Propylthio-uracil-induced cutaneous vasculitis.

Three cases of cutaneous vasculitis, leukocytopenia and arthralgia, presumably caused by the antithyroid drug Propylthio-uracil, are presented. Acute vasculitis of the superficial and deep dermal blood vessels accompanied by vascular thrombus formation were found in biopsy specimens. Direct immunofluorescence studies demonstrated deposits of C3 or IgM and C3 in the walls of vessels in affected and unaffected skin, suggesting immune complex deposition. The skin lesions and leukocytopenia rapidly disappeared on discontinuation of the drug, while the arthralgia continued for weeks or months.