2) 大腸腫瘍の異型度診断

Histological Diagnosis of Colon Polyp by Magnifying Endoscopy

要旨　拡大内視鏡による大腸腫瘍の腺管開口部の形態観察¹⁾²⁾は，腫瘍表層部の組織性状を反映していると考えられ，術前診断に極めて重要な手段と考えられる³⁾⁴⁾．腺口形態を拡大観察すると，同じIII型でも腺管形態から様々な組織異型度を呈していることが診断される．すなわちI型と併存するものや辺縁部で過形成を来し，開口部が拡大しているもの，密在するものまで多種多様である．またIII型にV型が一定の領域をもって存在し，異型が高くなっている病変も散見される．このような腺管開口部を見た際に，病理組織学的にどのような組織性状を診断するか，症例呈示を行い概説する．

　The usefulness of magnifying endoscopy (ME) for diagnosis of colon tumor has been already established. The findings from ME correspond with the superficial histologic construction very well. Type III pit pattern, which is divided into IIIL (large) and IIIs (small) pattern by Kudo, represent almost adenomatous lesions. The former is often observed in particular protruded polyps. In contrast, the latter type is characterized in typical depressed lesions. However, type IIIL pit pattern shows various kinds due to the grade of histological diagnosis. Therefore, the polyp, has type IIIL pit co-mixed with type I pit shows the low grade adenomatous galands with normal glands in lesions. But in the high grade adenomatous lesion, type IIIL pit pattern is slightly complicated.

　We present some various cases showing type IIIL pit pattern in the polyp.