Am J Dermatopathol. 2020 Nov 3. doi: 10.1097/DAD.0000000000001829. Online ahead of print.
Biopsies were taken from 4 patients who presented to their dermatologist with violaceous papules and plaques of the dorsal toes (COVID Toes) associated with varying degrees of severe acute respiratory syndrome coronavirus 2 exposure and COVID-19 testing. Major histopathologic findings were lymphocytic eccrine inflammation and a spectrum of vasculopathic findings to include superficial and deep angiocentric-perivascular lymphocytic inflammation, lymphocytes in vessel walls (lymphocytic vasculitis), endothelial swelling, red blood cell extravasation, and focal deposits of fibrin in both vessel lumina, and vessel walls. Interface changes were observed to include vacuolopathy and apoptotic keratinocytes at the basement membrane. Immunostains showed a dominant T-cell lineage (positive for T-cell receptor beta, CD2, CD3, CD5, and CD7). B-cells were rare and clusters of CD123-positive dermal plasmacytoid dendritic cells were observed surrounding eccrine clusters and some perivascular zones. The consistent perieccrine and vasculopathic features represent important pathologic findings in the diagnosis of COVID toes and are suggestive of pathogenetic mechanisms. Clinicopathologic correlation, the epidemiological backdrop, and the current worldwide COVID-19 pandemic favor a viral causation and should alert the physician to initiate a workup and the appropriate use of COVID-19 testing.