深達度診断を誤診した大腸腺腫の1例

Adenoma of the Sigmoid Colon Difficult to Differentiate from Invasive Colon Cancer, Report of a Case

要旨　患者は57歳，女性．腹痛・嘔吐を主訴に当院に搬送された．上部消化管内視鏡検査では，胃体部大彎に広範囲のIIcを認め印環細胞癌であった．大腸内視鏡検査では，S状結腸に約25mmの隆起性病変を認め中心に陥凹様所見を有していたが，十分な空気量を注入すると，弧の硬化像などの伸展不良所見は認めなかった．同時に行った生検ではGroup 4と診断された．大腸X線検査は側面像の撮影はできなかったが，空気量の増加により腫瘍は容易に伸展した．しかし，拡大内視鏡で中心部は不整なV 型pitであり，超音波内視鏡では筋層へ浸潤しているように思えた．手術の結果管状絨毛腺腫であった．本症例は組み合わせ診断を誤って判断したため，深達度を深く読影しすぎた誤診例である．

　A 57-year-old woman was admitted for abdominal pain and vomitting. Endoscopic gastrointestinal examination revealed a long wide IIc tumor in the gastric body with signet ring cell carcinoma. Colonoscopic examination revealed an elevated lesion, about 25 mm in diameter, which seemed to have a central slightly depressed area. The fold around the tumor did not indicate rigidity of the arc in the lumen. The biopsy revealed Group 4 tumor. Barium enema was unable to show the frontal view of the tumor but pneumatic expansion of the colon revealed that the tumor was extensive. In the magnifying view with crystal violet staining, the central lesion of this tumor was shown to have an irregular pit pattern of type V. In the examination using 7.5 MHz endoscopic ultrasonography, the central lesion of the tumor was revealed to be invading the submucosa or muscularis propria. Histological diagnosis was tubulovillous adenoma with moderate and partly severe atypia. Immunohistochemically, tumor cells were shown to be partly positive for p53. This case had been mistakenly diagnosed as invasive sigmoid colon cancer because of the information provided by magnifying endoscopy or endoscopic ultrasonography.

　1) Department of Gastroenterology, Saiseikai Futsukaichi Hospital, Fukuoka, Japan

　2) Department of Surgery, Saiseikai Futsukaichi Hospital, Fukuoka, Japan