique and Case

An 83-year-old woman presented to the dermatology clinic for a suspicious lesion in the intergluteal crease that was tender to palpation with drainage. She first noticed this lesion and reported it to her primary care physician at a visit 6 months prior. The primary care physician did not pursue investigation of the lesion. One month later, the patient was seen by a gastroenterologist for the lesion and was referred to dermatology. The patient’s medical history included SCC and BCC on the face, both treated successfully with Mohs micrographic surgery.

Physical examination revealed a 2.6×1.1-cm, erythematous, nodular plaque in the coccygeal area of the intergluteal crease (Figure 1). A shave biopsy disclosed BCC, nodular type, ulcerated. Microscopically, there were nodular aggregates of basaloid cells with hyperchromatic nuclei and peripheral palisading, separated from mucinous stromal surroundings by artefactual clefts.

Practical Implications

Without thorough examination, this cancerous lesion would not have been seen (Figure 2). Therefore, it is important to practice thorough physical examination skills to avoid missing these cancers, particularly when examining a patient with a history of SCC or BCC. Furthermore, biopsy is recommended for suspicious lesions to rule out BCC.

Be careful not to get caught up in epidemiological or demographic considerations when making a diagnosis of this kind or when assessing the severity of a lesion. This patient, for instance, was female, which makes her less likely to present with BCC.⁸ Moreover, the cancer presented in a highly unlikely location for BCC, where there had not been significant sunburn.⁹ Patients and physicians should be educated about the incidence of BCC in unexpected areas; without a second and close look, this BCC could have been missed.

Final Thoughts

The literature continuously demonstrates the rarity of BCC in the intergluteal crease.¹⁰ However, when perianal BCC is properly identified and treated with local excision, prognosis is good.¹¹ Basal cell carcinoma has been seen to arise in other sensitive locations; vulvar, nipple, and scrotal BCC neoplasms are among the uncommon locations where BCC has appeared.¹² These areas are frequently—and easily—ignored. A total-body skin examination should be performed to ensure that these insidious-onset carcinomas are not overlooked to protect patients from the adverse consequences of untreated cancer.¹³

Practice Gap

Basal cell carcinoma (BCC) is the most common cancer, and its incidence is on the rise.¹ The risk of this skin cancer is increased when there is a history of squamous cell carcinoma (SCC) or BCC.² Basal cell carcinoma often is found in sun-exposed areas, most commonly due to a history of intense sunburn.³ Other risk factors include male gender and increased age.⁴

Eighty percent to 85% of BCCs present on the head and neck⁵; however, BCC also can occur in unusual locations. When BCC presents in areas such as the perianal region, it is found to be larger than when found in more common areas,⁶ likely because neoplasms in this sensitive area often are overlooked. Literature on BCC of the intergluteal crease is limited.⁷ Being educated on the existence of BCC in this sensitive area can aid proper diagnosis.

The Technique and Case

An 83-year-old woman presented to the dermatology clinic for a suspicious lesion in the intergluteal crease that was tender to palpation with drainage. She first noticed this lesion and reported it to her primary care physician at a visit 6 months prior. The primary care physician did not pursue investigation of the lesion. One month later, the patient was seen by a gastroenterologist for the lesion and was referred to dermatology. The patient’s medical history included SCC and BCC on the face, both treated successfully with Mohs micrographic surgery.

Physical examination revealed a 2.6×1.1-cm, erythematous, nodular plaque in the coccygeal area of the intergluteal crease (Figure 1). A shave biopsy disclosed BCC, nodular type, ulcerated. Microscopically, there were nodular aggregates of basaloid cells with hyperchromatic nuclei and peripheral palisading, separated from mucinous stromal surroundings by artefactual clefts.

Practical Implications

Without thorough examination, this cancerous lesion would not have been seen (Figure 2). Therefore, it is important to practice thorough physical examination skills to avoid missing these cancers, particularly when examining a patient with a history of SCC or BCC. Furthermore, biopsy is recommended for suspicious lesions to rule out BCC.

Be careful not to get caught up in epidemiological or demographic considerations when making a diagnosis of this kind or when assessing the severity of a lesion. This patient, for instance, was female, which makes her less likely to present with BCC.⁸ Moreover, the cancer presented in a highly unlikely location for BCC, where there had not been significant sunburn.⁹ Patients and physicians should be educated about the incidence of BCC in unexpected areas; without a second and close look, this BCC could have been missed.

Final Thoughts

The literature continuously demonstrates the rarity of BCC in the intergluteal crease.¹⁰ However, when perianal BCC is properly identified and treated with local excision, prognosis is good.¹¹ Basal cell carcinoma has been seen to arise in other sensitive locations; vulvar, nipple, and scrotal BCC neoplasms are among the uncommon locations where BCC has appeared.¹² These areas are frequently—and easily—ignored. A total-body skin examination should be performed to ensure that these insidious-onset carcinomas are not overlooked to protect patients from the adverse consequences of untreated cancer.¹³

The Diagnosis: Targetoid Hemosiderotic Hemangioma 

Targetoid hemosiderotic hemangioma (THH), also known as hobnail hemangioma, is a benign vascular tumor that usually occurs in young or middle-aged adults. It most commonly presents on the extremities or trunk as an isolated red-brown plaque or papule.^1,2 Histologically, THH is characterized by superficial dilated ectatic vessels with underlying proliferating vascular channels lined by plump hobnail endothelial cells.¹ Targetoid hemosiderotic hemangioma typically involves the dermis and spares the subcutis. The vascular channels may contain erythrocytes as well as pale eosinophilic lymph, as seen in our patient (quiz image). The deeper dermis contains vascular spaces that are more angulated and smaller and appear to be dissecting through the collagen bundles or collapsed.^1,3 A variable amount of hemosiderin deposition and extravasated erythrocytes are seen.^2,3 Histologic features evolve with the age of the lesion. Increasing amounts of hemosiderin deposition and erythrocyte extravasation may correspond histologically to the recent clinical color change reported by the patient.  

Verrucous hemangioma is a rare congenital vascular abnormality that is characterized by dilated vessels in the papillary dermis along with acanthosis, hyperkeratosis, and irregular papillomatosis, as seen in angiokeratoma.⁴ However, the vascular proliferation composed of variably sized, thin-walled capillaries extends into the deep dermis as well as the subcutis (Figure 1). Verrucous hemangioma most commonly is reported on the legs and generally starts as a violaceous patch that progresses into a hyperkeratotic verrucous plaque or nodule.^5,6  

Angiokeratoma is characterized by superficial vascular ectasia of the papillary dermis in association with overlying acanthosis, hyperkeratosis, and rete elongation.⁷ The dilated vascular spaces appear encircled by the epidermis (Figure 2). Intravascular thrombosis can be seen within the ectatic vessels.⁷ In contrast to verrucous hemangioma, angiokeratoma is limited to the papillary dermis. Therefore, obtaining a biopsy of sufficient depth is necessary for differentiation.⁸ There are 5 clinical presentations of angiokeratoma: sporadic, angiokeratoma of Mibelli, angiokeratoma of Fordyce, angiokeratoma circumscriptum, and angiokeratoma corporis diffusum (Fabry disease). Angiokeratomas may present on the lower extremities, tongue, trunk, and scrotum as hyperkeratotic, dark red to purple or black papules.⁷ 

There are 3 clinical stages of Kaposi sarcoma: patch, plaque, and nodular stages. The patch stage is characterized histologically by vascular channels that dissect through the dermis and extend around native vessels (the promontory sign)(Figure 3).^9,10 These features can show histologic overlap with THH. The plaque stage shows a more diffuse dermal vascular proliferation, increased cellularity of spindle cells, and possible extension into the subcutis.^9,10 Focal plasma cells, hemosiderin, and extravasated red blood cells can be seen. The nodular stage is characterized by a proliferation of spindle cells with red blood cells squeezed between slitlike vascular spaces, hyaline globules, and scattered mitotic figures, but not atypical forms.¹⁰ In this stage, plasma cells and hemosiderin are more readily identifiable. A biopsy from the nodular stage is unlikely to enter the histologic differential diagnosis with THH. Clinically, there are 4 variants of Kaposi sarcoma: the classic or sporadic form, an endemic form, iatrogenic, and AIDS associated. Overall, it is more common in males and can occur at any age.¹⁰ Human herpesvirus 8 is seen in all forms, and infected cells can be highlighted by the immunohistochemical stain for latent nuclear antigen 1.^9,10 

Angiosarcoma is a malignant endothelial tumor of soft tissue, skin, bone, and visceral organs.^11,12 Clinically, cutaneous angiosarcoma can present in a variety of ways, including single or multiple bluish red lesions that can ulcerate or bleed; violaceous nodules or plaques; and hematomalike lesions that can mimic epithelial neoplasms including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.^11,13,14 The cutaneous lesions most commonly occur on sun-exposed skin, particularly on the face and scalp.¹² Other clinical variants that are important to recognize are postradiation angiosarcoma, characterized by MYC gene amplification, and lymphedema-associated angiosarcoma (Stewart-Treves syndrome). Angiosarcoma can have a variety of morphologic features, ranging from well to poorly differentiated. Classically, angiosarcoma is characterized by infiltrating vascular spaces lined by atypical endothelial cells (Figure 4). Poorly differentiated angiosarcoma can demonstrate spindle, epithelioid, or polygonal cells with increased mitotic activity, pleomorphism, and irregular vascular spaces.¹¹ Endothelial markers such as ERG (erythroblast transformation specific-related gene)(nuclear) and CD31 (membranous) can be used to aid in the diagnosis of a poorly differentiated lesion. Epithelioid angiosarcoma also occasionally stains with cytokeratins.^13,14  

The Diagnosis: Targetoid Hemosiderotic Hemangioma 

Targetoid hemosiderotic hemangioma (THH), also known as hobnail hemangioma, is a benign vascular tumor that usually occurs in young or middle-aged adults. It most commonly presents on the extremities or trunk as an isolated red-brown plaque or papule.^1,2 Histologically, THH is characterized by superficial dilated ectatic vessels with underlying proliferating vascular channels lined by plump hobnail endothelial cells.¹ Targetoid hemosiderotic hemangioma typically involves the dermis and spares the subcutis. The vascular channels may contain erythrocytes as well as pale eosinophilic lymph, as seen in our patient (quiz image). The deeper dermis contains vascular spaces that are more angulated and smaller and appear to be dissecting through the collagen bundles or collapsed.^1,3 A variable amount of hemosiderin deposition and extravasated erythrocytes are seen.^2,3 Histologic features evolve with the age of the lesion. Increasing amounts of hemosiderin deposition and erythrocyte extravasation may correspond histologically to the recent clinical color change reported by the patient.  

Verrucous hemangioma is a rare congenital vascular abnormality that is characterized by dilated vessels in the papillary dermis along with acanthosis, hyperkeratosis, and irregular papillomatosis, as seen in angiokeratoma.⁴ However, the vascular proliferation composed of variably sized, thin-walled capillaries extends into the deep dermis as well as the subcutis (Figure 1). Verrucous hemangioma most commonly is reported on the legs and generally starts as a violaceous patch that progresses into a hyperkeratotic verrucous plaque or nodule.^5,6  

Angiokeratoma is characterized by superficial vascular ectasia of the papillary dermis in association with overlying acanthosis, hyperkeratosis, and rete elongation.⁷ The dilated vascular spaces appear encircled by the epidermis (Figure 2). Intravascular thrombosis can be seen within the ectatic vessels.⁷ In contrast to verrucous hemangioma, angiokeratoma is limited to the papillary dermis. Therefore, obtaining a biopsy of sufficient depth is necessary for differentiation.⁸ There are 5 clinical presentations of angiokeratoma: sporadic, angiokeratoma of Mibelli, angiokeratoma of Fordyce, angiokeratoma circumscriptum, and angiokeratoma corporis diffusum (Fabry disease). Angiokeratomas may present on the lower extremities, tongue, trunk, and scrotum as hyperkeratotic, dark red to purple or black papules.⁷ 

There are 3 clinical stages of Kaposi sarcoma: patch, plaque, and nodular stages. The patch stage is characterized histologically by vascular channels that dissect through the dermis and extend around native vessels (the promontory sign)(Figure 3).^9,10 These features can show histologic overlap with THH. The plaque stage shows a more diffuse dermal vascular proliferation, increased cellularity of spindle cells, and possible extension into the subcutis.^9,10 Focal plasma cells, hemosiderin, and extravasated red blood cells can be seen. The nodular stage is characterized by a proliferation of spindle cells with red blood cells squeezed between slitlike vascular spaces, hyaline globules, and scattered mitotic figures, but not atypical forms.¹⁰ In this stage, plasma cells and hemosiderin are more readily identifiable. A biopsy from the nodular stage is unlikely to enter the histologic differential diagnosis with THH. Clinically, there are 4 variants of Kaposi sarcoma: the classic or sporadic form, an endemic form, iatrogenic, and AIDS associated. Overall, it is more common in males and can occur at any age.¹⁰ Human herpesvirus 8 is seen in all forms, and infected cells can be highlighted by the immunohistochemical stain for latent nuclear antigen 1.^9,10 

