Abstract
Right neck swelling and pain occurred in a 49-year-old man. A Blood count showed a slight increase in platelet count without leukemoid reaction. After a biopsy of the cervical mass and bone marrow aspiration, a diagnosis of extramedullary blast crisis (EBC) of chronic myeloid leukemia (CML) was made. Fluorescence in situ hybridization (FISH) analysis showed a BCR-ABL1 fusion signal, but results of real-time polymerase chain reaction (RT-PCR) for major and minor BCR-ABL1 transcripts were negative. We identified a rare e1a3 BCR-ABL1 fusion transcript. Administration of dasatinib resulted in disappearance of the extramedullary tumor. This is the first reported case of CML-EBC with e1a3 transcript. An aleukemic extramedullary tumor can be the initial presentation of CML.