大腸低分化腺癌と鑑別を要した転移性大腸癌

Two Cases of Metastatic Colorectal Cancers in which Discrimination from Primary Poorly Differentiated Carcinoma was Difficult

要旨　胃癌からの大腸転移で多発する表面型病変を形成し，組織学的に低分化腺癌，印環細胞癌が証明された2症例を呈示した．〔症例1〕は83歳，男性で大腸内視鏡で直腸からS状結腸にIIa＋IIc病変が散在性にみられ，生検では粘膜固有層への低分化腺癌の浸潤がみられた．胃に3型進行癌がみられ，組織学的にも同様であることより大腸転移と判断した．〔症例2〕は68歳，女性で，進行胃癌術後7年9か月後に大腸全域に約40個の表面型病変（IIa，IIc）がみられた．一部の病変を内視鏡的に摘除したところ，印環細胞癌が主に粘膜固有層に限局して浸潤していた．胃癌と大腸病変での粘液形質を免疫染色で検討した結果，大腸病変は胃癌の転移と考えられた．

　We encountered two cases in which metastatic colon cancers from gastric cancer showed superficial type lesions. The first case was an 83-year-old man, in whom colonoscopy revealed several IIa＋IIc type lesions from the rectum to the sigmoid colon. Biopsy showed the histology of poorly differentiated adenocarcinoma. An advanced type 3 gastric cancer was found by upper GI endoscopy, and the histology of the biopsy specimens was the same as those of colorectal lesions. The second case was a 68-year-old woman who had undergone an operation for gastric cancer seven years and nine months previously. Barium enema X-ray and colonoscopy revealed about forty superficial type lesions（IIa or IIc）in size throughout the entire large intestine. Some lesions were resected endoscopically and the histology demonstrated signet ring cell carcinomas which were mostly confined to the lamina propria. Histology was compared with previously operated on gastric cancer by Immunohistochemical staining revealing the same mucous characteristics as the gastric type.