T(15; 17) Associated with Primary Myelofibrosis: a Case Report of an Unusual Clinical Presentation and Diagnostic Dilemma

Background: primary myelofibrosis (PMF) is a myeloproliferative neoplasm which is associated with clonal molecular and cytogenetic abnormalities (CA) and varied clinical manifestations. While various CA have been previously described, t(15; 17) has not been reported in association with this condition. Case presentation: A 69-year-old male presented with constitutional symptoms, cytopenias and bone marrow biopsy revealed immature blasts with fibrosis. Cytogenetic analysis showed a t(15;17) which initially suggested a diagnosis of acute promyelocytic leukemia (APL). However, flourescence in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR) studies were negative for transcripts promyelocytic leukemia (PML) gene and retinoic acid receptor alpha (RARA) or PML-RARA fusion. Along with these results, a second review of bone marrow histology, flowcytometry and the detection of a calreticulin gene (CALR) mutation helped with the correct diagnosis of PMF. Patient was then treated with ruxolitinib, a JAK (Janus kinase) 1 and 2 inhibitor, and eventually proceeded to receive a matched unrelated reduced intensity conditioning (RIC) allogeneic stem cell transplantation (ASCT) and has been doing well at the 6-month follow up. Conclusions: Our case highlights two points, that the t(15;17) is diagnostic of Acute Promyelocytic Leukemia (APL) in most cases, there are exceptions and it can be associated with other malignancies without causing any APL like features, as noted in this case. Also, that t(15; 17) by itself is never sufficient to diagnose APL without confirmation by other methods and relying solely on cytogenetics without timely confirmatory tests can lead to risks of delay in diagnosis and appropriate management.