key: cord-0912206-zks1i18c
authors: Le Cleach, L
title: Dermatology and Covid-19: much knowledge to date but still a lot to discover
date: 2021-03-12
journal: Ann Dermatol Venereol
DOI: 10.1016/j.annder.2021.03.001
sha: b6f8ac2d75f67f504dbef7db384f5a07c5dc55bb
doc_id: 912206
cord_uid: zks1i18c

nan

J o u r n a l P r e -p r o o f Acral manifestations, mainly chilblains, are the topics that gave rise to the greatest number of publications. More than 2000 cases have been reported, taking into account only series including more than 10 patients [6] .

Patients with manifestations other than chilblains had a mean age of between 40 and 50 years and overall, hospitalization for COVID-19 was required in one third of them. Patients presenting with chilblains were distinguished by their age (most often children or young adults), and absence of infectious signs or presence of only slight infectious signs.

Questions remain regarding the link between skin manifestations and SARS-CoV-2. Considering the different types of exanthema reported, no specific type as for measles or chickenpox for example seems to emerge for COVID-19. A link between different types of non-specific exanthema and the virus is thus more difficult to establish. In addition, the retrospective designs of the largest studies often preclude the possibility of excluding differential diagnosis for the cutaneous manifestations observed such as adverse drug reactions regarding maculopapular exanthema. For a large proportion of reported patients with cutaneous manifestations possibly related to COVID-19, the diagnosis of COVID-19 remains unsure due to the lack of available laboratory tests to confirm diagnosis [3, 4] .

Chilblains in particular have led to much debate about association with COVID19 because of the absence or mildness of infectious signs, as well as negative PCR and/or serological results in 90% of cases. One hypothesis put forward is a marked type I interferon response that could account for the occurrence of chilblains by analogy with those observed in type I interferonopathies as well as SARS-CoV-2 clearance before the occurrence of humoral immunity development [7] . Other authors have favoured the hypothesis of the role of inactivity during lockdown and a snowball effect following media announcements of a link between chilblains and COVID-19 [8] . 

Another important question in daily practice was to determine whether patients treated for chronic inflammatory dermatoses using immunomodulating treatments are at higher risk of severe form of the disease. Data collected to date via international registries concerning systemic treatments for psoriasis are reassuring [10] . These data have led the European Dermatology Forum and the American Academy of Dermatology to advise against interrupting treatments except as a precautionary measure in the event of COVID infection. However, data for other immunosuppressants including rituximab in a registry of rheumatological diseases seems less reassuring [11] . Data collected so far concerns systemic treatments. In this issue, Souaid et al. raise the question of the risk associated with application of topical immunosuppressive treatments [12] .

The team reported that neither the frequency of contamination nor the severity of the infection appeared to increase in patients treated for at least 4 weeks with topical corticosteroids and/or topical tacrolimus, either alone or in combination with systemic treatments.

Although the data concerning the specific risk of chronic inflammatory skin diseases or treatments are reassuring, the pandemic has nevertheless had an impact on patients presenting chronic illnesses Never has such an amount of data has been accumulated in so short a period of time thanks to enormous international mobilization of the dermatological community. The 5 studies presented in this issue contribute to the effort. Unanswered questions and uncertainties remain; however, the

Centre of Evidence Based Dermatology. CEBD Coronavirus Dermatology Resource

Cutaneous manifestations in SARS-CoV-2 infection (COVID-19): a French experience and a systematic review of the literature

Classification of the cutaneous manifestations of COVID-19: a rapid prospective nationwide consensus study in Spain with 375 cases

The spectrum of COVID-19-associated dermatologic manifestations: An international registry of 716 patients from 31 countries

Cutaneous manifestations of COVID-19 in Franche-Comté (France): a monocentric study

Most chilblains observed during the COVID-19 outbreak occur in patients who are negative for COVID-19 on polymerase chain reaction and serology testing

Clinical, laboratory, and interferon-alpha response characteristics of patients with chilblain-like lesions during the COVID-19 pandemic

Emerging evidence of the direct association between COVID-19 and chilblains-Reply

Acute acral eruptions in children during the COVID-19 pandemic: characteristics of 103 children and their family clusters

Factors associated with adverse COVID-19 outcomes in patients with psoriasis-insights from a global registry-based study

Factors associated with COVID-19-related death in people with rheumatic diseases: results from the COVID-19 Global Rheumatology Alliance physician-reported registry

Topical steroids and topical tacrolimus appear safe regarding the COVID-19 epidemic

Impact of the COVID-19 pandemic on children with psoriasis

Psychological and professional impact of COVID-19 lockdown on French dermatologists: Data from a large survey