直腸カルチノイド腫瘍の臨床病理学的検索―転移例と非転移例の比較を中心に

Clinicopathological Study on Carcinoid Tumor of the Rectum―Mainly on Comparison of Cases with Metastasis and Those without Metastasis

要旨　直腸カルチノイドをA群（転移群：12症例12病変）とB群（非転移群：14症例15病変）に分け，臨床病理学的立場から比較検討した．A群に大腫瘍径，中心陥凹・潰瘍形成，深い深達度，脈管侵襲陽性，多い核分裂像，高いKi-67labelingindex（L. I.），p53陽性細胞出現のものが有意に多かった．組織型はA群B群ともに曽我分類のB型と混合型（A＋B型）が約80％を占めており両群間に明確な差はなかった．以上の結果から，本腫瘍の悪性度の指標としては，腫瘍径（1cm以上），深達度，中心陥凹・潰瘍形成，核分裂像（＞2個/10HPF），脈管侵襲，およびKi-67L. I.（＞2％）が有用であることを指摘した．そして，これらの因子の多変量解析の結果，独立かつ有意な因子は腫瘍径のみであることが判明したので本腫瘍の最も重要な悪性度の指標は腫瘍径であると結論した．

　Cases of rectal carcinoid tumor were divided into group A (12 lesions in 12 cases with metastasis) and group B (15 lesions in 14 cases without metastasis), and a comparative study was carried out from the clinicopathological standpoint. There were significantly more cases in group A who manifested large tumor size, central depression and/or ulcer formation, deep infiltration, positive vascular invasion, a moderately elevated mitotic index, a moderately elevated Ki-67 labeling index, and appearance of p53 positive cells. Histologically, approximately 80 percent of cases of both group A and B showed Soga's classification type B and mixed type (type A＋B), and there was no distinct difference between the two groups. From these results it could be pointed out that the findings of tumor size (more than 1.0 cm), depth of invasion (muscularis propria or beyond), central depression and/or ulceration, mitotic index (＞2/10HPF), vascular invasion and Ki-67 labeling index (＞2 ％) are useful predictive criteria in the assessment of the malignant nature of these neoplasms. In addition, as a result of multivariate analysis of the above factors it was found that only tumor size was an independent and significant factor. Thus, it was concluded that the most important malignancy criterion of this neoplasm is tumor size.