Angiosarcoma is a malignant endothelial tumor of soft tissue, skin, bone, and visceral organs.^11,12 Clinically, cutaneous angiosarcoma can present in a variety of ways, including single or multiple bluish red lesions that can ulcerate or bleed; violaceous nodules or plaques; and hematomalike lesions that can mimic epithelial neoplasms including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.^11,13,14 The cutaneous lesions most commonly occur on sun-exposed skin, particularly on the face and scalp.¹² Other clinical variants that are important to recognize are postradiation angiosarcoma, characterized by MYC gene amplification, and lymphedema-associated angiosarcoma (Stewart-Treves syndrome). Angiosarcoma can have a variety of morphologic features, ranging from well to poorly differentiated. Classically, angiosarcoma is characterized by infiltrating vascular spaces lined by atypical endothelial cells (Figure 4). Poorly differentiated angiosarcoma can demonstrate spindle, epithelioid, or polygonal cells with increased mitotic activity, pleomorphism, and irregular vascular spaces.¹¹ Endothelial markers such as ERG (erythroblast transformation specific-related gene)(nuclear) and CD31 (membranous) can be used to aid in the diagnosis of a poorly differentiated lesion. Epithelioid angiosarcoma also occasionally stains with cytokeratins.^13,14  

The Diagnosis: Targetoid Hemosiderotic Hemangioma 

Targetoid hemosiderotic hemangioma (THH), also known as hobnail hemangioma, is a benign vascular tumor that usually occurs in young or middle-aged adults. It most commonly presents on the extremities or trunk as an isolated red-brown plaque or papule.^1,2 Histologically, THH is characterized by superficial dilated ectatic vessels with underlying proliferating vascular channels lined by plump hobnail endothelial cells.¹ Targetoid hemosiderotic hemangioma typically involves the dermis and spares the subcutis. The vascular channels may contain erythrocytes as well as pale eosinophilic lymph, as seen in our patient (quiz image). The deeper dermis contains vascular spaces that are more angulated and smaller and appear to be dissecting through the collagen bundles or collapsed.^1,3 A variable amount of hemosiderin deposition and extravasated erythrocytes are seen.^2,3 Histologic features evolve with the age of the lesion. Increasing amounts of hemosiderin deposition and erythrocyte extravasation may correspond histologically to the recent clinical color change reported by the patient.  

Verrucous hemangioma is a rare congenital vascular abnormality that is characterized by dilated vessels in the papillary dermis along with acanthosis, hyperkeratosis, and irregular papillomatosis, as seen in angiokeratoma.⁴ However, the vascular proliferation composed of variably sized, thin-walled capillaries extends into the deep dermis as well as the subcutis (Figure 1). Verrucous hemangioma most commonly is reported on the legs and generally starts as a violaceous patch that progresses into a hyperkeratotic verrucous plaque or nodule.^5,6  

Angiokeratoma is characterized by superficial vascular ectasia of the papillary dermis in association with overlying acanthosis, hyperkeratosis, and rete elongation.⁷ The dilated vascular spaces appear encircled by the epidermis (Figure 2). Intravascular thrombosis can be seen within the ectatic vessels.⁷ In contrast to verrucous hemangioma, angiokeratoma is limited to the papillary dermis. Therefore, obtaining a biopsy of sufficient depth is necessary for differentiation.⁸ There are 5 clinical presentations of angiokeratoma: sporadic, angiokeratoma of Mibelli, angiokeratoma of Fordyce, angiokeratoma circumscriptum, and angiokeratoma corporis diffusum (Fabry disease). Angiokeratomas may present on the lower extremities, tongue, trunk, and scrotum as hyperkeratotic, dark red to purple or black papules.⁷ 

There are 3 clinical stages of Kaposi sarcoma: patch, plaque, and nodular stages. The patch stage is characterized histologically by vascular channels that dissect through the dermis and extend around native vessels (the promontory sign)(Figure 3).^9,10 These features can show histologic overlap with THH. The plaque stage shows a more diffuse dermal vascular proliferation, increased cellularity of spindle cells, and possible extension into the subcutis.^9,10 Focal plasma cells, hemosiderin, and extravasated red blood cells can be seen. The nodular stage is characterized by a proliferation of spindle cells with red blood cells squeezed between slitlike vascular spaces, hyaline globules, and scattered mitotic figures, but not atypical forms.¹⁰ In this stage, plasma cells and hemosiderin are more readily identifiable. A biopsy from the nodular stage is unlikely to enter the histologic differential diagnosis with THH. Clinically, there are 4 variants of Kaposi sarcoma: the classic or sporadic form, an endemic form, iatrogenic, and AIDS associated. Overall, it is more common in males and can occur at any age.¹⁰ Human herpesvirus 8 is seen in all forms, and infected cells can be highlighted by the immunohistochemical stain for latent nuclear antigen 1.^9,10 

Angiosarcoma is a malignant endothelial tumor of soft tissue, skin, bone, and visceral organs.^11,12 Clinically, cutaneous angiosarcoma can present in a variety of ways, including single or multiple bluish red lesions that can ulcerate or bleed; violaceous nodules or plaques; and hematomalike lesions that can mimic epithelial neoplasms including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.^11,13,14 The cutaneous lesions most commonly occur on sun-exposed skin, particularly on the face and scalp.¹² Other clinical variants that are important to recognize are postradiation angiosarcoma, characterized by MYC gene amplification, and lymphedema-associated angiosarcoma (Stewart-Treves syndrome). Angiosarcoma can have a variety of morphologic features, ranging from well to poorly differentiated. Classically, angiosarcoma is characterized by infiltrating vascular spaces lined by atypical endothelial cells (Figure 4). Poorly differentiated angiosarcoma can demonstrate spindle, epithelioid, or polygonal cells with increased mitotic activity, pleomorphism, and irregular vascular spaces.¹¹ Endothelial markers such as ERG (erythroblast transformation specific-related gene)(nuclear) and CD31 (membranous) can be used to aid in the diagnosis of a poorly differentiated lesion. Epithelioid angiosarcoma also occasionally stains with cytokeratins.^13,14  

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰ 

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰ 

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰ 

To the Editor:

Hailey-Hailey disease (HHD), or familial benign chronic pemphigus, is a genetic disorder caused by an autosomal-dominant mutation in ATPase secretory pathway Ca²⁺ transporting 1 gene, ATP2C1, which disrupts intracellular calcium signaling and blocks synthesis of junctional proteins required for cell-cell adhesion.^1,2 As a result, patients develop acantholysis of the suprabasilar epidermis resulting in chronic flaccid blisters and erosions, particularly in intertriginous areas.³ Patients often report associated itching, pain, and burning, and they frequently present with secondary polymicrobial infections.⁴ Although HHD is genetic, patients may present without a family history due to variable expressivity and sporadic germline mutations.⁵ Therapeutic options are numerous, and patients may attempt many treatments before a benefit is observed.⁴ Local disease improvement was noted in a case series of 3 patients treated with electron beam radiotherapy with no disease recurrence in treated sites at 38, 33, and 9 months’ follow-up.⁶ Herein, we present a case of HHD refractory to numerous prior therapies that was successfully treated with electron beam radiotherapy, highlighting the potential role for palliative radiotherapy in select refractory cases of HHD.

A 35-year-old woman with a 7-year of history of HHD presented with severe recalcitrant disease including extensive erosive patches and plaques in the intertriginous areas of the bilateral axillae, groin, and inframammary folds (Figure 1). The skin eruptions first appeared at 28 years of age after her last pregnancy and continued as painful blistering that worsened with each menstrual cycle. Initially the affected desquamated skin would heal between menstrual cycles, but large areas of desquamation remained unhealed in the groin and inframammary regions throughout her full menstrual cycles by the time of referral. Family history included 4 family members with HHD: 2 aunts, an uncle, and a cousin on the paternal side of her family. Over a 7-year period, treatment with clobetasol cream, clindamycin gel, tacrolimus ointment, doxycycline, dapsone, cyclosporine, methotrexate, etanercept, isotretinoin, and prednisone (15 mg every other day) all failed. Most recently, axillary abobotulinumtoxinA injections were attempted but failed. She had been prednisone dependent for more than 1 year. Due to the ongoing refractory disease, she was referred to radiation oncology to discuss radiotherapy treatment options.

One month after treatment she had total resolution of the erosive patches and plaques with mild residual hyperpigmentation in the axillae, establishing that radiation therapy was reasonably effective. To lower the total radiation dose and decrease the risk of radiation-induced malignancy, we treated the bilateral groin and the inframammary region with a treatment schedule of 8 Gy in 2 fractions at a higher dose of 4 Gy per fraction instead of 2 Gy. At 12 days posttreatment, she had a dramatic response in the groin and a mixed response in the inframammary region, with a focus that had not yet regressed. Given the dramatic response in the treated sites, the patient requested treatment to the right side of the neck. Thus, we treated this area with a similar 8 Gy in 2 fractions, and an additional 6 Gy in 2 fractions boost was added to the slow responding focus in the inframammary fold for a total of 14 Gy in 4 fractions. The patient tolerated all treatments well with mild grade 1 skin irritation that was unlike the blistering of the typical HHD flares. Two months following completion of the first course of radiotherapy to the axillae and 2 weeks from the most recent course, she tapered off her prednisone regimen (15 mg every other day) but had a relapse of disease with her subsequent menstrual cycles that presented as a blistering skin reaction in the inframammary region, which healed in response to restarting steroids. This flare was less severe than those prior to radiotherapy. At 10 months posttreatment, the patient was free of disease in the neck and axillae (Figure 2). She continued to have relapses in the inframammary region with menstrual cycles and noted new disease in the popliteal regions; however, the relapses were less severe, and her skin had improved more with radiation than any of the prior therapies.

To the Editor:

Hailey-Hailey disease (HHD), or familial benign chronic pemphigus, is a genetic disorder caused by an autosomal-dominant mutation in ATPase secretory pathway Ca²⁺ transporting 1 gene, ATP2C1, which disrupts intracellular calcium signaling and blocks synthesis of junctional proteins required for cell-cell adhesion.^1,2 As a result, patients develop acantholysis of the suprabasilar epidermis resulting in chronic flaccid blisters and erosions, particularly in intertriginous areas.³ Patients often report associated itching, pain, and burning, and they frequently present with secondary polymicrobial infections.⁴ Although HHD is genetic, patients may present without a family history due to variable expressivity and sporadic germline mutations.⁵ Therapeutic options are numerous, and patients may attempt many treatments before a benefit is observed.⁴ Local disease improvement was noted in a case series of 3 patients treated with electron beam radiotherapy with no disease recurrence in treated sites at 38, 33, and 9 months’ follow-up.⁶ Herein, we present a case of HHD refractory to numerous prior therapies that was successfully treated with electron beam radiotherapy, highlighting the potential role for palliative radiotherapy in select refractory cases of HHD.

A 35-year-old woman with a 7-year of history of HHD presented with severe recalcitrant disease including extensive erosive patches and plaques in the intertriginous areas of the bilateral axillae, groin, and inframammary folds (Figure 1). The skin eruptions first appeared at 28 years of age after her last pregnancy and continued as painful blistering that worsened with each menstrual cycle. Initially the affected desquamated skin would heal between menstrual cycles, but large areas of desquamation remained unhealed in the groin and inframammary regions throughout her full menstrual cycles by the time of referral. Family history included 4 family members with HHD: 2 aunts, an uncle, and a cousin on the paternal side of her family. Over a 7-year period, treatment with clobetasol cream, clindamycin gel, tacrolimus ointment, doxycycline, dapsone, cyclosporine, methotrexate, etanercept, isotretinoin, and prednisone (15 mg every other day) all failed. Most recently, axillary abobotulinumtoxinA injections were attempted but failed. She had been prednisone dependent for more than 1 year. Due to the ongoing refractory disease, she was referred to radiation oncology to discuss radiotherapy treatment options.

