| 特集名 | Villous Tumor | |
|---|---|---|
| 題名 | 病理の立場から (1) 大腸villous tumorの病理組織学的特徴と組織診断 | |
| 発刊年月 | 2001年 01月 | |
| 著者 | 伴 慎一 | 埼玉医科大学第二病理学教室 |
| 著者 | 大倉 康男 | 埼玉県立がんセンター臨床病理部 |
| 著者 | 中村 恭一 | 横浜赤十字病院病理部 |
| 【 要旨 】 | 要旨はありません。 | |
| Theme | Villous Tumor | |
|---|---|---|
| Title | Histopathologic features and diagnosis of colorectal villous tumors | |
| Author | Shin-ichi Ban | Department of Pathology, Saitama Medical School |
| Author | Yasuo Ohkura | Department of Pathology, Saitama Cancer Center |
| Author | Kyoichi Nakamura | Department of Pathology, Yokohama Red Cross Hospital |
| [ Summary ] | Colorectal villous tumors are a form of epithelial neoplasia of the colorectum, defined by their macroscopic and/or histologic villous structure. They usually display dominant intramucosal growth and are often diagnosed histopathologically as adenomas. However, extremely well-differ entiated tumors, showing submucoal invasion, are not rare among villous tumors, and definite carcinoma foci frequently coexist in villous tumors, both of which make histopathologic diagnosis not straightforward. Even in typical villous tumors, various quantities of tubular structures are almost always inter mingled with the villous structure, and there is a gradual transition between the villous structure and the tubular structure. We have tentatively defined the villous tumor as an epithelial neoplasia, more than 50% of which histologically display a villous architecture. The key point is how we evaluate the villous structure in regard to the histopathologic diagnosis of benign and malignant epithelial neoplasia of the colorectum. To ascertain that point, we reviewed the histopathologic features of colorectal villous tumors, in conjunction with morphometric analysis using the Index of Nucleus-Gland ratio (ING). Based on the results obtained, we concluded the following : (1) Colorectal villous tumors with cytological atypia graded as borderline or benign frequently show submucosal invasion, and so villous tumors should generally be regarded as potentially malignant. (2) The villous structure should be regarded as one type of structural atypia, having a potential for malignacy, in regard to the histopathologic diagnosis of colorectal epithelial neoplasia. (3) The submucosal invasion of villous tumors often lacks a desmoplastic reaction, and should not be regarded as signifying pseudoinvasion. We performed an immunohistochemical study to ascertain the kineic cellular activity (MIB1,PCNA) and phenotypic (cytokeratin 20: CK2O, human gastric mucin: 45M1) profiles of colorectal villous tumors. Villous tumors primarily represented a mature, differentiated phenotype (CK2O positive) and a gastric phenotype (45M1 positive). Some villous tumors showed an organoid growth pattern, that is, a distribution of CK2O positive cells and of MIB1/PCNA positive cells, which were somewhat similar to those of the normal crypt pattern. These features are shared with so called serrated adenomas. Some villous tumors presented a prominent serrated appearance that compelled us to place them in the category of serrated adenomas. However, considering the fact that focal, serrated foci were frequently observed in villous tumors, and the cell kinetic and phenotypic features described above were observed, not only in villous tumors with a prominent serrated appearance but also in those without a prominent serrated appearance, it is problematic to place the former tumors into the category of serrated adenomas. |
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