多発する表面型病変を形成した胃癌原発転移性大腸癌の1例

Metastatic Colorectal Cancers Presenting as Multiple Superficial Type Lesions which Occurred Eight Years after Operation for Gastric Cancer, Report of a Case

要旨　胃癌切除後約8年を経過して大腸に多発性転移を来した68歳女性の症例を経験した．注腸X線および大腸内視鏡検査で全大腸および回腸終末部に径5～20mmでIIa型ないしIIc型の表面型病変が約40個観察された．10個の病変を内視鏡的に摘除したところ，すべての病変が印環細胞癌であり，粘膜下に微少浸潤を認めた1病変を除き粘膜固有層に限局していた．以前の胃癌は胃体部のIIc様印環細胞癌で深達度はmpであり胃全摘術と脾臓摘出術が行われており，1個のリンパ節転移がみられていた．胃癌と大腸病変での粘液形質を免疫染色で検討したところいずれも胃型の形質を示したため，大腸病変は胃癌の転移と考えられた．胸腹部のCTで転移巣やリンパ節腫大は描出されなかったが，骨髄生検で印環細胞癌が証明されたことから，転移経路は血行性であると考えられた．

　We encountered a 68-year-old woman who suffered multiple colorectal metastases eight years after an operation for gastric cancer. Barium enema X-ray and colonoscopy revealed about forty superficial-type lesions sized 5-20 mm throughout the entire large intestine and the terminal ileum. Ten lesions were resected endoscopically. All of the lesions were signet ring cell carcinoma confined to the lamina propria except for one with minimal submucosal invasion. The previously operated gastric cancer was IIc-like advanced cancer in the gastric body invading the proper muscle layer with lymph node metastasis. Its histology was signet ring cell carcinoma. Immunohistochemistry revealed that both the gastric lesion and the colorectal lesion shared the mucous characteristics of the gastric type. Accordingly, we concluded that the multiple colorectal lesions were metastases from the previously excised gastric cancer. CT scan of the chest and abdomen demonstrated no apparent mass lesions. Histological examination of the biopsy specimen of the bone marrow demonstrated the presence of signet ring cell carcinoma. Blood-born metastasis was suspected in this case.