Circulating anticoagulant in the procainamide-induced lupus syndrome.

An elderly man with procainamide hydrochloride-induced lupus syndrome had a circulating anticoagulant against factor XI and a biologic false-positive (BFP) test result for syphilis. This was not associated with hemorrhagic problems. The activity of the circulating anticoagulant and the BFP disappeared within days following discontinuation of procainamide and the administration of corticosteroids.