Extramedullary T‐lymphoblastic blast crisis in a young male with chronic myeloid leukemia: A rare presentation diagnosed on cytology and flow cytometric immunophenotyping

Extramedullary blast proliferations (EBPs) are known to occur in around 15% of chronic myeloid leukemia (CML) patients in the blast phase. Immunophenotypically, the EBPs are commonly myeloid as compared to the lymphoid. Amongst the lymphoid EBPs, T-lymphoblastic type is considerably rare. Furthermore, the occurrence of EBPs at the initial clinical presentation is extremely rare and such presentations almost always portend the occurrence of an imminent hematological blast crisis shortly.