key: cord-0932929-kihezdgg
authors: Capalbo, Alessandro; Giordano, Domenico; Gagliostro, Nazareno; Balampanos, Charalampos Georgios; Persechino, Flavia; Orrù, Federica; Persechino, Severino
title: Alopecia areata in a COVID‐19 patient: A case report
date: 2021-01-12
journal: Dermatol Ther
DOI: 10.1111/dth.14685
sha: efb528063028d05f48af6422f67c1fba9096b3fc
doc_id: 932929
cord_uid: kihezdgg

nan

Only few cases of AA in SARS-CoV-2-infected patients have been reported in the literature. 3 The interplay among genetic factors (ie, HLA-DR, CTLA4 and ULBP3) and environmental factors (ie, emotional/physical stress, hormones and infections) has been shown to play a key role in the AA etiology and progression. 4, 5 Although the exact pathophysiology remains unknown, it seems to be related to an autoimmune reaction against the hair follicles.

Supporting the autoimmune genesis of AA, several studies refer its association with other autoimmune diseases, such as type I diabetes and vitiligo. 4 We assume that SARS-CoV-2 could be an additional risk factor in the pathogenesis of AA. Referring to this, viral infection seems to be involved in autoimmune pathogenesis by two mechanisms: According to bystander theory, the presence of pathogens increases the release of costimulatory signals allowing the dendritic cells to present antigens more effectively, both pathogen and selfantigens. If this occurs in genetically predisposed individuals, the activation of self-reactive T lymphocytes could develop and progress ( Figure 4 ).

As stated in the molecular mimicry theory, the virus could have antigens which cross-react with self-antigens, so that the immune response turns against host tissues. 6 Moreover, considering the significant impact of COVID-19 pandemic on mental health, psychological stress appears to be another possible risk factor of AA. 5, 7 SARS-CoV-2 could act as a trigger in different autoimmune pathways, by creating an inflammatory environment which allows the nonspecific activation of the immune system or by a cross-reaction between its antigens and host antigens.

F I G U R E 1 Pictures showing round bold patches variously distributed on the beard area

Pictures showing trichoscopic findings of Alopecia Areata of the beard: black dots, yellow dots, broken hairs, vellus hairs F I G U R E 3 Pictures showing an improvement of the old lesions and the appearance of new ones, after two weeks of treatment with a trichological lotion with nicotinic acid, resorcinol and hyaluronic acid

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