オガサワラ　トシエ   Ogasawara Toshie   小笠原　壽恵    所属   医学部 医学科（附属足立医療センター）    職種   講師
言語種別	日本語
発表タイトル	JAK2陽性本態性血小板血症の経過中に発症したJAK2陰性急性単球性白血病
会議名	第79回日本血液学会学術集会
主催者	日本血液学会
学会区分	全国規模の学会
発表形式	ポスター掲示
講演区分	一般
発表者・共同発表者	宮崎大学医学部内科学講座消化器血液学分野 幣光太郎、下田和哉
発表年月日	2017/10/20
開催地 （都市, 国名）	日本　東京都
学会抄録	臨床血液 58(9),556 2017
概要	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.