绝大多数结直肠癌起源于腺瘤的概念已被广泛接受。最近日本学者报告非息肉样或凹陷的肿瘤病变,其中一些无腺瘤样成分,认为是肿瘤原发(ｄｅｎｏｖｏ)的证据。由于小的中心凹陷的扁平腺瘤是非息肉样或浸润癌的预兆之一,因此本文再次评价扁平腺瘤的临床病理特征,特别是中心凹陷的? The concept that the vast majority of colorectal cancers originate from adenomas has been widely accepted. Recently, Japanese scholars have reported non-polypoid or depressed tumor lesions, some of which have no adenomatous components and are considered to be evidence of tumor denovo. Since the small centrally depressed flat adenoma is one of the precursors to non-polypoid or invasive cancer, this article again evaluated the clinicopathological features of the flat adenoma, especially in the central depression?