One month after treatment she had total resolution of the erosive patches and plaques with mild residual hyperpigmentation in the axillae, establishing that radiation therapy was reasonably effective. To lower the total radiation dose and decrease the risk of radiation-induced malignancy, we treated the bilateral groin and the inframammary region with a treatment schedule of 8 Gy in 2 fractions at a higher dose of 4 Gy per fraction instead of 2 Gy. At 12 days posttreatment, she had a dramatic response in the groin and a mixed response in the inframammary region, with a focus that had not yet regressed. Given the dramatic response in the treated sites, the patient requested treatment to the right side of the neck. Thus, we treated this area with a similar 8 Gy in 2 fractions, and an additional 6 Gy in 2 fractions boost was added to the slow responding focus in the inframammary fold for a total of 14 Gy in 4 fractions. The patient tolerated all treatments well with mild grade 1 skin irritation that was unlike the blistering of the typical HHD flares. Two months following completion of the first course of radiotherapy to the axillae and 2 weeks from the most recent course, she tapered off her prednisone regimen (15 mg every other day) but had a relapse of disease with her subsequent menstrual cycles that presented as a blistering skin reaction in the inframammary region, which healed in response to restarting steroids. This flare was less severe than those prior to radiotherapy. At 10 months posttreatment, the patient was free of disease in the neck and axillae (Figure 2). She continued to have relapses in the inframammary region with menstrual cycles and noted new disease in the popliteal regions; however, the relapses were less severe, and her skin had improved more with radiation than any of the prior therapies.

To the Editor:

Hailey-Hailey disease (HHD), or familial benign chronic pemphigus, is a genetic disorder caused by an autosomal-dominant mutation in ATPase secretory pathway Ca²⁺ transporting 1 gene, ATP2C1, which disrupts intracellular calcium signaling and blocks synthesis of junctional proteins required for cell-cell adhesion.^1,2 As a result, patients develop acantholysis of the suprabasilar epidermis resulting in chronic flaccid blisters and erosions, particularly in intertriginous areas.³ Patients often report associated itching, pain, and burning, and they frequently present with secondary polymicrobial infections.⁴ Although HHD is genetic, patients may present without a family history due to variable expressivity and sporadic germline mutations.⁵ Therapeutic options are numerous, and patients may attempt many treatments before a benefit is observed.⁴ Local disease improvement was noted in a case series of 3 patients treated with electron beam radiotherapy with no disease recurrence in treated sites at 38, 33, and 9 months’ follow-up.⁶ Herein, we present a case of HHD refractory to numerous prior therapies that was successfully treated with electron beam radiotherapy, highlighting the potential role for palliative radiotherapy in select refractory cases of HHD.

A 35-year-old woman with a 7-year of history of HHD presented with severe recalcitrant disease including extensive erosive patches and plaques in the intertriginous areas of the bilateral axillae, groin, and inframammary folds (Figure 1). The skin eruptions first appeared at 28 years of age after her last pregnancy and continued as painful blistering that worsened with each menstrual cycle. Initially the affected desquamated skin would heal between menstrual cycles, but large areas of desquamation remained unhealed in the groin and inframammary regions throughout her full menstrual cycles by the time of referral. Family history included 4 family members with HHD: 2 aunts, an uncle, and a cousin on the paternal side of her family. Over a 7-year period, treatment with clobetasol cream, clindamycin gel, tacrolimus ointment, doxycycline, dapsone, cyclosporine, methotrexate, etanercept, isotretinoin, and prednisone (15 mg every other day) all failed. Most recently, axillary abobotulinumtoxinA injections were attempted but failed. She had been prednisone dependent for more than 1 year. Due to the ongoing refractory disease, she was referred to radiation oncology to discuss radiotherapy treatment options.

One month after treatment she had total resolution of the erosive patches and plaques with mild residual hyperpigmentation in the axillae, establishing that radiation therapy was reasonably effective. To lower the total radiation dose and decrease the risk of radiation-induced malignancy, we treated the bilateral groin and the inframammary region with a treatment schedule of 8 Gy in 2 fractions at a higher dose of 4 Gy per fraction instead of 2 Gy. At 12 days posttreatment, she had a dramatic response in the groin and a mixed response in the inframammary region, with a focus that had not yet regressed. Given the dramatic response in the treated sites, the patient requested treatment to the right side of the neck. Thus, we treated this area with a similar 8 Gy in 2 fractions, and an additional 6 Gy in 2 fractions boost was added to the slow responding focus in the inframammary fold for a total of 14 Gy in 4 fractions. The patient tolerated all treatments well with mild grade 1 skin irritation that was unlike the blistering of the typical HHD flares. Two months following completion of the first course of radiotherapy to the axillae and 2 weeks from the most recent course, she tapered off her prednisone regimen (15 mg every other day) but had a relapse of disease with her subsequent menstrual cycles that presented as a blistering skin reaction in the inframammary region, which healed in response to restarting steroids. This flare was less severe than those prior to radiotherapy. At 10 months posttreatment, the patient was free of disease in the neck and axillae (Figure 2). She continued to have relapses in the inframammary region with menstrual cycles and noted new disease in the popliteal regions; however, the relapses were less severe, and her skin had improved more with radiation than any of the prior therapies.

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

The pathogenesis of coronavirus disease 2019 (COVID-19), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is not yet completely understood. Thus far, it is known to affect multiple organ systems, including gastrointestinal, neurological, and cardiovascular, with typical clinical symptoms of COVID-19 including fever, cough, myalgia, headache, anosmia, and diarrhea.¹ This multiorgan attack may be secondary to an exaggerated inflammatory reaction with vasculopathy and possibly a hypercoagulable state. Skin manifestations also are prevalent in COVID-19, and they often result in polymorphous presentations.² This article aims to summarize cutaneous clinical signs of COVID-19 so that dermatologists can promptly identify and manage COVID-19 and prevent its spread.

Methods

A PubMed search of articles indexed for MEDLINE was conducted on June 30, 2020. The literature included observational studies, case reports, and literature reviews from January 1, 2020, to June 30, 2020. Search terms included COVID-19, SARS-CoV-2, and coronavirus used in combination with cutaneous, skin, and dermatology. All of the resulting articles were then reviewed for relevance to the cutaneous manifestations of COVID-19. Only confirmed cases of COVID-19 infection were included in this review; suspected unconfirmed cases were excluded. Further exclusion criteria included articles that discussed dermatology in the time of COVID-19 that did not explicitly address its cutaneous manifestations. The remaining literature was evaluated to provide dermatologists and patients with a concise resource for the cutaneous signs and symptoms of COVID-19. Data extracted from the literature included geographic region, number of patients with skin findings, status of COVID-19 infection and timeline, and cutaneous signs. If a cutaneous sign was not given a clear diagnosis in the literature, the senior authors (A.L. and J.J.) assigned it to its most similar classification to aid in ease of understanding and clarity for the readers.

Results

A search of the key terms resulted in 75 articles published in the specified date range. After excluding overtly irrelevant articles and dermatologic conditions in the time of COVID-19 without confirmed SARS-CoV-2 infection, 25 articles ultimately met inclusion criteria. Relevant references from the articles also were explored for cutaneous dermatologic manifestations of COVID-19. Cutaneous manifestations that were repeatedly reported included chilblainlike lesions; acrocyanosis; urticaria; pityriasis rosea–like cutaneous eruption; erythema multiforme–like, vesiculopapular, and morbilliform eruptions; petechiae; livedo reticularis; and purpuric livedo reticularis (dermatologists may label this stellate purpura). Fewer but nonetheless notable cases of androgenic alopecia, periorbital dyschromia, and herpes zoster exacerbations also were documented. The Table summarizes the reported integumentary findings. The eTable groups the common findings and describes patient age, time to onset of cutaneous sign, and any prognostic significance as seen in the literature.

Chilblainlike Lesions and Acrocyanosis
Chilblainlike lesions are edematous eruptions of the fingers and toes. They usually do not scar and are described as erythematous to violaceous papules and macules with possible bullae on the digits. Skin biopsies demonstrate a histopathologic pattern of vacuolar interface dermatitis with necrotic keratinocytes and a thickened basement membrane. Lymphocytic infiltrate presents in a perieccrine distribution, occasionally with plasma cells. The dermatopathologic findings mimic those of chilblain lupus but lack dermal edema.³

These eruptions have been reported in cases of COVID-19 that more frequently affect children and young adults. They usually resolve over the course of viral infection, averaging within 14 days. Chilblainlike eruptions often are associated with pruritus or pain. They commonly are asymmetrical and appear more often on the toes than the fingers.⁴ In cases of COVID-19 that lack systemic symptoms, chilblainlike lesions have been seen on the dorsal fingers as the first presenting sign of infection.⁵

Acral erythema and chilblainlike lesions frequently have been associated with milder infection. Another positive prognostic indicator is the manifestation of these signs in younger individuals.³

Morbilliform Exanthem
The morbilliform exanthem associated with COVID-19 also typically presents in patients with milder disease. It often affects the buttocks, lower abdomen, and thighs, but spares the palms, soles, and mucosae.⁴ This skin sign, which may start out as a generalized morbilliform exanthem, has been seen to morph into macular hemorrhagic purpura on the legs. These cutaneous lesions typically spontaneously resolve.⁸

In a case report by Najarian,⁶ a morbilliform exanthem was seen on the legs, arms, and trunk of a patient who was otherwise asymptomatic but tested positive for COVID-19. The morbilliform exanthem then became confluent on the trunk. Notably, the patient reported pain of the hands and feet.⁶

Another case report described a patient with edematous annular plaques on the palms, neck, and upper extremities who presented solely with fever.⁷ The biopsy specimen was nonspecific but indicated a viral exanthem. Histopathology showed perivascular lymphocytic infiltrate, dermal edema and vacuoles, spongiosis, dyskeratotic basilar keratinocytes, and few neutrophils without eosinophils.⁷

Eczematous Eruption
A confluent eczematous eruption in the flexural areas, the antecubital fossae, and axillary folds has been found in COVID-19 patients.^21,22 An elderly patient with severe COVID-19 developed a squamous erythematous periumbilical patch 1 day after hospital admission. The cutaneous eruption rapidly progressed to digitate scaly plaques on the trunk, thighs, and flank. A biopsy specimen showed epidermal spongiosis, vesicles containing lymphocytes, and Langerhans cells. The upper dermis demonstrated a lymphohistiocytic infiltrate.²³

Pityriasis Rosea–Like Eruption
In Iran, a COVID-19–infected patient developed an erythematous papulosquamous eruption with a herald patch and trailing scales 3 days after viral symptoms, resembling that of pityriasis rosea.²⁴ Nests of Langerhans cells within the epidermis are seen in many viral exanthems, including cases of COVID-19 and pityriasis rosea.²⁵

Urticaria
According to a number of case reports, urticarial lesions have been the first presenting sign of COVID-19 infection, most resolving with antihistamines.^10,11 Some patients with more severe symptoms have had widespread urticaria. An urticarial exanthem appearing on the bilateral thighs and buttocks may be the initial sign of infection.^12,15 Pruritic erythematous plaques over the face and acral areas is another initial sign. Interestingly, pediatric patients have reported nonpruritic urticaria.⁹

Urticaria also has been seen as a late dermatologic sign of viral infection. After battling relentless viral infection for 1 month, a pruritic, confluent, ill-defined eruption appeared along a patient’s trunk, back, and proximal extremities. Histopathologic examination concluded a perivascular lymphocytic infiltrate and dilated vessels in the dermis. The urticaria resolved a week later, and the patient’s nasopharyngeal swab finally came back negative.¹³

Vesiculopapular Eruption
Vesicles mimicking those of chickenpox have been reported. A study of 375 confirmed cases of COVID-19 by Galván Casas et al¹² showed a 9% incidence of this vesicular eruption. A study by Sachdeva et al⁸ revealed vesicular eruptions in 25 of 72 patients. Pruritic papules and vesicles may resemble Grover disease. This cutaneous sign may be seen in the submammary folds, on the hips, or diffusely over the body.

