[Paraneoplastic syndrome hematologic abnormalities].

The paraneoplastic syndrome (PNS) is an association of symptoms and signs not directly related to the site or local manifestations of a malignant tumor or its metastases. Hematologic abnormalities as PNS include erythrocytosis, anemia, neutrophilia, neutropenia, eosinophilia, thrombocytosis, thrombocytopenia, venous thromboembolism and disseminated intravascular coagulation (DIC). These abnormalities are, by and large, due to the production of biologically active growth factors, hormones or as yet unidentified "humors" by the tumor. As our understanding of growth factors controlling hematopoiesis has increased in recent years, the biologic basis of hematologic PNS are better understood. For instance, tumor-associated neutrophilia is now known to be caused by the production of G-CSF by the tumor. The mechanism by which tumor causes thromboembolism have also been extensively investigated. Cancer cells induce platelet aggregation both in vitro and in vivo. Platelet aggregating material has been isolated and partially characterized from tumor cells. The involvement of platelet glycoprotein II b/IIIa in the tumor-platelet interaction has also been shown. Malignant cells contain a unique procoagulant, cancer procoagulant A, that directly activates factor X. Together with tissue factor, this procoagulant appears to have been contribute to a high incidence of thromboembolism in cancer patients. Better understanding of hematologic PNS is important for clinical care of the patients with cancer.