Abstract
A boy one year and ten-months old was diagnosed as having acute megakaryoblastic leukemia. Prolongation of prothrombin time (PT) and activated partial thromboplastin time (APTT), antidouble-strand DNA antibody, and biologically false positive serologic tests for syphilis (BFP-STS) were also noted, and close examination demonstrated the presence of lupus anticoagulant (LA). By the 7th day of chemotherapy, PT and APTT had changed toward normal, and BFP-STS became negative. On the 41st day, when the bone marrow showed complete remission, PT and APTT were normalized with the disappearance of LA. No episodes of thrombosis were observed in the entire course of the patient. Antiphospholipid antibodies (APAs) associated with the onset of several hematological malignancies have been reported, and they are responsible for the occurrence of thrombosis, but in a limit of cases positive for LA. As shown in the present case and previous reports, APAs detected at the onset of hematological malignancies become negative along with the regression and disappearance of tumors, and do not enhance the risk of thrombosis thereafter. Thus no prophylaxis of thrombosis is required except for cases showing resistance to chemotherapy.
