表層拡大型食道表在癌の病理

Histopathological Characteristics of Superficial Flat and Spreading Type Esophageal Carcinoma

要旨　現行の食道癌取扱い規約の病理肉眼分類で表層拡大型食道表在癌は，“目立った隆起や陥凹がなく，長軸方向に5cm以上の拡がりを示す表在型癌”とされている．上記の定義にかなった単純型の表層拡大型表在癌と，一部に隆起や陥凹を伴う混合型の表層拡大型表在癌に分けて病理組織学的な検索を施行した．深達度別の脈管侵襲の程度やリンパ節転移の頻度は一般の表在癌のそれと差異はなかった．混合型の最深部分は0-Ⅰ型や0-Ⅲ型の部分であるが，病変の中心からややはずれて位置する．導管内進展の頻度が高く，癌の進展様式に関与している可能性が示唆された．混合型の浸潤部である0-Ⅰ型の部分は，深達度の浅い0-Ⅱ型の部分より細胞増殖能が高い．p53染色の陽性率は15/19例（78.9％）で，一般の表在癌の30/57例（52.6％）より高かった．

　According to the Guide Lines for the Clinical and Pathologic Studies on Carcinoma of the Esophagus by the Japanese Society for Esophageal Diseases, the gross feature of superficial flat and spreading type esophageal carcinoma (0-Ⅱs) is defined as superficial carcinoma (0-type) spreading more than 5 cm along the longitudinal axis without marked elevation and/or depression. We subdivided them into two types as follows : (1) Group 1 ; Pure superficial flat and spreading type, namely carcinoma spreading with no prominent elevation but with or without slight depression, (2) Group 2 ; Mixed superficial flat and spreading type, namely carcinoma spreading with type 0-Ⅰ and/or 0-Ⅲ components. Detailed histopathological studies, with special reference to p53 expression and Ki-67 labelling index (LI) were analyzed.

　Type 0-Ⅱs cancer showed no difference in lymphatic and/or vascular permeation rates and degree of lymph node involvement in comparison with those of common superficial cancers. In Group Ⅱ, 0-Ⅰ or 0-Ⅲ lesions, which are lesions with the deepest invasion, were not located at the center of the cancers. However, Ki-67 LI was the highest index in such deeper invasive areas. p53 expression rate in 0-Ⅱs was apparently higher than that of common 0-type. As for ductal involvement of the esophageal gland, the incidence in 0-Ⅱs was also the highest in the 0-types. Ductal involvement might be the characteristics of type 0-Ⅱs: Subclassification of smcancer infiltrating only via ductal or glandular involvement is controversial : one depends upon the site of invasion, while the other is according to the amount of invasive cancer mass, irrespective of the location. Further study should be done.