胃の腺腫：私はこう考える

Clinicopathological Characteristics of Gastric Adenoma and Its Significance as a Precancerous Lesion

　はじめに

　胃生検組織分類のGroupⅢ，境界領域病変に相当する病変は，必ずしも同一の疾患概念を示すものではない．これらを手術例でみると異型上皮，ATP，Ⅱa-subtype，扁平ポリープ，腺腫（adenoma）など，種々な呼称で表現されてきた．更に最近ではdysplasiaの概念が導入され，境界領域病変をめぐる諸問題は，しばしば議論の対象となっている．本稿では，内視鏡診断，X線診断，更には生検組織診断上，種々な問題を含んでいる境界領域病変のうち，組織学的に腺腫とみなされる病変の定義，病理形態的特徴像，ならびに前癌病変としての意義について，われわれの知見に基づく見解の一端を記述する．

　Two hundred and thirteen adenomas in 177 patients were examined with respect to the clinicopathological aspects and the significance as precancerous lesions. The results and our conclusions are summarized as follows:

　1) Adenomas were most frequently seen in the resected specimen of early gastric cancer.

　2) Most of the cases were the elderly with the highest frequency in the seventh decade. Male to female ratio was 3.2: 1 in overall, but was nearly equal at 1.3: 1 among cases of pure and simple adenoma.

　3) Most of the lesions were located in either M or A regions, whereas those in the C region were rarely seen.

　4) Most of the lesions were an elevated type (78.4 ％) with Ⅱa-like elevations being particularly most frequent (68.1％).

　5) Most (83.6％) of the lesions were small, less than 2 cm in diameter.

　6) Focal cancer in adenoma, which is thought to be the result of malignant change of adenoma, was found in at least 5 lesions (3.5％). Adenoma concomitant with carcinoma within the same lesion was seen in 23.4％ of 230 adenomas.

　From the macroscopic point of view, the main factors of high cancer coincidence rate were the size larger than 2 cm and configuration of Is or depressed type. From the histological point of view, the factors are papillary features, grade Ⅲ atypia and the so-called “gastric-type” adenoma.