Clinical, Immunophenotypic and Cytogenetic Features of Megakaryocytic Blast Crisis of Chronic Myeloid Leukemia: A Single Institution Study

We present 15 patients with megakaryocytic (Mk) blast crisis (BC) of a Philadelphia (Ph) chromosome positive CML confirmed by immunophenotype analysis between 1989-2000. The primary aim of this study is to define clinical, immunological, cytogenetic and laboratory characteristics of Mk BC in Ph positive CML. We have done retrospective analysis regarding basic clinical findings, immunologic phenotype, cytogenetic studies
and platelet functions. All patients had significant expression of CD61 (14/14) and CD34 (13/13) antigens, and a high frequency of expression of CD13 (9/12), CD33 (10/12) and CD11b (9/11). The BC in 6/15 patients was presented with thrombocytosis, 7/15 had a normal platelet count and two patients had thrombocytopenia. A grade IV myelofibrosis was present in 8/10 patients. Six patients evolved additional karyotypic abnormalities.
Two patients had extramedullary BC. The serum activity of LDH (med. 1095.6) was elevated in all patients. A platelet dysfunction was documented in 4/5 patient tested. There are no clinical and hematological characteristics specific for Mk BC of CML. Normal or elevated platelet count (med. 427.4 x 109/L) in BC of CML with prominent expression of CD34 and CD61 antigens, and significant myelofibrosis (grade IV) are the most consistent clinical findings.