Clinical and cytogenetic correlations of abnormal megakaryocytopoiesis in patients with acute leukemia and chronic myelogenous leukemia in blast crisis

It has been suggested that abnormalities of chromosome 3 at bands q21 and q26 are associated with the presence of increased numbers of abnormal megakaryocytes in patients with hematologic malignancies. The pretreatment bone marrows of 287 patients with leukemia (acute myeloid leukemia (AML), 225 patients; acute lymphocytic leukemia (ALL), 36 patients; or chronic myelogenous leukemia in blast crisis (CML-B), 26 patients) were reviewed to identify those with normal or increased numbers of megakaryocytes. Thirty-two patients with AML, one with ALL, and 10 with CML-B had normal or increased numbers of megakaryocytes. Of the 32 patients with AML, 19 patients had significant numbers of mononuclear or binuclear small megakaryocytes as well as megakaryocytes with separated nuclei ("micromegakaryocytes"). Cytogenetic analyses were obtained in 29 of 32 patients with AML and showed inv(3)(q21q26) (one patient); Ph1 (two patients); -5 and/or -7 (seven patients); normal karyotypes (10 patients). No patient with micromegakaryocytes had a chromosomal abnormality associated with a favorable prognosis. Overall, among 225 patients with AML, four had inv(3)(q21q26) or t(3;3)(q21;q26). Only one of these four patients had normal or increased numbers of megakaryocytes, although all four had micromegakaryocytes. One patient with CML-B had inv(3)(q21q26) but had decreased numbers of megakaryocytes and a platelet count of 24 x 10(3)/microliters. All five patients with abnormal chromosome 3 at bands q21 and q26 had additional cytogenetic abnormalities (Ph1 in two patients; -7 in three patients). Mean and median platelet counts were greater than 100,000/microliters for patients with marrow megakaryocytosis regardless of morphology, as well as for the patients with abnormalities involving 3q21 and 3q26. Abnormalities of megakaryocyte morphology, increases in the numbers of megakaryocytes, and normal to increased platelet counts are not uncommon in patients with acute leukemia and CML-B, and are not uniquely associated with changes involving chromosome 3.