Heparin-induced thrombocytopenia type II: a rare but significant complication of plasma exchange.

Type II heparin-induced thrombocytopenia (HIT) is a rare but well-recognised and potentially life-threatening complication of unfractionated heparin therapy, and has been reported in association with heparin locks for central venous lines. We report a case of type II HIT complicated by iliofemoral deep venous thrombosis and pulmonary embolism in a 43-year-old woman in the course of plasma exchange for myasthenia gravis. A Gamcath central venous line had been inserted femorally due to poor peripheral venous access, and this was locked with heparin 5000 U/ml between procedures. Twelve days after initial heparin exposure, she presented with new-onset thrombocytopenia, a painfully swollen right leg, and pleuritic pain. Deep venous thrombosis and pulmonary embolism were confirmed radiologically, and serology for heparin/PF4 antibodies was unequivocally positive. The line was removed, and she was successfully managed with intravenous lepirudin, switching to warfarin on platelet recovery. This case demonstrates that Type II HIT can occur in association with heparin line locks in the course of plasmapheresis, despite previous reports of successful use of plasma exchange to treat Type II HIT.