Abstract
1. Two patients with acute promyelocytic leukemia (APL) are reported. Many of the promyelocytes were atypical. Of the 57 patients with this disorder in the literature, only three survived more than 4 months. Our patients underwent complete remission on 6-mercaptopurine, and survived 8 and 14 months, respectively.
2. Coagulation abnormalities in these two patients were thrombocytopenia; fibrinogen and factor V deficiencies; and, in one, prothrombin deficiency. These defects disappeared with remission, then reappeared terminally. In contrast to most previous reports, no increased fibrinolytic activity was found in their blood. Infused fibrinogen disappeared abnormally rapidly from the blood of one patient; this was not affected by simultaneous heparin administration, and no thrombi were seen at autopsy.
3. Fibrinogen, factor V, and prothrombin were assayed in 86 patients with other forms of leukemia before treatment or in relapse. Fibrinogen deficiency was found in none; prothrombin and/or factor V deficiency in eight. Three of these had acute myeloblastic, three acute myelomonoblastic, and two chronic myelocytic leukemia.
4. The characteristic cellular morphology, combined with the usual finding of fibrinogen and factor V deficiencies, makes for a distinct differentiation of APL from other forms of leukemia.
