Ⅱb型早期胃癌のX線診断

Radiological Diagnosis of Type Ⅱb and Ⅱb-like Lesions of the Stomach

　近年，臨床的に診断されて手術された早期胃癌の症例数が急増するに伴い，Ⅱc（またはⅡa）とするのには，あまりにも凹凸の差が軽微であり，X線で現わすのにも非常に骨が折れるといった症例がかなり集ってきた．そこで，私どもは，これらの症例を純粋のⅡbと判定するのには躊躇するが，Ⅱbに準じた表現，例えばⅡb様病変として取扱った方が現実にそうのではないかといった考えから，昭和43年10月の第6回日本内視鏡学会秋季大会（松本）に「ⅡbのX線診断の可能性について」と題して報告した．が，果して，佐野量造先生をはじめとする諸先生から批判を受けた．供覧した症例はⅡbではなくてⅡcであるというのが主要点であったと思う．当然のことである．しかし，その後，早期胃癌研究会などに提出される症例などをみていると，Ⅱbと判定された症例も，私どもの集めた症例と大同小異のようである．

　一方，癌研病理の中村恭一は，エネルギッシュに胃の切除標本を，詳細に，検索して，5mm以下の微小胃癌を多数集めていた．そこで，昭和42年の夏に，X線および内視鏡のフィルムと病理の資料を持ち寄り，微小胃癌がX線および内視鏡フィルムにどのように現われるものかretrospectiveに検討してみた．この成績は，芳しいものではなかったが，昭和43年の7月の胃癌研究会（仙台），および，昭和44年4月の放射線学会総会（米子）で発表した．

　During the six years 1965 through 1970, 337 cases of early gastric cancer had been operated on in the Cancer Institute Hospital. Of these, the number of the most suitable cases for analysis in the radiological diagnosis of Ⅱb was 17 (18 lesions): one typical Ⅱb lesion, another Ⅱb-like lesion and 16 Ⅱb-like lesions concomitantly found in the course of surgical correction for other types of early cancer. In addition, two more lesions were included which slightly invaded the proper muscle layer (pm). (1) According to the conventional classification these 20 lesions were divided into Ⅱb, Ⅱb＋Ⅱa, Ⅱb＋Ⅱc and Ⅱb＋Ⅲ. Only three lesions were free of ulceration, and the rest had either ulcer or ulcer scar ranging from Ul-Ⅱ to Ul-Ⅳ. (2) One typical Ⅱb and one Ⅱb-like lesion were smaller than 20 mm in diameter and were unassociated with ulceration. Fourteen of 20 lesions were larger than 50 mm, and four of them were over 100 mm in diameter. (3) Their macroscopic characteristics were divided into three varieties: (a) lesion with no difference from the surrounding mucosa; (b) lesion with its mucosal surface more smooth than the normal one; (c) lesion with its mucosal surface more nodular than the encircling normal mucosa. Of these, (c) was most correctly demostrated in a double contrast image. However, at times both (a) and (b) were also visualized in the double contrast picture as a faint barium fleck or difference in barium coating.

　In the same period, 69 lesions of microcarcinoma (7 of Ⅱa, 26 of Ⅱb and 36 of Ⅱc) had been discovered by Nakamura after close histological examination, the results of which seem to show that typical Ⅱb in the strict sense of its definition is to be found in those microcarcinomas less than 5 mm in diameter. Retrospective study of radiological findings in these microcarcinomas has also shown that there were several cases radiologically visualized. Of these, three cases are demonstrated in this paper.