ABSTRACT
Patients with a Philadelphia chromosome-negative myeloproliferative neoplasm may develop a lymphoproliferative disorder; however, the clinical and molecular determinants and the chronological onset of the two events remain unknown. We herein report the case of a 64-year-old man with concomitant diagnosis of high-risk essential thrombocythemia with evidence of a thrombotic event and high-count monoclonal B-cell lymphocytosis (high-count MBL). The patient harbored a JAK2V617F mutation and one of the most common genetic alterations found in chronic lymphocytic leukemia (CLL) (del 13q), which may represent a sign of disease progression. He was initiated on cytoreductive therapy with hydroxyurea 500 mg 3 times per week and hypocoagulation treatment, and is currently under regular surveillance of MBL without CLL criteria.
ABSTRACT
Myeloproliferative neoplasms (MPNs) are classically divided into BCR RhoGEF and GTPase activating protein (BCR)-ABL protooncogene 1 nonreceptor tyrosine kinase (ABL) positive chronic myeloid leukemia (CML) and BCRABL negative MPNs, including essential thrombocythemia (ET). One of the major diagnostic criteria for ET is the absence of the philadelphia chromosome, thus when present it is almost indicative of CML. ET and CML are considered to be mutually exclusive; however, there are rare situations in which patients with ET present positive BCRABL without the features of CML. Although from the literature review, the frequency of JAK2V617F mutation and BCRABL translocation coexistence in MPNs is low, it may be higher than expected. The current study reported cases of two patients with an initial diagnosis of ET in the presence of JAK2V617F mutation and BCRABL translocation by fluorescent in situ hybridization. Both patients presented with a heterozygous BCRABL translocation, and absence of p190 and p210 transcripts, seemingly a der(9) in the background of an ET JAK2V617F mutation.
