Within a few weeks, COVID-19 has transformed our lives, medical practices and global networks in frightening and devastating ways. Yet at the same time, it has been remarkable to observe how the scientific community is working together at almost lightning speed to acquire and disseminate knowledge on the virus. Our understanding of the virus is expanding daily thanks to this collective effort.
Dermatologists across the world have been actively documenting cutaneous manifestations in patients with COVID-19. One of the first studies emerged from Italy in March. They followed 88 hospitalized patients with COVID-19 and found that 20% developed skin findings. The dermatologic findings included an erythematous rash, urticaria and chickenpox-like vesicles. Skin lesions were mostly truncal, associated with minimal pruritus and did not seem to correlate with disease severity.1
In the United States, dermatologists seeing critically ill patients with acute respiratory failure in New York City reported skin changes consistent with hypercoagulable states. They observed retiform purpura, nonblanching violaceous stellate patches, and livedo racemosa, broken vascular networks, on the extremities. Pathology specimens of both the lung and skin were examined, and both showed a pauci-inflammatory thrombogenic vasculopathy with deposition of terminal complement components (C5b-C9). The authors hypothesize that at least a subset of severe COVID-19 infection results in catastrophic microvascular injury mediated by complement activation.2 Further studies are needed, but skin tissue, more readily accessible than lung, may be able to provide information on the pathological mechanisms of the virus and perhaps help predict which patients are at risk for hypercoagulable side effects.
More recently, reports have emerged of chilblains in young adults with COVID-19. Chilblains, or perniosis, refers to tender, or occasionally itchy, violaceous plaques on acral surfaces. It typically occurs during cold and damp seasons as a result of small vessel constriction. The condition usually self-resolves but then may recur each year. There seems to have been an increase in cases of chilblains during the last few months in patients with no prior history of these findings, prompting clinicians to suspect an association with COVID-19 and coin the term, “COVID toes.” It is still unclear whether the chilblains findings represent acute infection or an immunological response to a past infection. Currently, many clinicians are obtaining both viral PCR and serologies on these patients. Of course, some people may simply be developing chilblains as a response to an unseasonably cool and damp month of April.
Although much more research is needed, many of the patients with chilblains and COVID-19 are children and young adults who have a mild course of respiratory symptoms or develop these findings after a completely asymptomatic infection. Pathology of a pernio-like skin lesion in a patient with COVID-19 showed perivascular inflammation but no intraluminal thrombi.3 It will be interesting to see if further evaluation reveals a different response to the virus in these patients who seem to have an otherwise relatively mild disease course.
With now more than 3 million cases of the virus worldwide, it is unlikely that there is a dermatologic rash specific to COVID-19. It probably would have been identified by now. However, the skin is certainly affected in patients with the virus and may be able to help us further understand its pathology. The findings to date seem to fall in two major pathomechanisms: (1) viral exanthems (i.e., non-specific morbilliform rash) as a result of an immune response to viral nucleotides and (2) cutaneous eruptions secondary to systemic consequences of COVID-19, vasculitis or thrombotic vasculopathy. Additionally, it is important to note that patients with viral infections are at higher risk of adverse drug reactions. Therefore, particularly in hospitalized patients on multiple medications who develop new cutaneous signs, a drug rash should always be considered.4
As we continue to learn more about the skin and COVID-19, we should hope to uncover (1) if there are any skin findings that could suggest current or past infection (2) if there are any skin signs helpful in the acute management of patients (3) if cutaneous manifestations could enrich our understanding of the pathophysiology of the virus.5
The American Academy of Dermatology (AAD) COVID-19 Task Force has launched an online registry to rapidly collect information on the cutaneous manifestations of COVID-19 (www.aad.org/covidregistry). Cases can be entered by any healthcare professional within minutes and do not require patient protected health information. By allowing the global community to share observations, the hope is ultimately to better understand the dermatologic manifestations of the virus and their potential implications, if any, on patient outcomes. Please consider contributing your cases to this registry as we all work to learn from each other.
Recalcati S. Cutaneous manifestations in COVID-19: A first perspective. J Eur Acad Dermatol Venereol 2020; Mar 26. doi: 10.1111/jdv.16387. [Epub ahead of print]
Magro C, Mulvey JJ, Berlin D, et al. Complement associated microvascular injury and thrombosis in the pathogenesis of severe COVID-19 infection: A report of five cases. Transl Res. 2020;S1931-5244(20)30070-0. doi:10.1016/j.trsl.2020.04.007. [Epub ahead of print]
Kolivras A, Dehavay F, Delplace D, et al. Coronavirus (COVID-19) infection-induced chilblains: A case report with histopathologic findings. JAAD Case Reports 2020; doi.org/10.1016/j.jdcr.2020.04.011 [Article in press]
Suchonwanit P, Leerunyakul K, Kositkuljorn C. Cutaneous manifestations in COVID-19: Lessons learned from current evidence. J Am Acad of Dermatol 2020; April 24. doi.org/10.1016/j.jaad.2020.04.094. [Epub ahead of print]
Rosenbach, M. COVID-19, “COVID toes,” and clinical manifestations. Dermatology World. Vol 2. No. 16. https://www.aad.org/dw/dw-insights-and-inquiries/2020-archive/april/dermatological-manifestations-covid-19-part-4