Fig. 12.

Cutaneous eruptions reflective of an Arthus type III immune response to SARS-COV-2 signifying an effectual B-cell response. (A) The patient was a man aged 72 years who had lethargy, fever, and shortness of breath The patient also developed palpable purpura. The patient was found to be SARS-CoV-2 positive. A biopsy was performed of his skin eruption, which demonstrated a lymphocytic and neutrophil-enriched necrotizing vasculitis. The biopsy specimen showed a vasocentric lymphocytic and neutrophilic infiltrate that surrounds and permeates the vessel wall with evidence of vascular compromise characterized by mural fibrin deposition with attendant hemorrhage. (hematoxylin and eosin, 100 ×). (B), (C) The higher power magnification demonstrates an angiocentric and interstitial mixed infiltrate comprising lymphocytes, monocytes, and neutrophils. There is prominent endothelial cell swelling and there is prominent red cell extravasation corroborative of the diagnosis of a mixed leukocytoclastic and lymphocytic vasculitis (hematoxylin and eosin, 400 ×). SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.