▪ Recurrent migratory thrombophlebitis

▪ Unusual sites of thrombosis: axillary/subclavian veins; superficial veins of the neck, thorax, or abdomen; visceral or cerebral veins

▪ Failure to respond clinically to warfarin

▪ Usually respond clinically to heparin but may relapse immediately after discontinuation

▪ May appear to be “heparin resistant” because of rapid consumption of heparin

▪ May simultaneously experience arterial thrombosis and hemorrhage

▪ Associated with nonbacterial thrombotic endocarditis

▪ Tumor often small or occult adenocarcinoma

▪ No laboratory test sensitive or specific

▪ A shortened PTT may be encountered in some cases

▪ Platelets and antithrombin III levels are usually decreased

▪ Red blood cells may show changes consistent with microangiopathic hemolysis