Procainamide-induced systemic lupus erythematosus. Renal involvement with deposition of immune complexes.

A 54-year-old man sustained an acute anterior myocardial infarction and was subsequently treated with procainamide hydrochloride for 5 1/2 months, resulting in development of a drug-induced systemic lupus erythematosus (SLE) syndrome with renal involvement. In over 60 reported cases of procainamide-induced SLE, clinical renal evaluation has led to the concept that renal involvement is a rarity in this disease. Direct immunofluorescence examination of necropsy kidney tissue revealed mesangial deposition of immunoproteins and C3 in a granular pattern characteristically seen in idiopathic SLE. Ultrastructural studies confirm mesangial deposition of immune complexes. The immunological and ultrastructural pattern of immune complex deposition in glomeruli suggests similar pathological mechanisms for glomerular injury in procainamide as seen in idiopathic SLE.