胃原発性小細胞癌の1例

Primary Small Cell Carcinoma of the Stomach, Report of a Case

要旨　われわれは，まれな胃原発性小細胞癌の1例を経験したので報告する．患者は71歳の男性，術前肉眼診断は2型で，形態的には悪性リンパ腫が疑われたが，生検ではtub2であった．手術は幽門側胃切除を施行した．組織学的には，腫瘍細胞は粘膜下主体の増殖を示し，多形性に富み，N/C比大の異型細胞が一部腺管状あるいは索状の増殖を示しながら充実性に増殖しており，核分裂像が目立ち，ロゼット様構造も認められ，Grimelius染色陽性，Chromogranin染色陽性であり，電子顕微鏡で神経内分泌顆粒を認めたことにより小細胞癌と診断した．また，一部周堤の粘膜内に高分化型管状腺癌を認めた．小細胞癌の予後は非常に不良であり，術後注意深い経過観察が必要と思われた．

　We have encountered a rare small cell carcinoma of the stomach in a 71-year-old man. The patient complained of general fatigue and appetite loss. Radiogra-phy and endoscopy of his stomach showed a type 2 lesion located at the posterior wall of the antrum. Radiology and endoscopic examination suggested malignant lymphoma of the stomach, but biopsy materials taken endoscopically from the tumor diagnosed the lesion as moderately-differentiated-type tubular adenocarcinoma. Distal gastrectomy was performed.

　Pathological examination showed that the lesion had two components, tubular adenocarcinoma in the mucosal layer and a cluster of atypical cells with large pleomorphic-shaped nuclei which were arranged homogenously in sheets. However, some part of tumor cells formed a pseudo-rosette, gland-like structure and trabecular pattern. Mitotic figures of tumor cells were frequent. The tumor showed positive staining both with Grimelius stain and with Chromogranin stains. Neurosecretary granules were recognized in the cytoplasm of the tumor cells by electron microscopy. Final-ly we concluded that these atypical cells were small cell carcinomas.

　The prognosis of this tumor is very poor, so the post-operative course must be observed carefully.