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Megakaryoblastic Blast Crisis in known Chronic Myelogenous Leukemia

Author: Adam Hines, MD, 03/10/2021
Category: Myeloid Neoplasms and acute leukemia (WHO 2016) > Myeloproliferative Neoplasms (MPN) > Chronic Myelogenous Leukemia (CML), BCR-ABL1+ > Blast phase
Published Date: 04/15/2021

58 year old female with known diagnosis of Ph+ CML presented with abdominal pain found to have abnormal complete blood count revealing white blood cell count 134.42 K/uL (reference range 3.80-10.50 K/uL) with a differential of 56% blasts, 7% promyelocytes. Absolute eosinophil count 1.34 K/uL (reference range 0.00-0.50 K/uL), absolute monocyte count 2.69 K/uL (reference range 0.00-0.90 K/uL), absolute lymphocyte count 29.57 K/uL (reference range 1.00-3.30 K/uL), absolute neutrophil count 13.44 K/uL (reference range 1.8-7.4 K/uL). Platelet count 222 K/uL ( reference range 150-400 K/uL). Flow cytometry revealed 48% of cells are megakaryoblasts positive for: CD41, CD61, minimal dim CD33, partial dim CD13, minimal CD117. Negative for: HLA-DR, CD38, CD123, CD34, CD15, CD4, CD11b, CD56. Overall morphology 59% blasts (most small with high N/C ratio some with blebbing). This is consistent with megakaryoblastic blast crisis of Chronic Myeloid Leukemia. The images included in this set reveal a bone marrow biopsy and peripheral blood smear revealing numerous large cells with granular basophilic cytoplasm and cytoplasmic pseudopods consistent with megakaryoblasts along with large and abnormal platelets.