Erythema Multiforme–Like Eruption
Targetoid lesions similar to those of erythema multiforme erupted in 2 of 27 patients with mild COVID-19 infection in a review by Wollina et al.⁴ In a study of 4 patients with erythema multiforme–like eruptions after COVID-19 symptoms resolved, 3 had palatal petechiae. Two of 4 patients had pseudovesicles in the center of the erythematous targetoid patches.²⁶ Targetoid lesions on the extremities have been reported in pediatric patients with COVID-19 infections. These patients often present without any typical viral symptoms but rather just a febrile exanthem or exanthem alone. Thus, to minimize spread of the virus, it is vital to recognize COVID-19 infection early in patients with a viral exanthem during the time of high COVID-19 incidence.⁴

Livedo Reticularis
In the United States, a case series reported 2 patients with transient livedo reticularis throughout the course of COVID-19 infection. The cutaneous eruption resembled erythema ab igne, but there was no history of exposure to heat.¹⁶

Stellate Purpura
In severe COVID-19 infection, a reticulated nonblanching purpura on the buttocks has been reported to demonstrate pauci-inflammatory vascular thrombosis, complement membrane attack complex deposition, and endothelial injury on dermatopathology. Stellate purpura on palmoplantar surfaces also has shown arterial thrombosis in the deep dermis due to complement deposition.¹⁷

Petechiae and Purpura
A morbilliform exanthem may develop into significant petechiae in the popliteal fossae, buttocks, and thighs. A punch biopsy specimen demonstrates a perivascular lymphocytic infiltrate with erythrocyte extravasation and papillary dermal edema with dyskeratotic cells.¹⁸ Purpura of the lower extremities may develop, with histopathology showing fibrinoid necrosis of small vessel walls, neutrophilic infiltrate with karyorrhexis, and granular complement deposition.¹⁹

In Thailand, a patient was misdiagnosed with dengue after presenting with petechiae and low platelet count.²⁰ Further progression of the viral illness resulted in respiratory symptoms. Subsequently, the patient tested positive for COVID-19. This case demonstrates that cutaneous signs of many sorts may be the first presenting signs of COVID-19, even prior to febrile symptoms.²⁰

Androgenic Alopecia
Studies have shown that androgens are related in the pathogenesis of COVID-19. Coronavirus disease 2019 uses a cellular co-receptor, TMPRSS2, which is androgen regulated.²⁷ In a study of 41 males with COVID-19, 29 had androgenic alopecia. However, this is only a correlation, and causation cannot be concluded here. It cannot be determined from this study whether androgenic alopecia is a risk factor, result of COVID-19, or confounder.²⁸

Exaggerated Herpes Zoster
Shors²⁹ reported a herpes zoster eruption in a patient who had symptoms of COVID-19 for 1 week. Further testing confirmed COVID-19 infection, and despite prompt treatment with valacyclovir, the eruption was slow to resolve. The patient then experienced severe postherpetic neuralgia for more than 4 weeks, even with treatment with gabapentin and lidocaine. It is hypothesized that because of the major inflammatory response caused by COVID-19, an exaggerated inflammation occurred in the dorsal root ganglion, resulting in relentless herpes zoster infection.²⁹

Mottled Skin
Born at term, a 15-day-old neonate presented with sepsis and mottling of the skin. The patient did not have any typical COVID-19 symptoms, such as diarrhea or cough, but tested positive for COVID-19.³⁰

Periorbital Dyschromia
Kalner and Vergilis³¹ reported 2 cases of periorbital dyschromia prior to any other COVID-19 infection symptoms. The discoloration improved with resolution of ensuing viral symptoms.³¹

Comment

Many dermatologic signs of COVID-19 have been identified. Their individual frequency and association with viral severity will become more apparent as more cases are reported. So far during this pandemic, common dermatologic manifestations have been polymorphic in clinical presentation.

Onset of Skin Manifestations
The timeline of skin signs and COVID-19 symptoms varies from the first reported sign to weeks after symptom resolution. In the Region of Murcia, Spain, Pérez-Suárez et al¹⁴ collected data on cutaneous signs of patients with COVID-19. Of the patients studied, 9 had tests confirming COVID-19 infection. Truncal urticaria, sacral ulcers, acrocyanosis, and erythema multiforme were all reported in patients more than 2 weeks after symptom onset. One case of tinea infection also was reported 4 days after fever and respiratory symptoms began.¹⁴

Presentation
Coronavirus disease 2019 has affected the skin of both the central thorax and peripheral locations. In a study of 72 patients with cutaneous signs of COVID-19 by Sachdeva et al,⁸ a truncal distribution was most common, but 14 patients reported acral site involvement. Sachdeva et al⁸ reported urticarial reactions in 7 of 72 patients with cutaneous signs. A painful acral cyanosis was seen in 11 of 72 patients. Livedo reticularis presented in 2 patients, and only 1 patient had petechiae. Cutaneous signs were the first indicators of viral infection in 9 of 72 patients; 52 patients presented with respiratory symptoms first. All of the reported cutaneous signs spontaneously resolved within 10 days.⁸

Recalcati³² reviewed 88 patients with COVID-19, and 18 had cutaneous signs at initial onset of viral infection or during hospitalization. The most common integumentary sign reported in this study was erythema, followed by diffuse urticaria, and then a vesicular eruption resembling varicella infection.³²

Some less common phenomena have been identified in patients with COVID-19, including androgenic alopecia, exaggerated herpes zoster and postherpetic neuralgia, mottled skin, and periorbital dyschromia. Being aware of these complications may help in early treatment, diagnosis, and even prevention of viral spread.

Pathogenesis of Skin Manifestations
Few breakthroughs have been made in understanding the pathogenesis of skin manifestations of SARS-CoV-2. Acral ischemia may be a manifestation of COVID-19’s association with hypercoagulation. Increasing fibrinogen and prothrombin times lead to disseminated intravascular coagulation and microthrombi. These tiny blood clots then lodge in blood vessels and cause acral cyanosis and subsequent gangrene.² The proposed mechanism behind this clinical manifestation in younger populations is the hypercoagulable state that COVID-19 creates. Conversely, acral erythema and chilblainlike lesions in older patients are thought to be from acral ischemia as a response to insufficient type 1 interferons. This pathophysiologic mechanism is indicative of a worse prognosis due to the large role that type 1 interferons play in antiviral responses. Coronavirus disease 2019 similarly triggers type 1 interferons; thus, their efficacy positively correlates with good disease prognosis.³

Similarly, the pathogenesis for livedo reticularis in patients with COVID-19 can only be hypothesized. Infected patients are in a hypercoagulable state, and in these cases, it was uncertain whether this was due to a disseminated intravascular coagulation, cold agglutinins, cryofibrinogens, or lupus anticoagulant.¹⁶

Nonetheless, it can be difficult to separate the primary event between vasculopathy or vasculitis in larger vessel pathology specimens. Some of the studies’ pathology reports discuss a granulocytic infiltrate and red blood cell extravasation, which represent small vessel vasculitis. However, the gangrene and necrosing livedo represent vasculopathy events. A final conclusion about the pathogenesis cannot be made without further clinical and histopathologic evaluation.

Histopathology
Biopsy specimens of reported morbilliform eruptions have demonstrated thrombosed vessels with evidence of necrosis and granulocytic infiltrate.²⁵ Another biopsy specimen of a widespread erythematous exanthem demonstrated extravasated red blood cells and vessel wall damage similar to thrombophilic arteritis. Other reports of histopathology showed necrotic keratinocytes and lymphocytic satellitosis at the dermoepidermal junction, resembling Grover disease. These cases demonstrating necrosis suggest a strong cytokine reaction from the virus.²⁵ A concern with these biopsy findings is that morbilliform eruptions generally show dilated vessels with lymphocytes, and these biopsy findings are consistent with a cutaneous small vessel vasculitis. Additionally, histopathologic evaluation of purpuric eruptions has shown erythrocyte extravasation and granulocytic infiltrate indicative of a cutaneous small vessel vasculitis.

Although most reported cases of cutaneous signs of COVID-19 do not have histopathologic reports, Yao et al³³ conducted a dermatopathologic study that investigated the tissue in deceased patients who had COVID-19. This pathology showed hyaline thrombi within the small vessels of the skin, likely leading to the painful acral ischemia. Similarly, Yao et al³³ reported autopsies finding hyaline thrombi within the small vessels of the lungs. More research should be done to explore this pathogenesis as part of prognostic factors and virulence.

Conclusion

Cutaneous signs may be the first reported symptom of COVID-19 infection, and dermatologists should be prepared to identify them. This review may be used as a guide for physicians to quickly identify potential infection as well as further understand the pathogenesis related to COVID-19. Future research is necessary to determine the dermatologic pathogenesis, infectivity, and prevalence of cutaneous manifestations of COVID-19. It also will be important to explore if vasculopathic lesions predict more severe multisystem disease.

The pathogenesis of coronavirus disease 2019 (COVID-19), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is not yet completely understood. Thus far, it is known to affect multiple organ systems, including gastrointestinal, neurological, and cardiovascular, with typical clinical symptoms of COVID-19 including fever, cough, myalgia, headache, anosmia, and diarrhea.¹ This multiorgan attack may be secondary to an exaggerated inflammatory reaction with vasculopathy and possibly a hypercoagulable state. Skin manifestations also are prevalent in COVID-19, and they often result in polymorphous presentations.² This article aims to summarize cutaneous clinical signs of COVID-19 so that dermatologists can promptly identify and manage COVID-19 and prevent its spread.

Methods

A PubMed search of articles indexed for MEDLINE was conducted on June 30, 2020. The literature included observational studies, case reports, and literature reviews from January 1, 2020, to June 30, 2020. Search terms included COVID-19, SARS-CoV-2, and coronavirus used in combination with cutaneous, skin, and dermatology. All of the resulting articles were then reviewed for relevance to the cutaneous manifestations of COVID-19. Only confirmed cases of COVID-19 infection were included in this review; suspected unconfirmed cases were excluded. Further exclusion criteria included articles that discussed dermatology in the time of COVID-19 that did not explicitly address its cutaneous manifestations. The remaining literature was evaluated to provide dermatologists and patients with a concise resource for the cutaneous signs and symptoms of COVID-19. Data extracted from the literature included geographic region, number of patients with skin findings, status of COVID-19 infection and timeline, and cutaneous signs. If a cutaneous sign was not given a clear diagnosis in the literature, the senior authors (A.L. and J.J.) assigned it to its most similar classification to aid in ease of understanding and clarity for the readers.

Results

A search of the key terms resulted in 75 articles published in the specified date range. After excluding overtly irrelevant articles and dermatologic conditions in the time of COVID-19 without confirmed SARS-CoV-2 infection, 25 articles ultimately met inclusion criteria. Relevant references from the articles also were explored for cutaneous dermatologic manifestations of COVID-19. Cutaneous manifestations that were repeatedly reported included chilblainlike lesions; acrocyanosis; urticaria; pityriasis rosea–like cutaneous eruption; erythema multiforme–like, vesiculopapular, and morbilliform eruptions; petechiae; livedo reticularis; and purpuric livedo reticularis (dermatologists may label this stellate purpura). Fewer but nonetheless notable cases of androgenic alopecia, periorbital dyschromia, and herpes zoster exacerbations also were documented. The Table summarizes the reported integumentary findings. The eTable groups the common findings and describes patient age, time to onset of cutaneous sign, and any prognostic significance as seen in the literature.

Chilblainlike Lesions and Acrocyanosis
Chilblainlike lesions are edematous eruptions of the fingers and toes. They usually do not scar and are described as erythematous to violaceous papules and macules with possible bullae on the digits. Skin biopsies demonstrate a histopathologic pattern of vacuolar interface dermatitis with necrotic keratinocytes and a thickened basement membrane. Lymphocytic infiltrate presents in a perieccrine distribution, occasionally with plasma cells. The dermatopathologic findings mimic those of chilblain lupus but lack dermal edema.³

These eruptions have been reported in cases of COVID-19 that more frequently affect children and young adults. They usually resolve over the course of viral infection, averaging within 14 days. Chilblainlike eruptions often are associated with pruritus or pain. They commonly are asymmetrical and appear more often on the toes than the fingers.⁴ In cases of COVID-19 that lack systemic symptoms, chilblainlike lesions have been seen on the dorsal fingers as the first presenting sign of infection.⁵

Acral erythema and chilblainlike lesions frequently have been associated with milder infection. Another positive prognostic indicator is the manifestation of these signs in younger individuals.³

Morbilliform Exanthem
The morbilliform exanthem associated with COVID-19 also typically presents in patients with milder disease. It often affects the buttocks, lower abdomen, and thighs, but spares the palms, soles, and mucosae.⁴ This skin sign, which may start out as a generalized morbilliform exanthem, has been seen to morph into macular hemorrhagic purpura on the legs. These cutaneous lesions typically spontaneously resolve.⁸

In a case report by Najarian,⁶ a morbilliform exanthem was seen on the legs, arms, and trunk of a patient who was otherwise asymptomatic but tested positive for COVID-19. The morbilliform exanthem then became confluent on the trunk. Notably, the patient reported pain of the hands and feet.⁶

Another case report described a patient with edematous annular plaques on the palms, neck, and upper extremities who presented solely with fever.⁷ The biopsy specimen was nonspecific but indicated a viral exanthem. Histopathology showed perivascular lymphocytic infiltrate, dermal edema and vacuoles, spongiosis, dyskeratotic basilar keratinocytes, and few neutrophils without eosinophils.⁷

