Chronic myeloproliferative neoplasms with concomitant CALR mutation and BCR::ABL1 translocation: diagnostic and therapeutic implications of a rare hybrid disease

Myeloproliferative neoplasms (MPNs) are subdivided into Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) and Ph-negative MPNs. translocation is essential for the development and diagnosis of CML; on the other hand, the majority of Ph-negative MPNs are characterized by generally mutually exclusive mutations of Janus kinase 2 ( ), calreticulin ( ), or thrombopoietin receptor/myeloproliferative leukemia ( ). mutations have been described essentially in and wild-type essential thrombocythemia and primary myelofibrosis. Rarely coexisting and mutations have been found in Ph-negative MPNs. translocation and mutations were initially considered mutually exclusive genomic events, but a discrete number of cases with the combination of these genetic alterations have been reported. The presence of translocation with a coexisting mutation is even more uncommon. Herein, starting from a routinely diagnosed case of -mutated primary myelofibrosis subsequently acquiring translocation, we performed a comprehensive review of the literature, discussing the clinicopathologic and molecular features, as well as the outcome and treatment of cases with and co-occurrence.