転移陽性未分化型胃粘膜内癌の臨床病理学的特徴

Clinical and Pathological Features of Gastric Intramucosal Undifferentiated Carcinoma with Metastasis

要旨　自験の外科切除未分化型胃粘膜内癌257例を用い，リンパ節転移陽性例の臨床病理学的，および免疫組織化学的特徴につき検討した．対象症例のリンパ節転移率は3.9％（10/257例）で，比較的若年者（p＜0.05），腫瘍最大径が31mm以上の大きい病変（p＜0.05），粘膜筋板（MM）への浸潤を認める病変（p＜0.05）に高く，このうちリンパ節転移に寄与する有意な因子は大きさ（31mm以上：オッズ比10.7，95％信頼区間1.3～87.1）と深達度（MM浸潤：オッズ比4.4，95％信頼区間1.1～17.4）であった．また転移陽性癌はすべて印環細胞癌，もしくは印環細胞を伴う病変であったことも注目すべき事項であった．転移陽性癌に対する免疫組織学的検討では，全例胃型でp53蛋白発現はみられず，明らかな癌層内の2層構造やKi-67陽性増殖細胞の局在性はみられなかった．以上の結果および大きさ，潰瘍（UL）の有無とリンパ節転移の検討から，慎重な検討と患者への十分なインフォームドコンセントを行ったうえでESDが治療として考慮できる病変は，ULの有無に関係なく15mm以下の病変と結論する．

　Among 257 cases of gastric intramucosal undifferentiated carcinoma treated by surgery in our facility, the clinical, pathological, and immunohistochemical features of cases with lymph node metastasis were investigated. A total of 3.9％（10/257 cases）had lymph node metastasis, the incidence of which was higher in younger patients（p＜0.05）and in those with larger lesions≧31mm in maximum diameter（p＜0.05）or with invasion intothe muscularis mucosae（p＜0.05）. Factors contributing significantly to lymph node metastasis were size（≧31mm, odds ratio : 10.7, 95％ confidence interval : 1.3～87.1）and depth of invasion（muscularis mucosae invasion, odds ratio : 4.4, 95％ confidence interval : 1.1～17.4）. All carcinomas with metastases were signetring cell carcinomas or carcinomas accompanied by signet ring cell lesions. Immunohistochemical study of gastric carcinoma with metastasis did not show p53 protein expression, two-layer structures, or localization of Ki-67-positive proliferating cells within the carcinoma layer in any of the present cases. Therefore, based on our observations regarding size, presence of ulcer（UL）, and lymph node metastasis, we concluded that indication of ESD should be lesion≦15mm in size, irrespective of presence of UL, which would allow prudent assessment and sufficient informed consent for the patient.