Acute megakaryocytic leukemia in essential thrombocythemia: an unusual evolution?

Abstract

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder that can rarely undergo leukemic transformation either in treated (3-7%) or untreated patients (1%). Evolution to myeloblastic or myelomonoblastic acute leukemia is commonly described in the literature, whereas lymphatic and megakaryocytic forms are considered unusual. Here, we report three cases of acute megakaryocytic leukemia (LMA-M7) among 11 acute leukemic transformations observed in our series of 321 ET patients. LMA-M7 was diagnosed employing immunophenotyping according to FAB criteria. These recurrences of LMA M7 suggest that this kind of evolution cannot be considered rare or casual in ET.

Essential thrombocytemia progressing to Ph+ chronic myeloid leukemia with megakaryoblastic blasts, following anagrelide withdrawal

“…She is currently receiving imatinib at a dose of 200 mg OD orally, and her creatinine levels have returned to normal. Previous studies showing ET progression towards leukemia with t (9;22) and megakaryoblastic M7 appearances have already been reported in the literature [2][3][4]. This case further highlights a possible link between ANA and leukemia.…”

Essential thrombocythemia terminating in pure erythroleukemia

“…Thus, in ET, in which the megakaryocytes and platelet production dominate the chronic phase, most secondary leukemias were of myeloid differentiation [7,8,10,11]. In only a few patients, ET evolved into megakaryoblastic leukemia [8,11,12]. We present the exceptional case of transformation of ET into pure erythroleukemia.…”

“…This reflects the presentation of ET since thrombocytosis is the principal clinical feature, while proliferation of the neoplastic megakaryocytes is the morphological hallmark [1,16]. In contrast, most secondary acute leukemias in ET are of myeloid differentiation [7,10,11], and only few cases of megakaryoblastic differentiation are described, mostly admixed with myeloblastic differentiation [11,12], thus indicating an ''aberrant'' differentiation of the neoplastic cell clone in the blastic phase.…”

“…The neoplastic clones in CMPDs are able to differentiate into the cell lines that predominate the chronic phase but also into other lineages in the blastic phases of disease. Thus, in ET, in which the megakaryocytes and platelet production dominate the chronic phase, most secondary leukemias were of myeloid differentiation [7,8,10,11]. In only a few patients, ET evolved into megakaryoblastic leukemia [8,11,12].…”

Acute biphenotypic leukemia arising in a patient with essential thrombocythemia

“…It is believed that there are risk factors that predict transformation to acute leukemia, which include cytogenetic abnormalities, myelofibrotic features in the bone marrow, and the use of cytotoxic agents [9]. Evolution to AML is commonly described in the literature, while transformation to acute lymphocytic leukemia (ALL) is considered unusual [10]. Transformation to acute biphenotypic leukemia is a very rare event in the evolution of ET.…”