盲腸の表層拡大型大腸癌の1例

Superficial Spreading Type of Colonic Cancer in the Cecum, Report of a Case

要旨　患者は70歳，女性．右下腹部痛で受診した．注腸X線検査では盲腸に大きな，表面が顆粒状の平坦な隆起性病変が認められた．大腸内視鏡検査では回盲弁周囲に大きな結節状隆起があり，その盲腸側には表面が顆粒状の平坦な隆起部分が見られた．生検診断は高分化腺癌であった．切除標本では，6.O×5.Ocmの大きさの結節集簇型の病変であった．病理組織診断は高分化腺癌，病変中央の部分の1か所で粘液産生を伴う癌の腺管が粘膜下層に浸潤し，固有筋層まで達していた．また，特に周辺部では絨毛管状腺腫の所見が認められ，この症例の癌の成り立ちにはadenoma-carcinoma sequenceが考えられた．そして，この症例で見られた，腫瘍が側方に広く拡がり，粘膜下層以下へはごく一部で浸潤していたという発育形式はいわゆる表層拡大型腫瘍に当てはまる．

　A 70-year-old woman was admitted to our clinic with right lower abdominal pain. Double-contrast barium enema demonstrated a large, flat polypoid lesion with granular surface in the cecum.

　Colonoscopic findings showed a large, nodular polypoid lesion around the ileo-cecal valve and a flat elevated lesion with granular surface in the bottom of the cecum. Biopsy specimens revealed well differentiated adenocarcinoma and tubulo-villous adenoma.

　The operated specimen showed a flat polypoid lesion with conglomerated nodular surf ace, measuring 6.0×5.0 cm in the cecum. Histologically, this polypoid lesion was diagnosed as well differentiated adenocarcinoma with a small amount of cancer invasion to the proper muscle layer in the center of this lesion. Tubulo-villous adenoma was found in the marginal part of this polypoid lesion. This polypoid cancer was thought to have originated according to the adenoma-carcinoma sequence theory.

　The tumor which showed lateral, wide spreading with minimum deeper invasion in this case belongs to the superficial spreading type of tumor.