| 特集名 | 大腸IIcの病理組織診断 --組織診断の違いはどこにあるのか? | |
|---|---|---|
| 題名 | 大腸IIcの病理組織診断 --消化器病理専門医の悪性所見の捉え方 (1) 大腸癌の組織診断基準 --とくにIIc型癌について | |
| 発刊年月 | 1998年 03月 | |
| 著者 | 中村 恭一 | 東京医科歯科大学医学部病理学講座 |
| 【 要旨 】 | 要旨はありません。 | |
| Theme | Histopathological Diagnosis IIc Type of Colorectal Cancer | |
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| Title | Histological criteria for diagnosing colorectal carcinoma | |
| Author | Kyoichi Nakamura | Department of Pathology, School of Medicine, Tokyo Medical and Dental University |
| [ Summary ] | Atypia is defined as a morphological irregularity in comparison with the normal tissue at cellular and structural levels. Histological findings of atypia are divided into two categories, atypia at the structural level and at the cellular level. Atypia are generally grouped into three grades, slight, moderate and severe. Although histological interpretations of malignancy should be done with a summation of atypical grades at both the levels, atypicality at the cellular level is often taken into account more than that of the structural level. In spite of that villous tumors of the colorectum often measure more than 5cm in largest diameter, most of them are histologically diagnosed as benign villous adenoma, because they show slight to moderate atypia at the cellular level. However, villous figures are not observed in the normal mucosa of the colorectum. Therefore, it may be that the villous figure indicates severe atypia at the structural level. There are tubular tumors histologically consisting of many goblet cells. Their major part is also diagnosed as a benign a tubular adenenoma (goblet cell adenoma) on account of slight to moderate atypia at the cellular level. In those adenomas, cribriform figures and tiny gland in gland structures are histologically observed. In addition, histologically finding a "gland in gland" means a glandular budding in the glandular epithelium, and the cribriform figure is a conglomeration of many "gland in gland". The "gland in gland" is sometimes observed in villous tumors. Both the "gland in gland" and cribriform figures are interpreted as severe atypia at the glandular structure level. Giving support to this interpretation, cribriform figures are sometimes observed in mucosal spreading portion of advanced carcinoma histologically classified into mucoid type. Therefore it may be considered with a high probability that a goblet cell adenoma histologically having many cribriform or/and "gland in gland" structure is malignant. As to histological diagnosis of tubular adenocarcinoma discriminating from tubular adenoma, a linear function with two variables, F=0.08x+0.04y-6.59, is very useful, provided that x is N/C and y is the glandular density in unit area, and F > 0 : carcinoma, F< O : adenoma. This function discriminates carcinoma from adenoma with a high degree of accuracy. Meanwhile, there are small depressed lesions (Type IIc) histologically consisting of adenomatous epithelium with moderate atypia. Those depressed lesions should be interpreted as adenocarcinoma of Type IIc, even if their atypicality is moderate, since the great majority of colorectal adenomas and carcinomas macroscopically shows polypoid and ulcerative patterns, respectively. There is a tendency for the atypical grade of mucosal spreading carcinoma is to be lower than that of infiltrating portion of advanced carcinorna. Therefore, on the occasion of making histological diagnosis of lesions limited to the mucosa, it is very important to take this tendency into consideration. |
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