小笠原　壽恵
   Department   School of Medicine(Tokyo Women's Medical University Adachi Medical Center), School of Medicine
   Position   Assistant Professor
Language Japanese
Title JAK-2 negative acute monocytic leukemia developed in essential thrombocythemia with JAK2 mutation
Conference The 79th Annual Meeting of the Japanese Society of Hematology
Promoters The Japanese Journal of Clinical Hematology
Conference Type Nationwide Conferences
Presentation Type Poster notice
Lecture Type General
Publisher and common publisherDept.Med. Gastroenterology and Hematology, Unveiled.of Miyazaki
Kotaro Shida, Kazuya Shimoda
Date 2017/10/20
Venue
(city and name of the country)		 Japan, Tokyo
Society abstract 臨床血液 58(9),556 2017
Summary Essential thrombocythemia (ET) is an indolent myeloproliferative neoplasm (MPN) with a transformation to acute myeloid leukemia in less than 5 % of patients, which usually occurs as acute megakaryoblastic leukemia. We report a JAK2-positive ET patient who developed acute monocytic leukemia, whose clone revealed no JAK2 mutation.
79-year-old man was diagnosed JAK2-positive ET in 2008 and treated with hydroxycarbamide. He complained general fatigue in 2015. His laboratory test revealed WBC of 50 x109 /L with 41% monocytic cells. Bone marrow examination showed hypercellular marrow with 81% monoblasts and promonocytes. Leukemia cells showed positivity for non-specific esterase activity and CD13 and CD36. Cytogenetic analysis of bone marrow cells revealed additional aberrantions of 8 and TET2 but JAK2V617F mutation. He was diagnosed acute monoblastic and monocytic leukemia. Although we did not have the chance to evaluate TET2 mutation in JAK2-mutated cells at the time of ET diagnosis, we speculate that TET2 mutation occurred in MPN initiating cells and was associated with development of JAK2-mutated MPN.The absence of JAK2 mutation in the leukemia cells in this case suggests an emergence of leukemia from the clone distinct from JAK2-negative MPN cells carrying TET2 mutation. The mechanism of leukemic transformation of ET should be explored by detailed genetic analysis in similar cases.