術前診断しえた早期回腸癌の1例

Early Carcinoma of the Ileum Diagnosed Preoperatively, Report of a Case

要旨　患者は72歳，男性．主訴は食欲不振．近医で施行されたルーチンの注腸検査で，回盲弁から5cmの回腸に腫瘍が指摘された．注腸X線検査で側面撰状変形，内視鏡検査で軽度の緊満感が認められ，直視下生検の所見と合わせ回腸sm癌と診断した．手術切除標本では25×15×高さ11mmの亜有茎性病変で，H・E染色所見から高分化腺癌，深達度SMIと診断された．脈管侵襲，リンパ節転移は認められなかった．免疫組織染色ではras・p21は陰性で，p53は一部の腺管で軽度の染色がみられたにすぎず，腫瘍全体が異型度の低い高分化腺癌であると考えられた．本例は術前組織診断および深達度診断しえた早期回腸癌（SMI）であり，今後このような症例に対する内視鏡的粘膜切除術の適応を考えるうえで極めて貴重な1例と考えられる．

　A rare case of early lieal cancer diagnosed preoperatively is reported. A 72-year-old male presented at a local hospital with the complaint of anorexia. By a barium enema examination, an irregularly shaped polypoid tumor was detected in the ileum 5 cm proximal to the ileocecal valve. The contour of the lesion seen at this examination suggested submucosal invasion. Examination of a colonoscopic biopsy specimen from the tumor led to a diagnosis of well-differentiated adenocarcinoma. Surgical resection was performed. Detailed histologic examination of the resected tumor, which measured 2.5×1.5×1.1 cm, confirmed the suspicion of its being a well-differentiated adenocarcinoma, which was located mainly in the mucosa, partially penetrating the muscularis mucosae in only a small area. No invasion of veins or lymphatics was observed. By immunohistochemical examination, the resected specimen revealed slight expression of p53, but no expression of ras-p21. Evaluation for Ki-67 showed a high degree of proliferative activity in the tumor, especially superficially.

　This early lieal cancer was treated by resection because submucosal invasion was suspected. Since, only minimal invasion was seen in the resected specimen, this tumor might have been effectively treated by endoscopic surgery. Small lieal cancers are very rare. Morphologic information from barium enema or endoscopic examinations such as the data in this report are important in establishing the indications for endoscopic resection of such a tumor.