巨大な囊胞を形成した胃GISTの1例

Gastrointestinal Stromal Tumor (GIST) of the Stomach with Large Cystic Formation, Report of a Case

要旨　患者は30歳の男性．他施設の人間ドックでの胃内視鏡検査にて胃体部小彎から前庭部に及ぶ大きな病変を見いだされ，当院に紹介となった．胃X線検査，胃内視鏡検査にて粘膜下腫瘍と壁外性病変の鑑別が問題となったが，超音波内視鏡検査にて第4層に主座を置く無から低エコーの均一な領域が観察される一方，囊胞壁に充実成分が認められた．CT検査，MRI検査を合わせて，囊胞形成を来した胃GISTの診断にて幽門側胃切除術を施行した．切除標本で同病巣は長径7.1cmに及ぶ球形を呈しており，腫瘍の大半は囊胞であるが，壁の充実成分は病理学的に棍棒状，紡錘形の核を有する長紡錘形細胞が束状に配列増殖し，免疫組織学的にc-kit陽性，CD34陽性，α-smooth muscle actin（α-SMA）陽性，S-100陰性であった．胃GISTが囊胞化を来すことはまれであり報告した．

　A 30-year-old man received medical examination and was endoscopically diagnosed as having a large gastric tumor. He was referred to our department.

　X-ray and endoscopic examination showed the tumor was 7cm in diameter, located in the submucosal parts on the lesser curvature and covered with normal mucosa. The endoscopic ultrasound study made with a miniature probe revealed cystic formation in this submucosal tumor.

　The patient was diagnosed as having GIST of the stomach with large cystic formation. Distal gastrectomy was performed. Pathological examination showed both spindle shaped cells and epithelioid cells in the tumor. With immunohistochemistry study, c-kit, CD34, α-smooth muscle actin (α-SMA) were positive and S-100 was negative in the tumor cells. Finally the tumor was defined as GIST of the stomach with large cystic formation.