スキルス胃癌と鑑別を要する腫瘍性疾患―転移性胃癌

Metastatic Gastric Cancer

要旨　転移性胃癌はこれまでまとまった報告は少なく，その内視鏡的特徴も多岐にわたっている．その中でもスキルス胃癌と鑑別を要する4型進行胃癌類似型の頻度は非常に低く，乳癌からの転移によくみられる．ともに粘膜下層をびまん性に浸潤する進展形式をとるため，進行した状態では内視鏡・X線造影検査ともに鑑別が困難で，最終的には生検による組織学的診断が必要となることが多い．原発巣が存在する場合には比較的疑いやすいが，特に4型進行胃癌類似型を来す乳癌は，術後数年経過してから出現することも報告されており，注意が必要である．生検の際も粘膜下層の腫瘍組織を確実に生検するようにボーリング生検などの工夫が必要である．

　Few studies have comprehensively evaluated metastatic gastric tumors, characterized by a wide range of endoscopic features. In particular, metastatic gastric tumors simulating type 4 advanced gastric cancer must be differentiated from scirrhous gastric cancer. These tumors are extremely rare, but are often found among metastases from breast cancer. Because such tumors spread by diffusely infiltrating the submucosa, differential diagnosis is challenging on endoscopic as well as radiographic examinations. Final diagnosis usually requires histopathological examination of biopsy specimens. Metastatic gastric tumors are relatively easily suspected in the presence of primary lesions, but breast cancer associated with tumors simulating type 4 advanced gastric cancer has been reported to appear several years after surgery. Caution is therefore required in diagnosis. Aggressive examinations such as boring biopsy should be performed to reliably obtain specimens of submucosal tumor tissue.