multiple lymphomatous polyposisを伴うindolent消化管マントル細胞リンパ腫の1例

Indolent Gastrointestinal Mantle Cell Lymphoma with Multiple Lymphomatous Polyposis, Report of a Case

要旨●患者は60歳代，女性．便潜血による近医での大腸内視鏡検査で回腸終末部にリンパ濾胞様顆粒の集簇を認め，精査加療目的に当科へ紹介され受診となった．大腸内視鏡検査では，回腸終末部および回盲弁，S状結腸・直腸に表面平滑で光沢のある大小不同の多発するポリポーシス（MLP）を認め，生検を施行した．病理組織学的には，粘膜内にくびれた核を有する小〜中型の異型リンパ球がびまん性に増殖していた．CD20，CD5，Cyclin D1，Bcl-2が陽性，CD3，CD10が陰性であり，マントル細胞リンパ腫（MCL）と診断した．PET-CTでは回盲部の壁肥厚と，回結腸動脈周囲リンパ節，両側頸部リンパ節，左腋窩リンパ節の腫大とFDG（fluorodeoxyglucose）の弱い集積を認めた．骨髄浸潤は認めず，Ki-67陽性率も低値であることから，indolent MCLを疑い現在経過観察しているが，無症状で著変なく経過している．

　A female patient in her 60s underwent a colonoscopy at a local clinic for fecal occult blood, which revealed clusters of lymphoid follicle-like granules in the terminal ileum. She was referred to our hospital for a detailed examination. A comprehensive endoscopic investigation revealed multiple lymphomatous polyposis with a smooth surface in the terminal ileum, the ileocecal valve, the sigmoid colon, and the rectum. A biopsy was performed. Histopathological assessment of the mucosa revealed densely packed small- to medium-sized atypical lymphocytes with constricted nuclei. Immunohistologically, CD20, CD5, Cyclin D1, and Bcl-2 were positive, whereas CD3 and CD10 were negative. She was diagnosed with MCL（mantle cell lymphoma）. Positron emission tomography-computed tomography revealed terminal ileal wall thickening with weak FDG（18F-fluorodeoxyglucose）accumulation and bilateral cervical, left axillary, and bilateral inguinal lymph node enlargement, all with FDG accumulation. Bone marrow infiltration was not observed, and the Ki-67 positivity was low. Therefore, these lesions were suspected to be indolent MCL. The patient is currently being followed up and has been doing well.