Mousinho, FilipaSantos, PaulaAzevedo, AnaPereira, JoséLemos, RaquelMatos, SóniaViana, JoãoLima, Fernando2021-06-042021-06-042018Mol Clin Oncol. 2018 Sep;9(3):347-3492049-9450http://hdl.handle.net/10451/48325Copyright © 2018 Spandidos Publications. All rights reserved.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.engMyeloproliferative neoplasmsEssential thrombocythemiaLymphoproliferative neoplasmsMonoclonal B cell lymphocytosisJAK2V617F mutationdel(13q)journal article10.3892/mco.2018.16822049-9469