Blastic transformation of essential thrombocythemia: dual expression of
myelomonoblastic/megakaryoblastic phenotypes
D Frei-Lahr, JC Barton, R Hoffman, LL Burkett and JT Prchal
Three patients developed blastic transformation of essential
thrombocythemia (tET). Morphological studies in all patients showed that
the majority of blasts had either myeloblastic or myelomonoblastic
differentiation. Immunologic assays of hematopoietic cells were performed
in two patients. In patient 1, 86% of peripheral blood mononuclear cells
(predominantly blasts) reacted with a monoclonal antibody specific for
granulocytes and monocytes (MMA), and 15% of mononuclear cells reacted with
Tab, a monoclonal antibody specific for megakaryocyte-platelet
glycoproteins (PGP) IIb and IIIa. In patient 2, 41.5% of peripheral blood
mononuclear cells (predominantly blasts) were MMA-positive, 22.5% were
Tab-positive, and 40% reacted with rabbit anti- human PGP. These results
suggest either that two subpopulations of blast cells exist in tET, or that
blast cells simultaneously express surface markers of
myeloblastic/monoblastic and megakaryoblastic differentiation. In these
three and in nine previously reported cases of tET, neither age, sex, nor
previous therapy were obvious etiologic factors. tET occurred 24.2 +/- 14.4
mo after diagnosis of essential thrombocythemia, and a majority of patients
had hepatomegaly and/or splenomegaly, anemia, leukocytosis, and
thrombocytopenia. Leukemic cell morphology was myeloblastic and/or
monoblastic in 12/12 patients, 5/12 had marrow fibrosis. Despite various
treatments, death occurred in 3.6 +/- 2.7 mo; one patient had a brief
complete remission.
Volume 63,
Issue 4,
pp. 866-872,
04/01/1984
Copyright © 1984 by The American Society of Hematology
