Chilblains (COVID toes) are being seen with increasing frequency in children and young adults during the COVID-19 pandemic. Detailed histopathological descriptions of COVID-19 chilblains have not been reported, and causality of SARS-CoV-2 has not yet been established.

A new study published in The British Journal of Dermatology aimed to describe the histopathological features of COVID-19 chilblains and to explore the presence of SARS-CoV-2 in the tissue.

In this histopathological, immunohistochemical and ultrastructural study, skin biopsies from seven pediatric patients presenting with chilblains were examined, during the COVID-19 pandemic.

Histopathological results showed variable degrees of lymphocytic vasculitis ranging from endothelial swelling and endotheliitis to fibrinoid necrosis and thrombosis. Additionally, purpura, superficial and deep perivascular lymphocytic inflammation with perieccrine accentuation, oedema and mild vacuolar interface damage were noted. SARS-CoV-2 immunohistochemistry was positive in endothelial cells and epithelial cells of eccrine glands. While coronavirus particles were found in the cytoplasm of endothelial cells on electron microscopy.

In inference, it was stated that although the clinical and histopathological features were similar to other forms of chilblains, the presence of viral particles in the endothelium and the histological evidence of vascular damage support a causal relation of the lesions with SARS-CoV-2. The researchers proposed that endothelial damage induced by the virus could be the key mechanism in the pathogenesis of COVID-19 chilblains and perhaps also in a group of patients severely affected by COVID-19 presenting with features of microangiopathic damage.

Source: The British Journal of Dermatology.2020 Jun 20;10.1111/bjd.19327.doi: 10.1111/bjd.19327.