MPN-196 Unusual Association Case of Janus Kinase 2 Mutation and BCR-ABL Transcripts: Successful Treatment With Hydroxyurea

Abstract

It is well known that mutations (like JAK2) are mutually exclusive events in myeloproliferative neoplasms (MPN). The presence of mutations (like JAK2) is seen in BCR-ABL1-negative MPN, but its presence with chronic myeloid leukemia (CML) is a rare finding; only a few cases have been reported (1). In this case, we describe patients who had both mutations (BCR-ABL and JAK2 V617F). We present the case of a 37-year-old man referred to our clinical department in 2017 for thrombocytosis. He had a history of arterial hypertension, was a chronic smoker and occasional alcoholic, and had a right fifth toe amputation in 2013. We discovered an asthenic patient with no splenomegaly and amputation of the third toe on the right foot on clinical examination. A complete blood count revealed that the patient was thrombocythemic (platelet [PL] counts of 1,783,000/mm3), had neutrophil leukocytosis (21,300/L), and had a hemoglobin level of 12 g/L. JAK2 V617 mutation was positive, and transcript BCR-ABL (M-bcr) was found by RT-PCR quantification to be 0.082%. However, karyotype analysis revealed that he was 46 years old, XY. His bone marrow was hypercellular with an increased number of megakaryocytes. The patient was followed in the cardiovascular department for his microangiopathy, which resulted in a second amputation of the right third toe in 2017. When he did not achieve complete hematological remission after one month on imatinib mesylate 400 mg daily, the dose was increased to 600 mg/J. Due to treatment failure with PL counts around 100,000 after 6 months, the treatment was changed to hydroxyurea (1 g/J) and imatinib was discontinued. The patient had been in complete hematologic remission for the previous 3 years. Several cases of concomitant JAK2 myeloproliferative disorders and BCR-ABL transcript have been reported. This hybrid disease is more likely to be misdiagnosed because it is underdiagnosed. Patients with association had a poor response to imatinib (3), which was also the case in our patient, who had a good hematological response to hydroxyurea but a poor response to imatinib.