粘膜下注入による大腸sm癌の深達度診断―特に“形状保持隆起”と“癌一筋層距離”について

Endoscopic Findings after Submucosal Injection and Depth of Colorectal Cancer

要旨　粘膜下注入で挙上を示したsm癌をVTR再生を元に選出し，それらの形態変化と癌・fibrosisの範囲，程度について組織学的に検討した．5例中3例（Ⅱc，Ⅱc＋Ⅱa，Ⅱa＋Ⅱc）が注入前の病変形態を保ちながら隆起した（形状保持隆起）．これら3例では，病変全体にdesmoplastic reactionが生じており，病変の伸展性欠如を反映していた．1例（Ⅱa）は伸展性が悪い部位のみにdesmoplastic reactionが生じており，伸展した部位は粘膜内病変でfibrosisはみられなかった．病変全体が伸展した1例（Is）はfibrosisに乏しく粘膜筋板が保たれていた．更に癌と筋層との距離を表す癌一筋層距離，癌一断端距離を測定したところ，これらは隆起の悪い病変，部分でその距離が短かった．以上から，sm癌でnon-lifting signのみられない場合でも，その浸潤程度を粘膜下注入所見から推察することが可能であると示唆された．

　It has been found that colorectal cancers with proliferated fibers in the submucosa do not become elevated after a submucosal injection of methylene blue, whereas the normal mucosa surrounding the lesion “lifts”. In a previous study, we have named this phenomenon the non-lifting sign (NLS), and it has proven useful for determining the depth of colorectal cancer. However, a NLS is not seen in submucosal cancers showing minute invasion. This study was undertaken to identify the relationship between the extent of fibrosis and the degree of stretching by submucosal injection. Five invasive colorectal cancers without NLS were investigated. In three lesions with proliferated fiber, lesions were not stretched by submucosal injection. However, these lesions were lifted a) are mucosal lesions b) if they were mucosal lesions c) in the same way as mucosal lesions are lifted. In two lesions with little fiber, lesions were extended and elevated by submucosal injection. In these lesions we measured “the distance between the carcinoma and the muscularis propria (DBCMP)” and “the distance between the carcinoma and the resected line (DBCRL)”. DBCMP was 0.93 ～ 1.38 mm. In well stretching lesions, DBCRL was 0.54 ～ 1.97 mm. In poorly stretched lesions, DBCRL was 0.33 ～ 0.62 mm. It appears that submucosal injection is useful for determining the depth of submucosal invasion.