Chronic myeloid leukemia with pure erythroid leukemia blast crisis

Chronic myeloid leukemia (CML), a myeloproliferative neoplasm defined by the presence of the BCR-ABL1 oncogene created by the reciprocal translocation t(9;22)(q34.1;q11.2), can often be controlled by medications that inhibit this constitutive tyrosine kinase. However, if these therapies fail, the disease may progress to a form resembling an acute leukemia. While most of these CML 'blast crises' are characterized by blasts with a myeloid (granulocytic) or lymphoid lineage, these blasts may rarely be predominantly erythroid. Cases of CML erythroid blast crises have been reported; however, secondary pure erythroid leukemia arising from a CML blast crisis has only been definitively reported once before. We report the second definitive case of pure erythroid leukemia with the t(9;22)(q34.1;q11.2) presenting as a CML blast crisis and characterize the morphologic, immunophenotypic, flow cytometric, cytogenetic, and molecular findings.

Automated summary

Chronic myeloid leukemia (CML) is characterized by the BCR-ABL1 oncogene and can often be controlled by tyrosine kinase inhibitors. CML may progress to an acute leukemia, with blast crises typically of myeloid or lymphoid lineage but rarely purely erythroid. Pure erythroid leukemia arising from a CML blast crisis is rare, with only two definitive cases reported.