Chilblain
Idiopathic chilblain or also called acro-ischemic lesions, presenting as violaceous, infiltrated painful and sometimes even pruritic plaques on erythematous skin with predilection on the back of the toes or feet has been described to occur in a special group of SARS-CoV-2 positive, suspected patients as well as asymptomatic or non-infected patients (Fig. 4F) (66, 67 ). Histologic features of these lesions were typical for a lymphocytic vasculitis, with a superficial and deeper lymphocytic infiltration around vessels and close to eccrine glands, a papillary edema, vacuolar degeneration of the basal layer as well as lymphocytic exocytosis to the epidermis. Red cell extravasation as well as focal thrombosis in papillary dermal capillaries as well as vessels of the reticular dermis were described in some reports as well (49, 68 ). The pathologic pathways behind these lesions are still unknown and remain to be elucidated. If it is related to SARS-Cov-2 infection remains to be demonstrated.