oronavirus disease 2019 (COVID-19) is mainly characterized by fever and respiratory symptoms. 1 During this pandemic, several cases of unusual purplish red lesions on the feet and/or hands, mimicking chilblains, have been reported in the literature and on social media. Some researchers have suspected that these lesions are associated with asymptomatic or mildly symptomatic COVID-19. 2-7 However, to our knowledge, no study has proved a pathologic link between these skin lesions and COVID-19. This observational prospective case series aimed to investigate the possible association between chilblains and COVID-19. Methods Between April 10 and April 17, 2020, we enrolled 31 patients who visited the Department of Dermatology at Cliniques uni-versitaires Saint-Luc, Brussels, Belgium. All patients had purplish red chilblain lesions on toes and/or fingers, which had appeared between 1 and 30 days before consultation. The data from all study participants are summarized in the Table. The study and data collection were approved by the institutional review boards of Cliniques universitaires Saint-Luc and Université Catholique de Louvain. Written informed consent was obtained from all study participants. All patients underwent reverse transcriptase-polymerase chain reaction (RT-PCR) analysis by nasopharyngeal swab to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA when they presented for chilblains. In all patients, blood analyses included the following: liver function and renal function; tests for antinuclear antibodies, rheumatoid factor, CH50, C3, C4, antineutrophil cytoplasmic autoantibody, antistreptolysin O antibody, and cold agglutinins; prothrombin time and activate partial thromboplastin time; levels of D-dimer, an-IMPORTANCE During the coronavirus disease 2019 (COVID-19) pandemic, several cases of chilblains have been reported. OBJECTIVE To determine if chilblains are associated with COVID-19. DESIGN, SETTING, AND PARTICIPANTS This monocentric case series was conducted at the Department of Dermatology at Cliniques universitaires Saint-Luc, a tertiary care hospital in Brussels, Belgium, between April 10 and April 17, 2020. We evaluated a total of 31 referred patients who had recently developed chilblains. MAIN OUTCOMES AND MEASURES Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on nasopharyngeal swabs for all patients and in skin biopsy specimens for 22 patients. Blood samples from all patients were tested for specific anti-SARS-CoV-2 immunoglobulin (Ig) M and IgG antibodies. All patients had extended blood analyses. Histologic (22 patients) and immunofluorescence examinations (15 patients) were performed on the skin biopsy specimens. RESULTS The 31 patients were generally in good health; most were teenagers or young adults, and 19 were women. Histopathologic analysis of skin biopsy specimens (22 patients) confirmed the diagnosis of chilblains and showed occasional lymphocytic or microthrombo...

This study showed that, in allergic contact dermatitis caused by corticosteroids, the inflammatory infiltrate is composed of CD3(+) T cells with a predominant Th2 cytokine profile, among which IL-4 is also produced by γδ TCR lymphocytes.

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