Clinical and morphological correlations in acute promyelocytic leukemia

Thirty adults with acute leukemia and greater than 20% bone marrow infiltrate by promyelocytes were studied. Eighteen patients had acute promyelocytic leukemia (APML) as defined by the presence of malignant promyelocytes, and the remaining 12 patients had acute myelocytic leukemia (AML) with an elevated percentage of normal promyelocytes. Malignant promyelocytes were characterized by abundant, abnormal, cytoplasmic granules, by Auer rods in meshwork pattern, and by splinter cytoplasmic granulations and dilatation of the cisternae of endoplasmic reticulum. Patients with APML had, in general, greater than 35% bone marrow infiltrate by promyelocytes. The degree of bone marrow infiltrate by these cells correlated with the clinical status of the patients. Diffuse intravascular coagulation with bleeding occurred in 61% of patients with APML, and the bone marrows of these patients had greater than 50% promyelocytes. No coagulation abnormalities were seen among patients with elevated bone marrow promyelocytes infiltrate and without APML. Coagulation abnormalities in patients with APML were only corrected by controlling the leukemia itself. When this occurred, patients with APML had an excellent rate of complete remission, and the duration of remission and survival were comparable to the results obtained in adults with AML.