Concomitant JAK2 V617F mutation and rare e1a2 BCR-ABL1 transcript isoform in a patient with myeloproliferative neoplasm

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematologic diseases. World Health Organization classification divides MPNs into different categories based on the presence of an underlying genetic abnormality. The JAK2 V617F somatic mutation is observed in polycythemia vera, primary myelofibrosis and essential thrombocythemia (ET), the BCR-ABL1 fusion gene is observed in chronic myeloid leukemia (CML). JAK2 V617F mutation and BCR-ABL1 translocation have been considered mutually exclusive. We report a case of a 76-year-old woman who initially presented with ET which progressed to CML, reverting to the ET phenotype once the treatment with tyrosine kinase inhibitors was initiated. JAK2 V617F somatic mutation was the first molecular abnormality found, followed by the appearance of the BCR-ABL1 rearrangement, with the uncommon e1a2 BCR-ABL1 transcript isoform, described very rarely in CML. We believe that this might be a “dual” disease, very rarely recognized and described.