Quinidine-induced thrombocytopenia with pulmonary hemorrhage.

Examination of an elderly man with quinidine sulfate-induced thrombocytopenia complicated by pulmonary hemorrhage failed to identify any underlying pulmonary disease contributing to the bleeding All bleeding ceased, and pulmonary infiltrates disappeared after the platelet count returned to normal. Special studies indicated a high titer quinidine-dependent IgG antibody level in the patient's serum and a strongly positive quinidine patch test result on his forearm. The pathogenesis of pulmonary hemorrhage is considered in view of these studies.