Delayed-onset heparin-induced thrombocytopenia. A potentially malignant syndrome

Delayed-onset thrombocytopenia developed in 12 patients while they were receiving either prophylactic or therapeutic heparin. Five of the patients had thrombocytopenia alone, and seven had thromboembolic complications which contributed to the death of one patient. These complications included deep venous thrombosis (four patients), pulmonary embolism (three patients), myocardial infarction (one patient), sagittal sinus thrombosis (one patient), and femoral artery occlusion (one patient). The diagnosis of heparin-induced thrombocytopenia was delayed for between one and 13 days after the initial complicating event. All patients had heparin-dependent platelet-aggregating factor in their plasma. The characteristics of the heparin-dependent platelet-aggregating reaction were the same in all patients, but the nadir of thrombocytopenia was lower in patients with delayed-onset heparin-induced thrombocytopenia and complicating thromboembolism. These findings highlight the necessity for early recognition of this syndrome and for the prompt withdrawal of heparin to prevent considerable patient morbidity.

A case of Hageman factor deficiency with myeloid leukaemia

The co-existence of blastic transformation of chronic myeloid leukaemia and an isolated deficiency of coagulation factor XII (Hageman Factor), is reported. In the absence of any evidence of factor XII deficiency in the patient's siblings and children, it is uncertain if this represents an acquired factor XII deficiency due to myeloid leukaemia, or the coincidental occurrence of myeloid leukaemia with this autosomal recessive condition.