側方発育を示したⅡc＋Ⅱa型早期大腸癌の1例

Depressed-Type Early Colon Cancer Showing Laterally Spreading Growth, Report of a Case

要旨　患者は63歳，男性で，大腸癌検診陽性のため大腸内視鏡検査を施行した．直腸S状結腸曲に偽足様所見を呈し，陥凹内に小結節を認めるⅡc＋Ⅱa型腫瘍を認めた．推定深達度はmとしたが，表面陥凹型でX線検査上20mmであったことから高位前方切除術を施行した．実体顕微鏡ではⅢ_L＋Ⅲ_S＋Ⅳ pitを呈し，辺縁隆起ではⅢ_L pitが認められた．病理組織学的には0-Ⅱc＋Ⅱa，tub 1，sm₁，ly₀・v₀，n₀，15×10mmで，陥凹内小結節を含めた3か所でsm浸潤を認め，辺縁隆起部では癌が粘膜表層を這うようにかつ非全層性に拡がっていた．自験例は肉眼形態，辺縁隆起部のpitおよび組織学的所見から非顆粒型側方発育型腫瘍の範疇に入るⅡc＋Ⅱa型早期大腸癌で，陥凹を有する非顆粒型LSTの病態を考えるうえで，また非顆粒型LSTのsm浸潤の初期像として貴重な症例と考えられた．

　A 63-year-old man was admitted to our hospital for the sake of further examination of positive stool Hb. Endoscopic picture showed, in the rectosigmoid colon, a type Ⅱc ＋ Ⅱa tumor with pseudoprodia-like appearance and a nodule in the depressed area. A high anterior rectal resection was performed. Stereo-microscopic picture showed Ⅲ_L＋Ⅲ_S＋Ⅳ pit in the depressed area and Ⅲ_L pit in the marginal elevation, which suggests laterally-spreading growth. The resected specimen showed type Ⅱc ＋ Ⅱa early colon cancer, measuring 15×10 mm in size. Histological examination showed well differentiated adenocarcinoma with scanty invasion of the submucosa. This case was thought to belong to the non-granular type of laterally spreading tumor.