Eczematous Eruption
A confluent eczematous eruption in the flexural areas, the antecubital fossae, and axillary folds has been found in COVID-19 patients.^21,22 An elderly patient with severe COVID-19 developed a squamous erythematous periumbilical patch 1 day after hospital admission. The cutaneous eruption rapidly progressed to digitate scaly plaques on the trunk, thighs, and flank. A biopsy specimen showed epidermal spongiosis, vesicles containing lymphocytes, and Langerhans cells. The upper dermis demonstrated a lymphohistiocytic infiltrate.²³

Pityriasis Rosea–Like Eruption
In Iran, a COVID-19–infected patient developed an erythematous papulosquamous eruption with a herald patch and trailing scales 3 days after viral symptoms, resembling that of pityriasis rosea.²⁴ Nests of Langerhans cells within the epidermis are seen in many viral exanthems, including cases of COVID-19 and pityriasis rosea.²⁵

Urticaria
According to a number of case reports, urticarial lesions have been the first presenting sign of COVID-19 infection, most resolving with antihistamines.^10,11 Some patients with more severe symptoms have had widespread urticaria. An urticarial exanthem appearing on the bilateral thighs and buttocks may be the initial sign of infection.^12,15 Pruritic erythematous plaques over the face and acral areas is another initial sign. Interestingly, pediatric patients have reported nonpruritic urticaria.⁹

Urticaria also has been seen as a late dermatologic sign of viral infection. After battling relentless viral infection for 1 month, a pruritic, confluent, ill-defined eruption appeared along a patient’s trunk, back, and proximal extremities. Histopathologic examination concluded a perivascular lymphocytic infiltrate and dilated vessels in the dermis. The urticaria resolved a week later, and the patient’s nasopharyngeal swab finally came back negative.¹³

Vesiculopapular Eruption
Vesicles mimicking those of chickenpox have been reported. A study of 375 confirmed cases of COVID-19 by Galván Casas et al¹² showed a 9% incidence of this vesicular eruption. A study by Sachdeva et al⁸ revealed vesicular eruptions in 25 of 72 patients. Pruritic papules and vesicles may resemble Grover disease. This cutaneous sign may be seen in the submammary folds, on the hips, or diffusely over the body.

Erythema Multiforme–Like Eruption
Targetoid lesions similar to those of erythema multiforme erupted in 2 of 27 patients with mild COVID-19 infection in a review by Wollina et al.⁴ In a study of 4 patients with erythema multiforme–like eruptions after COVID-19 symptoms resolved, 3 had palatal petechiae. Two of 4 patients had pseudovesicles in the center of the erythematous targetoid patches.²⁶ Targetoid lesions on the extremities have been reported in pediatric patients with COVID-19 infections. These patients often present without any typical viral symptoms but rather just a febrile exanthem or exanthem alone. Thus, to minimize spread of the virus, it is vital to recognize COVID-19 infection early in patients with a viral exanthem during the time of high COVID-19 incidence.⁴

Livedo Reticularis
In the United States, a case series reported 2 patients with transient livedo reticularis throughout the course of COVID-19 infection. The cutaneous eruption resembled erythema ab igne, but there was no history of exposure to heat.¹⁶

Stellate Purpura
In severe COVID-19 infection, a reticulated nonblanching purpura on the buttocks has been reported to demonstrate pauci-inflammatory vascular thrombosis, complement membrane attack complex deposition, and endothelial injury on dermatopathology. Stellate purpura on palmoplantar surfaces also has shown arterial thrombosis in the deep dermis due to complement deposition.¹⁷

Petechiae and Purpura
A morbilliform exanthem may develop into significant petechiae in the popliteal fossae, buttocks, and thighs. A punch biopsy specimen demonstrates a perivascular lymphocytic infiltrate with erythrocyte extravasation and papillary dermal edema with dyskeratotic cells.¹⁸ Purpura of the lower extremities may develop, with histopathology showing fibrinoid necrosis of small vessel walls, neutrophilic infiltrate with karyorrhexis, and granular complement deposition.¹⁹

In Thailand, a patient was misdiagnosed with dengue after presenting with petechiae and low platelet count.²⁰ Further progression of the viral illness resulted in respiratory symptoms. Subsequently, the patient tested positive for COVID-19. This case demonstrates that cutaneous signs of many sorts may be the first presenting signs of COVID-19, even prior to febrile symptoms.²⁰

Androgenic Alopecia
Studies have shown that androgens are related in the pathogenesis of COVID-19. Coronavirus disease 2019 uses a cellular co-receptor, TMPRSS2, which is androgen regulated.²⁷ In a study of 41 males with COVID-19, 29 had androgenic alopecia. However, this is only a correlation, and causation cannot be concluded here. It cannot be determined from this study whether androgenic alopecia is a risk factor, result of COVID-19, or confounder.²⁸

Exaggerated Herpes Zoster
Shors²⁹ reported a herpes zoster eruption in a patient who had symptoms of COVID-19 for 1 week. Further testing confirmed COVID-19 infection, and despite prompt treatment with valacyclovir, the eruption was slow to resolve. The patient then experienced severe postherpetic neuralgia for more than 4 weeks, even with treatment with gabapentin and lidocaine. It is hypothesized that because of the major inflammatory response caused by COVID-19, an exaggerated inflammation occurred in the dorsal root ganglion, resulting in relentless herpes zoster infection.²⁹

Mottled Skin
Born at term, a 15-day-old neonate presented with sepsis and mottling of the skin. The patient did not have any typical COVID-19 symptoms, such as diarrhea or cough, but tested positive for COVID-19.³⁰

Periorbital Dyschromia
Kalner and Vergilis³¹ reported 2 cases of periorbital dyschromia prior to any other COVID-19 infection symptoms. The discoloration improved with resolution of ensuing viral symptoms.³¹

Comment

Many dermatologic signs of COVID-19 have been identified. Their individual frequency and association with viral severity will become more apparent as more cases are reported. So far during this pandemic, common dermatologic manifestations have been polymorphic in clinical presentation.

Onset of Skin Manifestations
The timeline of skin signs and COVID-19 symptoms varies from the first reported sign to weeks after symptom resolution. In the Region of Murcia, Spain, Pérez-Suárez et al¹⁴ collected data on cutaneous signs of patients with COVID-19. Of the patients studied, 9 had tests confirming COVID-19 infection. Truncal urticaria, sacral ulcers, acrocyanosis, and erythema multiforme were all reported in patients more than 2 weeks after symptom onset. One case of tinea infection also was reported 4 days after fever and respiratory symptoms began.¹⁴

Presentation
Coronavirus disease 2019 has affected the skin of both the central thorax and peripheral locations. In a study of 72 patients with cutaneous signs of COVID-19 by Sachdeva et al,⁸ a truncal distribution was most common, but 14 patients reported acral site involvement. Sachdeva et al⁸ reported urticarial reactions in 7 of 72 patients with cutaneous signs. A painful acral cyanosis was seen in 11 of 72 patients. Livedo reticularis presented in 2 patients, and only 1 patient had petechiae. Cutaneous signs were the first indicators of viral infection in 9 of 72 patients; 52 patients presented with respiratory symptoms first. All of the reported cutaneous signs spontaneously resolved within 10 days.⁸

Recalcati³² reviewed 88 patients with COVID-19, and 18 had cutaneous signs at initial onset of viral infection or during hospitalization. The most common integumentary sign reported in this study was erythema, followed by diffuse urticaria, and then a vesicular eruption resembling varicella infection.³²

Some less common phenomena have been identified in patients with COVID-19, including androgenic alopecia, exaggerated herpes zoster and postherpetic neuralgia, mottled skin, and periorbital dyschromia. Being aware of these complications may help in early treatment, diagnosis, and even prevention of viral spread.

Pathogenesis of Skin Manifestations
Few breakthroughs have been made in understanding the pathogenesis of skin manifestations of SARS-CoV-2. Acral ischemia may be a manifestation of COVID-19’s association with hypercoagulation. Increasing fibrinogen and prothrombin times lead to disseminated intravascular coagulation and microthrombi. These tiny blood clots then lodge in blood vessels and cause acral cyanosis and subsequent gangrene.² The proposed mechanism behind this clinical manifestation in younger populations is the hypercoagulable state that COVID-19 creates. Conversely, acral erythema and chilblainlike lesions in older patients are thought to be from acral ischemia as a response to insufficient type 1 interferons. This pathophysiologic mechanism is indicative of a worse prognosis due to the large role that type 1 interferons play in antiviral responses. Coronavirus disease 2019 similarly triggers type 1 interferons; thus, their efficacy positively correlates with good disease prognosis.³

Similarly, the pathogenesis for livedo reticularis in patients with COVID-19 can only be hypothesized. Infected patients are in a hypercoagulable state, and in these cases, it was uncertain whether this was due to a disseminated intravascular coagulation, cold agglutinins, cryofibrinogens, or lupus anticoagulant.¹⁶

Nonetheless, it can be difficult to separate the primary event between vasculopathy or vasculitis in larger vessel pathology specimens. Some of the studies’ pathology reports discuss a granulocytic infiltrate and red blood cell extravasation, which represent small vessel vasculitis. However, the gangrene and necrosing livedo represent vasculopathy events. A final conclusion about the pathogenesis cannot be made without further clinical and histopathologic evaluation.

Histopathology
Biopsy specimens of reported morbilliform eruptions have demonstrated thrombosed vessels with evidence of necrosis and granulocytic infiltrate.²⁵ Another biopsy specimen of a widespread erythematous exanthem demonstrated extravasated red blood cells and vessel wall damage similar to thrombophilic arteritis. Other reports of histopathology showed necrotic keratinocytes and lymphocytic satellitosis at the dermoepidermal junction, resembling Grover disease. These cases demonstrating necrosis suggest a strong cytokine reaction from the virus.²⁵ A concern with these biopsy findings is that morbilliform eruptions generally show dilated vessels with lymphocytes, and these biopsy findings are consistent with a cutaneous small vessel vasculitis. Additionally, histopathologic evaluation of purpuric eruptions has shown erythrocyte extravasation and granulocytic infiltrate indicative of a cutaneous small vessel vasculitis.

Although most reported cases of cutaneous signs of COVID-19 do not have histopathologic reports, Yao et al³³ conducted a dermatopathologic study that investigated the tissue in deceased patients who had COVID-19. This pathology showed hyaline thrombi within the small vessels of the skin, likely leading to the painful acral ischemia. Similarly, Yao et al³³ reported autopsies finding hyaline thrombi within the small vessels of the lungs. More research should be done to explore this pathogenesis as part of prognostic factors and virulence.

Conclusion

Cutaneous signs may be the first reported symptom of COVID-19 infection, and dermatologists should be prepared to identify them. This review may be used as a guide for physicians to quickly identify potential infection as well as further understand the pathogenesis related to COVID-19. Future research is necessary to determine the dermatologic pathogenesis, infectivity, and prevalence of cutaneous manifestations of COVID-19. It also will be important to explore if vasculopathic lesions predict more severe multisystem disease.

The pathogenesis of coronavirus disease 2019 (COVID-19), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is not yet completely understood. Thus far, it is known to affect multiple organ systems, including gastrointestinal, neurological, and cardiovascular, with typical clinical symptoms of COVID-19 including fever, cough, myalgia, headache, anosmia, and diarrhea.¹ This multiorgan attack may be secondary to an exaggerated inflammatory reaction with vasculopathy and possibly a hypercoagulable state. Skin manifestations also are prevalent in COVID-19, and they often result in polymorphous presentations.² This article aims to summarize cutaneous clinical signs of COVID-19 so that dermatologists can promptly identify and manage COVID-19 and prevent its spread.

Methods

A PubMed search of articles indexed for MEDLINE was conducted on June 30, 2020. The literature included observational studies, case reports, and literature reviews from January 1, 2020, to June 30, 2020. Search terms included COVID-19, SARS-CoV-2, and coronavirus used in combination with cutaneous, skin, and dermatology. All of the resulting articles were then reviewed for relevance to the cutaneous manifestations of COVID-19. Only confirmed cases of COVID-19 infection were included in this review; suspected unconfirmed cases were excluded. Further exclusion criteria included articles that discussed dermatology in the time of COVID-19 that did not explicitly address its cutaneous manifestations. The remaining literature was evaluated to provide dermatologists and patients with a concise resource for the cutaneous signs and symptoms of COVID-19. Data extracted from the literature included geographic region, number of patients with skin findings, status of COVID-19 infection and timeline, and cutaneous signs. If a cutaneous sign was not given a clear diagnosis in the literature, the senior authors (A.L. and J.J.) assigned it to its most similar classification to aid in ease of understanding and clarity for the readers.

