Histopathological features of Chilblain-like lesions developing in the setting of the COVID-19 pandemic

Context: During the coronavirus disease 2019 pandemic, several studies have described a distinctive cutaneous manifestation with a clinical picture resembling chilblains or chilblain lupus in young patients. Objective: To report the histopathological description of a series of chilblain-like lesions appearing in the context of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic. Design: The study included 13 patients with cutaneous acral lesions resembling chilblains occurring in the setting of suspected SARS-CoV-2 infection with available skin biopsy. Results: Two main histopathological patterns were observed: a chilblain-like histopathological pattern (10 cases out of 13, 77%) and a thrombotic vasculopathy pattern (3 cases out of 13, 23% of cases). The chilblain-like histopathological pattern featured a superficial and deep perivascular infiltrate of lymphocytes of varying intensity. This infiltrate was sometimes peri-eccrine and alterations of eccrine glands were present in most cases. Vacuolar alteration of the basal layer of the epidermis was found in a majority of patients. Lichenoid interface dermatitis was rarely present. The thrombotic vasculopathy pattern featured an absent or mild inflammatory infiltrate, multiple intraluminal fibrin thrombi and ischemic epidermal necrosis. In both patterns, no true vasculitis was observed. No patient was tested positive for SARS-CoV-2 by polymerase chain reaction possibly due to the fact that these lesions may represent late cutaneous manifestations of the disease or are associated with an early effective immune response. Conclusion: The relationship of chilblain-like lesions to SARS-CoV-2 requires further investigations. Histopathological features mimic chilblains, chilblain lupus and less frequently a thrombotic vasculopathy. Response to viral infection might trigger diverse mechanisms leading to the two histopathological patterns described.