Evaluation of Chilblains as a Manifestation of the COVID-19 Pandemic

This case series describes 31 patients, most of them teenagers or young adults, who presented with chilblains during the COVID-19 pandemic. Question Is there an association between chilblains and coronavirus disease 2019 (COVID-19)? Findings In this case series of 31 patients who had recently developed chilblains, none of the patients tested positive for COVID-19 on nasopharyngeal swabs, nor were blood immunoglobulin (Ig) M or IgG antibodies detected. Meaning These ischemic, acral cutaneous lesions appeared not to be directly associated with COVID-19. 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 microthrombotic phenomena. Immunofluorescence analyses showed vasculitis of small-diameter vessels in 7 patients. In all patients, SARS-CoV-2 RNA remained undetected by RT-PCR on nasopharyngeal swabs and in biopsy samples of the skin lesions. The IgM and IgG antibody titers were negative for SARS-CoV-2 in all patients (<1.0 arbitrary unit/mL). No significant abnormalities in blood test results were suggestive of systemic disease. Antinuclear antibody titers were low in 7 patients and higher in 1 patient. Conclusions and Relevance Chilblains appeared not to be directly associated with COVID-19 in this case series. Lifestyle changes associated with community containment and lockdown measures are a possible explanation for these lesions.