Results

A search of the key terms resulted in 75 articles published in the specified date range. After excluding overtly irrelevant articles and dermatologic conditions in the time of COVID-19 without confirmed SARS-CoV-2 infection, 25 articles ultimately met inclusion criteria. Relevant references from the articles also were explored for cutaneous dermatologic manifestations of COVID-19. Cutaneous manifestations that were repeatedly reported included chilblainlike lesions; acrocyanosis; urticaria; pityriasis rosea–like cutaneous eruption; erythema multiforme–like, vesiculopapular, and morbilliform eruptions; petechiae; livedo reticularis; and purpuric livedo reticularis (dermatologists may label this stellate purpura). Fewer but nonetheless notable cases of androgenic alopecia, periorbital dyschromia, and herpes zoster exacerbations also were documented. The Table summarizes the reported integumentary findings. The eTable groups the common findings and describes patient age, time to onset of cutaneous sign, and any prognostic significance as seen in the literature.

Chilblainlike Lesions and Acrocyanosis
Chilblainlike lesions are edematous eruptions of the fingers and toes. They usually do not scar and are described as erythematous to violaceous papules and macules with possible bullae on the digits. Skin biopsies demonstrate a histopathologic pattern of vacuolar interface dermatitis with necrotic keratinocytes and a thickened basement membrane. Lymphocytic infiltrate presents in a perieccrine distribution, occasionally with plasma cells. The dermatopathologic findings mimic those of chilblain lupus but lack dermal edema.³

These eruptions have been reported in cases of COVID-19 that more frequently affect children and young adults. They usually resolve over the course of viral infection, averaging within 14 days. Chilblainlike eruptions often are associated with pruritus or pain. They commonly are asymmetrical and appear more often on the toes than the fingers.⁴ In cases of COVID-19 that lack systemic symptoms, chilblainlike lesions have been seen on the dorsal fingers as the first presenting sign of infection.⁵

Acral erythema and chilblainlike lesions frequently have been associated with milder infection. Another positive prognostic indicator is the manifestation of these signs in younger individuals.³

Morbilliform Exanthem
The morbilliform exanthem associated with COVID-19 also typically presents in patients with milder disease. It often affects the buttocks, lower abdomen, and thighs, but spares the palms, soles, and mucosae.⁴ This skin sign, which may start out as a generalized morbilliform exanthem, has been seen to morph into macular hemorrhagic purpura on the legs. These cutaneous lesions typically spontaneously resolve.⁸

In a case report by Najarian,⁶ a morbilliform exanthem was seen on the legs, arms, and trunk of a patient who was otherwise asymptomatic but tested positive for COVID-19. The morbilliform exanthem then became confluent on the trunk. Notably, the patient reported pain of the hands and feet.⁶

Another case report described a patient with edematous annular plaques on the palms, neck, and upper extremities who presented solely with fever.⁷ The biopsy specimen was nonspecific but indicated a viral exanthem. Histopathology showed perivascular lymphocytic infiltrate, dermal edema and vacuoles, spongiosis, dyskeratotic basilar keratinocytes, and few neutrophils without eosinophils.⁷

Eczematous Eruption
A confluent eczematous eruption in the flexural areas, the antecubital fossae, and axillary folds has been found in COVID-19 patients.^21,22 An elderly patient with severe COVID-19 developed a squamous erythematous periumbilical patch 1 day after hospital admission. The cutaneous eruption rapidly progressed to digitate scaly plaques on the trunk, thighs, and flank. A biopsy specimen showed epidermal spongiosis, vesicles containing lymphocytes, and Langerhans cells. The upper dermis demonstrated a lymphohistiocytic infiltrate.²³

Pityriasis Rosea–Like Eruption
In Iran, a COVID-19–infected patient developed an erythematous papulosquamous eruption with a herald patch and trailing scales 3 days after viral symptoms, resembling that of pityriasis rosea.²⁴ Nests of Langerhans cells within the epidermis are seen in many viral exanthems, including cases of COVID-19 and pityriasis rosea.²⁵

Urticaria
According to a number of case reports, urticarial lesions have been the first presenting sign of COVID-19 infection, most resolving with antihistamines.^10,11 Some patients with more severe symptoms have had widespread urticaria. An urticarial exanthem appearing on the bilateral thighs and buttocks may be the initial sign of infection.^12,15 Pruritic erythematous plaques over the face and acral areas is another initial sign. Interestingly, pediatric patients have reported nonpruritic urticaria.⁹

Urticaria also has been seen as a late dermatologic sign of viral infection. After battling relentless viral infection for 1 month, a pruritic, confluent, ill-defined eruption appeared along a patient’s trunk, back, and proximal extremities. Histopathologic examination concluded a perivascular lymphocytic infiltrate and dilated vessels in the dermis. The urticaria resolved a week later, and the patient’s nasopharyngeal swab finally came back negative.¹³

Vesiculopapular Eruption
Vesicles mimicking those of chickenpox have been reported. A study of 375 confirmed cases of COVID-19 by Galván Casas et al¹² showed a 9% incidence of this vesicular eruption. A study by Sachdeva et al⁸ revealed vesicular eruptions in 25 of 72 patients. Pruritic papules and vesicles may resemble Grover disease. This cutaneous sign may be seen in the submammary folds, on the hips, or diffusely over the body.

Erythema Multiforme–Like Eruption
Targetoid lesions similar to those of erythema multiforme erupted in 2 of 27 patients with mild COVID-19 infection in a review by Wollina et al.⁴ In a study of 4 patients with erythema multiforme–like eruptions after COVID-19 symptoms resolved, 3 had palatal petechiae. Two of 4 patients had pseudovesicles in the center of the erythematous targetoid patches.²⁶ Targetoid lesions on the extremities have been reported in pediatric patients with COVID-19 infections. These patients often present without any typical viral symptoms but rather just a febrile exanthem or exanthem alone. Thus, to minimize spread of the virus, it is vital to recognize COVID-19 infection early in patients with a viral exanthem during the time of high COVID-19 incidence.⁴

Livedo Reticularis
In the United States, a case series reported 2 patients with transient livedo reticularis throughout the course of COVID-19 infection. The cutaneous eruption resembled erythema ab igne, but there was no history of exposure to heat.¹⁶

Stellate Purpura
In severe COVID-19 infection, a reticulated nonblanching purpura on the buttocks has been reported to demonstrate pauci-inflammatory vascular thrombosis, complement membrane attack complex deposition, and endothelial injury on dermatopathology. Stellate purpura on palmoplantar surfaces also has shown arterial thrombosis in the deep dermis due to complement deposition.¹⁷

Petechiae and Purpura
A morbilliform exanthem may develop into significant petechiae in the popliteal fossae, buttocks, and thighs. A punch biopsy specimen demonstrates a perivascular lymphocytic infiltrate with erythrocyte extravasation and papillary dermal edema with dyskeratotic cells.¹⁸ Purpura of the lower extremities may develop, with histopathology showing fibrinoid necrosis of small vessel walls, neutrophilic infiltrate with karyorrhexis, and granular complement deposition.¹⁹

In Thailand, a patient was misdiagnosed with dengue after presenting with petechiae and low platelet count.²⁰ Further progression of the viral illness resulted in respiratory symptoms. Subsequently, the patient tested positive for COVID-19. This case demonstrates that cutaneous signs of many sorts may be the first presenting signs of COVID-19, even prior to febrile symptoms.²⁰

Androgenic Alopecia
Studies have shown that androgens are related in the pathogenesis of COVID-19. Coronavirus disease 2019 uses a cellular co-receptor, TMPRSS2, which is androgen regulated.²⁷ In a study of 41 males with COVID-19, 29 had androgenic alopecia. However, this is only a correlation, and causation cannot be concluded here. It cannot be determined from this study whether androgenic alopecia is a risk factor, result of COVID-19, or confounder.²⁸

Exaggerated Herpes Zoster
Shors²⁹ reported a herpes zoster eruption in a patient who had symptoms of COVID-19 for 1 week. Further testing confirmed COVID-19 infection, and despite prompt treatment with valacyclovir, the eruption was slow to resolve. The patient then experienced severe postherpetic neuralgia for more than 4 weeks, even with treatment with gabapentin and lidocaine. It is hypothesized that because of the major inflammatory response caused by COVID-19, an exaggerated inflammation occurred in the dorsal root ganglion, resulting in relentless herpes zoster infection.²⁹

Mottled Skin
Born at term, a 15-day-old neonate presented with sepsis and mottling of the skin. The patient did not have any typical COVID-19 symptoms, such as diarrhea or cough, but tested positive for COVID-19.³⁰

Periorbital Dyschromia
Kalner and Vergilis³¹ reported 2 cases of periorbital dyschromia prior to any other COVID-19 infection symptoms. The discoloration improved with resolution of ensuing viral symptoms.³¹

Comment

Many dermatologic signs of COVID-19 have been identified. Their individual frequency and association with viral severity will become more apparent as more cases are reported. So far during this pandemic, common dermatologic manifestations have been polymorphic in clinical presentation.

Onset of Skin Manifestations
The timeline of skin signs and COVID-19 symptoms varies from the first reported sign to weeks after symptom resolution. In the Region of Murcia, Spain, Pérez-Suárez et al¹⁴ collected data on cutaneous signs of patients with COVID-19. Of the patients studied, 9 had tests confirming COVID-19 infection. Truncal urticaria, sacral ulcers, acrocyanosis, and erythema multiforme were all reported in patients more than 2 weeks after symptom onset. One case of tinea infection also was reported 4 days after fever and respiratory symptoms began.¹⁴

Presentation
Coronavirus disease 2019 has affected the skin of both the central thorax and peripheral locations. In a study of 72 patients with cutaneous signs of COVID-19 by Sachdeva et al,⁸ a truncal distribution was most common, but 14 patients reported acral site involvement. Sachdeva et al⁸ reported urticarial reactions in 7 of 72 patients with cutaneous signs. A painful acral cyanosis was seen in 11 of 72 patients. Livedo reticularis presented in 2 patients, and only 1 patient had petechiae. Cutaneous signs were the first indicators of viral infection in 9 of 72 patients; 52 patients presented with respiratory symptoms first. All of the reported cutaneous signs spontaneously resolved within 10 days.⁸

Recalcati³² reviewed 88 patients with COVID-19, and 18 had cutaneous signs at initial onset of viral infection or during hospitalization. The most common integumentary sign reported in this study was erythema, followed by diffuse urticaria, and then a vesicular eruption resembling varicella infection.³²

Some less common phenomena have been identified in patients with COVID-19, including androgenic alopecia, exaggerated herpes zoster and postherpetic neuralgia, mottled skin, and periorbital dyschromia. Being aware of these complications may help in early treatment, diagnosis, and even prevention of viral spread.

Pathogenesis of Skin Manifestations
Few breakthroughs have been made in understanding the pathogenesis of skin manifestations of SARS-CoV-2. Acral ischemia may be a manifestation of COVID-19’s association with hypercoagulation. Increasing fibrinogen and prothrombin times lead to disseminated intravascular coagulation and microthrombi. These tiny blood clots then lodge in blood vessels and cause acral cyanosis and subsequent gangrene.² The proposed mechanism behind this clinical manifestation in younger populations is the hypercoagulable state that COVID-19 creates. Conversely, acral erythema and chilblainlike lesions in older patients are thought to be from acral ischemia as a response to insufficient type 1 interferons. This pathophysiologic mechanism is indicative of a worse prognosis due to the large role that type 1 interferons play in antiviral responses. Coronavirus disease 2019 similarly triggers type 1 interferons; thus, their efficacy positively correlates with good disease prognosis.³

Similarly, the pathogenesis for livedo reticularis in patients with COVID-19 can only be hypothesized. Infected patients are in a hypercoagulable state, and in these cases, it was uncertain whether this was due to a disseminated intravascular coagulation, cold agglutinins, cryofibrinogens, or lupus anticoagulant.¹⁶

Nonetheless, it can be difficult to separate the primary event between vasculopathy or vasculitis in larger vessel pathology specimens. Some of the studies’ pathology reports discuss a granulocytic infiltrate and red blood cell extravasation, which represent small vessel vasculitis. However, the gangrene and necrosing livedo represent vasculopathy events. A final conclusion about the pathogenesis cannot be made without further clinical and histopathologic evaluation.

