PG type隆起型早期大腸癌の定義と判定基準—NPG typeとの相違も含めて—内視鏡の立場から

Definition and Endoscopic Diagnostic Criteria for PG Type Early Cololectal Tumors:Including Differences from NPG Type Tumors

要旨●内視鏡診断による大腸腫瘍のPG/NPG typeの鑑別の可能性について検討した．当施設で経験した拡大内視鏡観察後に切除された病変のうち実体顕微鏡観察にて標本の切り出しなどを行った大腸腺腫・早期癌172病変（大腸鋸歯状病変を含む）のうち，隆起型，表面隆起型，陥凹型の各病変を抽出し，拡大内視鏡所見の特徴と病理組織像におけるPG/NPG typeの対比を行った．その結果，腫瘍性病変と周囲正常粘膜との境界部分においてI型pitの介在を指摘することがPG/NPG typeの鑑別のポイントと考えられたが，症例によっては病理割面であっても厳密に分類できない不確定要素が含まれていることが示唆された．また，translational researchを通じて大腸腫瘍の発育進展には多様性があることが証明されてきた現在において，臨床的にPG/NPG typeを検討することの意義が薄れていると考えられた．

　We examined the possibility to differentiate polypoid growth type（PG）/non-polypoid growth type（NPG）of colorectal tumors by endoscopic diagnosis. The samples were 172 colorectal adenomas and early-stage cancer lesions（including serrated lesion）, which were observed by both magnifying endoscopy in vivo and stereomicroscopy in vitro at Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine. Protruded, flat-elevated, and depressed lesions were extracted from these lesions. The characteristics of magnifying endoscopic findings were compared with histopathology, in particular we focused on whether the developmental progress of the marginal part of the lesion was polypoid growth or non-polypoid growth. As a result, PG/NPG could be differentiated by confirming the intercalation of type I pit at the boundary between the neoplastic lesion and surrounding normal mucosa. However, some cases contain uncertain factors that cannot be determined. Moreover, PG/NPG has been considered to have a lesser significance in clinical research because of diversity in the developmental progress of colorectal tumors, which is proven by translational research.