Histopathology
Biopsy specimens of reported morbilliform eruptions have demonstrated thrombosed vessels with evidence of necrosis and granulocytic infiltrate.²⁵ Another biopsy specimen of a widespread erythematous exanthem demonstrated extravasated red blood cells and vessel wall damage similar to thrombophilic arteritis. Other reports of histopathology showed necrotic keratinocytes and lymphocytic satellitosis at the dermoepidermal junction, resembling Grover disease. These cases demonstrating necrosis suggest a strong cytokine reaction from the virus.²⁵ A concern with these biopsy findings is that morbilliform eruptions generally show dilated vessels with lymphocytes, and these biopsy findings are consistent with a cutaneous small vessel vasculitis. Additionally, histopathologic evaluation of purpuric eruptions has shown erythrocyte extravasation and granulocytic infiltrate indicative of a cutaneous small vessel vasculitis.

Although most reported cases of cutaneous signs of COVID-19 do not have histopathologic reports, Yao et al³³ conducted a dermatopathologic study that investigated the tissue in deceased patients who had COVID-19. This pathology showed hyaline thrombi within the small vessels of the skin, likely leading to the painful acral ischemia. Similarly, Yao et al³³ reported autopsies finding hyaline thrombi within the small vessels of the lungs. More research should be done to explore this pathogenesis as part of prognostic factors and virulence.

Conclusion

Cutaneous signs may be the first reported symptom of COVID-19 infection, and dermatologists should be prepared to identify them. This review may be used as a guide for physicians to quickly identify potential infection as well as further understand the pathogenesis related to COVID-19. Future research is necessary to determine the dermatologic pathogenesis, infectivity, and prevalence of cutaneous manifestations of COVID-19. It also will be important to explore if vasculopathic lesions predict more severe multisystem disease.

Office-based phototherapy practices have closed or are operating below capacity because of the coronavirus disease 2019 (COVID-19) pandemic.¹ Social distancing measures to reduce virus transmission are a significant driving factor.^1-3 In the age of biologics, other options requiring fewer patient visits are available, such as UVB phototherapy. UV phototherapy is considered first line when more than 10% of the body surface area is affected.⁴ Although phototherapy often is performed in the office, it also may be delivered at home.² Home-based phototherapy is safe, effective, and similar in cost to office-based phototherapy.⁴ Currently, there are limited COVID-19–specific guidelines for home-based phototherapy.

The risks and sequelae of COVID-19 are still being investigated, with cases varying by location. As such, local and national public health recommendations are evolving. Dermatologists must make individualized decisions about practice services, as local restrictions differ. As office-based phototherapy services may struggle to implement mitigation strategies, home-based phototherapy is an increasingly viable treatment option.^1,4,5 Patient benefits of home therapy include improved treatment compliance; greater patient satisfaction; reduced travel/waiting time; and reduced long-term cost, including co-pays, depending on insurance coverage.^2,4

We aim to provide recommendations on home-based phototherapy during the pandemic. Throughout the decision-making process, careful consideration of safety, risks, benefits, and treatment options for physicians, staff, and patients will be vital to the successful implementation of home-based phototherapy. Our recommendations are based on maximizing benefits and minimizing risks.

Considerations for Physicians

Physicians should take the following steps when assessing if home phototherapy is an option for each patient.^1,2,4

• Determine patient eligibility for phototherapy treatment if currently not on phototherapy

• Carefully review patient and provider requirements for home phototherapy supplier

• Review patient history of treatment compliance

• Determine insurance coverage and consider exclusion criteria

• Review prior treatments

• Provide education on side effects

• Provide education on signs of adequate treatment response

• Indicate the type of UV light and unit on the prescription

• Consider whether the patient is in the maintenance or initiation phase when providing recommendations

• Work with the supplier if the light therapy unit is denied by submitting an appeal or prescribing a different unit

• Follow up with telemedicine to assess treatment effectiveness and monitor for adverse effects

Considerations for Patients

Counsel patients to weigh the risks and benefits of home phototherapy prescription and usage.^1,2,4

• Evaluate cost

• Carefully review patient and provider requirements for home phototherapy supplier

• Ensure a complete understanding of treatment schedule

• Properly utilize protective equipment (eg, genital shields for men, eye shields for all)

• Avoid sharing phototherapy units with household members

• Disinfect and maintain units

• Maintain proper ventilation of spaces

• Maintain treatment log

• Attend follow-up

Treatment Alternatives

For patients with severe psoriasis, there are alternative treatments to office and home phototherapy. Biologics, immunosuppressive therapies, and other treatment options may be considered on a case-by-case basis.^3,4,6 Currently, recommendations for the risk of COVID-19 with biologics or systemic immunosuppressive therapies remains inconsistent and should be carefully considered when providing alternative treatments.^7-11

Final Thoughts

As restrictions are lifted according to local public health measures, prepandemic office phototherapy practices may resume operations. Home phototherapy is a practical and effective alternative for treatment of psoriasis when access to the office setting is limited.

Office-based phototherapy practices have closed or are operating below capacity because of the coronavirus disease 2019 (COVID-19) pandemic.¹ Social distancing measures to reduce virus transmission are a significant driving factor.^1-3 In the age of biologics, other options requiring fewer patient visits are available, such as UVB phototherapy. UV phototherapy is considered first line when more than 10% of the body surface area is affected.⁴ Although phototherapy often is performed in the office, it also may be delivered at home.² Home-based phototherapy is safe, effective, and similar in cost to office-based phototherapy.⁴ Currently, there are limited COVID-19–specific guidelines for home-based phototherapy.

The risks and sequelae of COVID-19 are still being investigated, with cases varying by location. As such, local and national public health recommendations are evolving. Dermatologists must make individualized decisions about practice services, as local restrictions differ. As office-based phototherapy services may struggle to implement mitigation strategies, home-based phototherapy is an increasingly viable treatment option.^1,4,5 Patient benefits of home therapy include improved treatment compliance; greater patient satisfaction; reduced travel/waiting time; and reduced long-term cost, including co-pays, depending on insurance coverage.^2,4

We aim to provide recommendations on home-based phototherapy during the pandemic. Throughout the decision-making process, careful consideration of safety, risks, benefits, and treatment options for physicians, staff, and patients will be vital to the successful implementation of home-based phototherapy. Our recommendations are based on maximizing benefits and minimizing risks.

Considerations for Physicians

Physicians should take the following steps when assessing if home phototherapy is an option for each patient.^1,2,4

• Determine patient eligibility for phototherapy treatment if currently not on phototherapy

• Carefully review patient and provider requirements for home phototherapy supplier

• Review patient history of treatment compliance

• Determine insurance coverage and consider exclusion criteria

• Review prior treatments

• Provide education on side effects

• Provide education on signs of adequate treatment response

• Indicate the type of UV light and unit on the prescription

• Consider whether the patient is in the maintenance or initiation phase when providing recommendations

• Work with the supplier if the light therapy unit is denied by submitting an appeal or prescribing a different unit

• Follow up with telemedicine to assess treatment effectiveness and monitor for adverse effects

Considerations for Patients

Counsel patients to weigh the risks and benefits of home phototherapy prescription and usage.^1,2,4

• Evaluate cost

• Carefully review patient and provider requirements for home phototherapy supplier

• Ensure a complete understanding of treatment schedule

• Properly utilize protective equipment (eg, genital shields for men, eye shields for all)

• Avoid sharing phototherapy units with household members

• Disinfect and maintain units

• Maintain proper ventilation of spaces

• Maintain treatment log

• Attend follow-up

Treatment Alternatives

For patients with severe psoriasis, there are alternative treatments to office and home phototherapy. Biologics, immunosuppressive therapies, and other treatment options may be considered on a case-by-case basis.^3,4,6 Currently, recommendations for the risk of COVID-19 with biologics or systemic immunosuppressive therapies remains inconsistent and should be carefully considered when providing alternative treatments.^7-11

Final Thoughts

As restrictions are lifted according to local public health measures, prepandemic office phototherapy practices may resume operations. Home phototherapy is a practical and effective alternative for treatment of psoriasis when access to the office setting is limited.

Office-based phototherapy practices have closed or are operating below capacity because of the coronavirus disease 2019 (COVID-19) pandemic.¹ Social distancing measures to reduce virus transmission are a significant driving factor.^1-3 In the age of biologics, other options requiring fewer patient visits are available, such as UVB phototherapy. UV phototherapy is considered first line when more than 10% of the body surface area is affected.⁴ Although phototherapy often is performed in the office, it also may be delivered at home.² Home-based phototherapy is safe, effective, and similar in cost to office-based phototherapy.⁴ Currently, there are limited COVID-19–specific guidelines for home-based phototherapy.

The risks and sequelae of COVID-19 are still being investigated, with cases varying by location. As such, local and national public health recommendations are evolving. Dermatologists must make individualized decisions about practice services, as local restrictions differ. As office-based phototherapy services may struggle to implement mitigation strategies, home-based phototherapy is an increasingly viable treatment option.^1,4,5 Patient benefits of home therapy include improved treatment compliance; greater patient satisfaction; reduced travel/waiting time; and reduced long-term cost, including co-pays, depending on insurance coverage.^2,4

We aim to provide recommendations on home-based phototherapy during the pandemic. Throughout the decision-making process, careful consideration of safety, risks, benefits, and treatment options for physicians, staff, and patients will be vital to the successful implementation of home-based phototherapy. Our recommendations are based on maximizing benefits and minimizing risks.

Considerations for Physicians

Physicians should take the following steps when assessing if home phototherapy is an option for each patient.^1,2,4

• Determine patient eligibility for phototherapy treatment if currently not on phototherapy

• Carefully review patient and provider requirements for home phototherapy supplier

• Review patient history of treatment compliance

• Determine insurance coverage and consider exclusion criteria

• Review prior treatments

• Provide education on side effects

• Provide education on signs of adequate treatment response

• Indicate the type of UV light and unit on the prescription

• Consider whether the patient is in the maintenance or initiation phase when providing recommendations

• Work with the supplier if the light therapy unit is denied by submitting an appeal or prescribing a different unit

• Follow up with telemedicine to assess treatment effectiveness and monitor for adverse effects

Considerations for Patients

Counsel patients to weigh the risks and benefits of home phototherapy prescription and usage.^1,2,4

• Evaluate cost

• Carefully review patient and provider requirements for home phototherapy supplier

• Ensure a complete understanding of treatment schedule

• Properly utilize protective equipment (eg, genital shields for men, eye shields for all)

• Avoid sharing phototherapy units with household members

• Disinfect and maintain units

• Maintain proper ventilation of spaces

• Maintain treatment log

• Attend follow-up

Treatment Alternatives

For patients with severe psoriasis, there are alternative treatments to office and home phototherapy. Biologics, immunosuppressive therapies, and other treatment options may be considered on a case-by-case basis.^3,4,6 Currently, recommendations for the risk of COVID-19 with biologics or systemic immunosuppressive therapies remains inconsistent and should be carefully considered when providing alternative treatments.^7-11

Final Thoughts

As restrictions are lifted according to local public health measures, prepandemic office phototherapy practices may resume operations. Home phototherapy is a practical and effective alternative for treatment of psoriasis when access to the office setting is limited.

The order Lepidoptera (phylum Arthropoda, class Hexapoda) is comprised of moths and butterflies.¹ Lepidopterism refers to a range of adverse medical conditions resulting from contact with these insects, typically during the caterpillar (larval) stage. It involves multiple pathologic mechanisms, including direct toxicity of venom and mechanical irritant effects.² Erucism has been defined as any reaction caused by contact with caterpillars or any reaction limited to the skin caused by contact with caterpillars, butterflies, or moths. Lepidopterism can mean any reaction to caterpillars or moths, referring only to reactions from contact with scales or hairs from adult moths or butterflies, or referring only to cases with systemic signs and symptoms (eg, rhinoconjunctival or asthmatic symptoms, angioedema and anaphylaxis, hemorrhagic diathesis) with or without cutaneous findings, resulting from contact with any lepidopteran source.¹ Strictly speaking, erucism should refer to any reaction from caterpillars and lepidopterism to reactions from moths or butterflies. Because reactions to both larval and adult lepidoptera can cause a variety of either cutaneous and/or systemic symptoms, classifying reactions into erucism or lepidopterism is only of academic interest.¹

We report a documented case of lepidopterism in a patient with acute cutaneous lesions following exposure to an adult-stage black butterfly (Hylesia nigricans).

Case Report

A 21-year-old oil well worker presented with pruritic skin lesions on the right arm and flank of 3 hours’ duration. He reported that a black butterfly had perched on his arm while he was working and left a considerable number of small yellowish hairs on the skin, after which an intense pruritus and skin lesions began to develop. He denied other associated symptoms. Physical examination revealed numerous 1- to 2-mm, nonconfluent, erythematous and edematous papules on the right forearm, arm (Figure 1A), and flank. Some abrasions of the skin due to scratching and crusting were noted (Figure 1B). A skin biopsy from the right arm showed a superficial perivascular dermatitis with a mixed infiltrate of polymorphonuclear predominance with eosinophils (Figure 2A). Importantly, a structure resembling an urticating spicule was identified in the stratum corneum (Figure 2B); spicules are located on the abdomen of arthropods and are associated with an inflammatory response in human skin.

Based on the patient’s history of butterfly exposure, clinical presentation of the lesions, and histopathologic findings demonstrating the presence of the spicules, the diagnosis of lepidopterism was confirmed. The patient was treated with oral antihistamines and topical steroids for 1 week with complete resolution of the lesions.

Comment

Epidemiology of Envenomation
Although many tropical insects carry infectious diseases, cutaneous injury can occur by other mechanisms, such as dermatitis caused by contact with the skin (erucism or lepidopterism). Caterpillar envenomation is common, but this phenomenon rarely has been studied due to few reported cases, which hinders a complete understanding of the problem.³

The order Lepidoptera comprises 2 suborders: Rhopalocera, with adult specimens that fly during the daytime (butterflies), and Heterocera, which are largely nocturnal (moths). The stages of development include egg, larva (caterpillar), pupa (chrysalis), and adult (imago), constituting a holometabolic life cycle.⁴ Adult butterflies and moths represent the reproductive stage of lepidoptera.

The pathology of lepidopterism is attributed to contact with fluids such as hemolymph and secretions from the spicules, with histamine being identified as the main causative component.³ During the reproductive stage, female insects approach light sources and release clouds of bristles from their abdomens that can penetrate human skin and cause an irritating dermatitis.⁵ Lepidopterism can occur following contact with bristles from insects of the Hylesia genus (Saturniidae family), such as in our patient.^3,6 Epidemic outbreaks have been reported in several countries, mainly Argentina, Brazil, and Venezuela.⁵ The patient was located in Colombia, a country without any reported cases of lepidopterism from the black butterfly (H nigricans). Cutaneous reactions to lepidoptera insects come in many forms, most commonly presenting as a mild stinging reaction with a papular eruption, pruritic urticarial papules and plaques, or scaly erythematous papules and plaques in exposed areas.⁷

Histopathologic Findings
The histology of lepidoptera exposure is nonspecific, typically demonstrating epidermal edema, superficial perivascular lymphocytic infiltrate, and eosinophils. Epidermal necrosis and vasculitis rarely are seen. Embedded spines from Hylesia insects have been described.⁷ The histopathologic examination generally reveals a foreign body reaction in addition to granulomas.³

Therapy
The use of oral antihistamines is indicated for the control of pruritus, and topical treatment with cold compresses, baths, and corticosteroid creams is recommended.^3,8,9

Conclusion

We report the case of a patient with lepidopterism, a rare entity confirmed histologically with documentation of a spicule in the stratum corneum in the patient’s biopsy. Changes due to urbanization and industrialization have a closer relationship with various animal species that are pathogenic to humans; therefore, we encourage dermatologists to be aware of these diseases.

The order Lepidoptera (phylum Arthropoda, class Hexapoda) is comprised of moths and butterflies.¹ Lepidopterism refers to a range of adverse medical conditions resulting from contact with these insects, typically during the caterpillar (larval) stage. It involves multiple pathologic mechanisms, including direct toxicity of venom and mechanical irritant effects.² Erucism has been defined as any reaction caused by contact with caterpillars or any reaction limited to the skin caused by contact with caterpillars, butterflies, or moths. Lepidopterism can mean any reaction to caterpillars or moths, referring only to reactions from contact with scales or hairs from adult moths or butterflies, or referring only to cases with systemic signs and symptoms (eg, rhinoconjunctival or asthmatic symptoms, angioedema and anaphylaxis, hemorrhagic diathesis) with or without cutaneous findings, resulting from contact with any lepidopteran source.¹ Strictly speaking, erucism should refer to any reaction from caterpillars and lepidopterism to reactions from moths or butterflies. Because reactions to both larval and adult lepidoptera can cause a variety of either cutaneous and/or systemic symptoms, classifying reactions into erucism or lepidopterism is only of academic interest.¹

We report a documented case of lepidopterism in a patient with acute cutaneous lesions following exposure to an adult-stage black butterfly (Hylesia nigricans).

Case Report

A 21-year-old oil well worker presented with pruritic skin lesions on the right arm and flank of 3 hours’ duration. He reported that a black butterfly had perched on his arm while he was working and left a considerable number of small yellowish hairs on the skin, after which an intense pruritus and skin lesions began to develop. He denied other associated symptoms. Physical examination revealed numerous 1- to 2-mm, nonconfluent, erythematous and edematous papules on the right forearm, arm (Figure 1A), and flank. Some abrasions of the skin due to scratching and crusting were noted (Figure 1B). A skin biopsy from the right arm showed a superficial perivascular dermatitis with a mixed infiltrate of polymorphonuclear predominance with eosinophils (Figure 2A). Importantly, a structure resembling an urticating spicule was identified in the stratum corneum (Figure 2B); spicules are located on the abdomen of arthropods and are associated with an inflammatory response in human skin.

Based on the patient’s history of butterfly exposure, clinical presentation of the lesions, and histopathologic findings demonstrating the presence of the spicules, the diagnosis of lepidopterism was confirmed. The patient was treated with oral antihistamines and topical steroids for 1 week with complete resolution of the lesions.

Comment

Epidemiology of Envenomation
Although many tropical insects carry infectious diseases, cutaneous injury can occur by other mechanisms, such as dermatitis caused by contact with the skin (erucism or lepidopterism). Caterpillar envenomation is common, but this phenomenon rarely has been studied due to few reported cases, which hinders a complete understanding of the problem.³

The order Lepidoptera comprises 2 suborders: Rhopalocera, with adult specimens that fly during the daytime (butterflies), and Heterocera, which are largely nocturnal (moths). The stages of development include egg, larva (caterpillar), pupa (chrysalis), and adult (imago), constituting a holometabolic life cycle.⁴ Adult butterflies and moths represent the reproductive stage of lepidoptera.

The pathology of lepidopterism is attributed to contact with fluids such as hemolymph and secretions from the spicules, with histamine being identified as the main causative component.³ During the reproductive stage, female insects approach light sources and release clouds of bristles from their abdomens that can penetrate human skin and cause an irritating dermatitis.⁵ Lepidopterism can occur following contact with bristles from insects of the Hylesia genus (Saturniidae family), such as in our patient.^3,6 Epidemic outbreaks have been reported in several countries, mainly Argentina, Brazil, and Venezuela.⁵ The patient was located in Colombia, a country without any reported cases of lepidopterism from the black butterfly (H nigricans). Cutaneous reactions to lepidoptera insects come in many forms, most commonly presenting as a mild stinging reaction with a papular eruption, pruritic urticarial papules and plaques, or scaly erythematous papules and plaques in exposed areas.⁷

Histopathologic Findings
The histology of lepidoptera exposure is nonspecific, typically demonstrating epidermal edema, superficial perivascular lymphocytic infiltrate, and eosinophils. Epidermal necrosis and vasculitis rarely are seen. Embedded spines from Hylesia insects have been described.⁷ The histopathologic examination generally reveals a foreign body reaction in addition to granulomas.³

Therapy
The use of oral antihistamines is indicated for the control of pruritus, and topical treatment with cold compresses, baths, and corticosteroid creams is recommended.^3,8,9

Conclusion

We report the case of a patient with lepidopterism, a rare entity confirmed histologically with documentation of a spicule in the stratum corneum in the patient’s biopsy. Changes due to urbanization and industrialization have a closer relationship with various animal species that are pathogenic to humans; therefore, we encourage dermatologists to be aware of these diseases.

The order Lepidoptera (phylum Arthropoda, class Hexapoda) is comprised of moths and butterflies.¹ Lepidopterism refers to a range of adverse medical conditions resulting from contact with these insects, typically during the caterpillar (larval) stage. It involves multiple pathologic mechanisms, including direct toxicity of venom and mechanical irritant effects.² Erucism has been defined as any reaction caused by contact with caterpillars or any reaction limited to the skin caused by contact with caterpillars, butterflies, or moths. Lepidopterism can mean any reaction to caterpillars or moths, referring only to reactions from contact with scales or hairs from adult moths or butterflies, or referring only to cases with systemic signs and symptoms (eg, rhinoconjunctival or asthmatic symptoms, angioedema and anaphylaxis, hemorrhagic diathesis) with or without cutaneous findings, resulting from contact with any lepidopteran source.¹ Strictly speaking, erucism should refer to any reaction from caterpillars and lepidopterism to reactions from moths or butterflies. Because reactions to both larval and adult lepidoptera can cause a variety of either cutaneous and/or systemic symptoms, classifying reactions into erucism or lepidopterism is only of academic interest.¹

We report a documented case of lepidopterism in a patient with acute cutaneous lesions following exposure to an adult-stage black butterfly (Hylesia nigricans).

Case Report

A 21-year-old oil well worker presented with pruritic skin lesions on the right arm and flank of 3 hours’ duration. He reported that a black butterfly had perched on his arm while he was working and left a considerable number of small yellowish hairs on the skin, after which an intense pruritus and skin lesions began to develop. He denied other associated symptoms. Physical examination revealed numerous 1- to 2-mm, nonconfluent, erythematous and edematous papules on the right forearm, arm (Figure 1A), and flank. Some abrasions of the skin due to scratching and crusting were noted (Figure 1B). A skin biopsy from the right arm showed a superficial perivascular dermatitis with a mixed infiltrate of polymorphonuclear predominance with eosinophils (Figure 2A). Importantly, a structure resembling an urticating spicule was identified in the stratum corneum (Figure 2B); spicules are located on the abdomen of arthropods and are associated with an inflammatory response in human skin.

Based on the patient’s history of butterfly exposure, clinical presentation of the lesions, and histopathologic findings demonstrating the presence of the spicules, the diagnosis of lepidopterism was confirmed. The patient was treated with oral antihistamines and topical steroids for 1 week with complete resolution of the lesions.

Comment

Epidemiology of Envenomation
Although many tropical insects carry infectious diseases, cutaneous injury can occur by other mechanisms, such as dermatitis caused by contact with the skin (erucism or lepidopterism). Caterpillar envenomation is common, but this phenomenon rarely has been studied due to few reported cases, which hinders a complete understanding of the problem.³

The order Lepidoptera comprises 2 suborders: Rhopalocera, with adult specimens that fly during the daytime (butterflies), and Heterocera, which are largely nocturnal (moths). The stages of development include egg, larva (caterpillar), pupa (chrysalis), and adult (imago), constituting a holometabolic life cycle.⁴ Adult butterflies and moths represent the reproductive stage of lepidoptera.

The pathology of lepidopterism is attributed to contact with fluids such as hemolymph and secretions from the spicules, with histamine being identified as the main causative component.³ During the reproductive stage, female insects approach light sources and release clouds of bristles from their abdomens that can penetrate human skin and cause an irritating dermatitis.⁵ Lepidopterism can occur following contact with bristles from insects of the Hylesia genus (Saturniidae family), such as in our patient.^3,6 Epidemic outbreaks have been reported in several countries, mainly Argentina, Brazil, and Venezuela.⁵ The patient was located in Colombia, a country without any reported cases of lepidopterism from the black butterfly (H nigricans). Cutaneous reactions to lepidoptera insects come in many forms, most commonly presenting as a mild stinging reaction with a papular eruption, pruritic urticarial papules and plaques, or scaly erythematous papules and plaques in exposed areas.⁷

Histopathologic Findings
The histology of lepidoptera exposure is nonspecific, typically demonstrating epidermal edema, superficial perivascular lymphocytic infiltrate, and eosinophils. Epidermal necrosis and vasculitis rarely are seen. Embedded spines from Hylesia insects have been described.⁷ The histopathologic examination generally reveals a foreign body reaction in addition to granulomas.³

Therapy
The use of oral antihistamines is indicated for the control of pruritus, and topical treatment with cold compresses, baths, and corticosteroid creams is recommended.^3,8,9

Conclusion

We report the case of a patient with lepidopterism, a rare entity confirmed histologically with documentation of a spicule in the stratum corneum in the patient’s biopsy. Changes due to urbanization and industrialization have a closer relationship with various animal species that are pathogenic to humans; therefore, we encourage dermatologists to be aware of these diseases.