胃型形質の低異型度分化型胃癌の悪性度

Biological Behavior of Gastric Low-grade Carcinoma with Gastric Mucin Phenotype

要旨●胃型低異型度分化型胃癌の悪性度を明らかにするため，胃型低異型度癌成分が粘膜下層以深に浸潤する13例（低異型度群），粘膜下層以深で一部に低異型度癌成分を含む8例（部分低異型度群）を臨床病理学的に検討した．低異型度群は腫瘍径が小さく，深達度が粘膜下層にとどまる症例が大部分で，進行癌症例は13例中2例のみであった．しかし，脈管侵襲を4例に認め，細胞増殖能は通常胃癌と同等であった．予後は低異型度群で1例の死亡例が認められ，再発形式は腹膜播種であった．部分低異型度群では腹膜播種2例，肝転移1例の死亡例を認めた．胃型低異型度分化型癌は低異型度のままでは浸潤傾向に乏しく，予後のよいものが大部分であるが，深部浸潤を示した症例は通常の進行癌と同等の予後を示すものと推察される．

　To clarify the biological behavior of gastric low-grade carcinoma with gastric mucin phenotype, 13 cases with low-grade components infiltrated beyond the mucosa（low-grade group）and 8 cases with both low-and high-grade components infiltrated beyond the mucosa（partial low-grade group）were clinicopathologically examined. In the low-grade group, tumor size was small and tumor depth remained in the submucosal layer in most cases, and only 2 of the 13 cases were advanced carcinoma. However, lymphovascular invasion was observed in four cases, and cell proliferation ability was almost the same as that of an ordinary gastric carcinoma. With respect to prognosis, one patient with peritoneal dissemination in the low-grade group died. In the partial low-grade group, two patients with peritoneal dissemination and one with liver metastasis died. Gastric low-grade carcinoma with gastric mucin phenotype has poor infiltration tendency, and the prognosis in most cases is good. Therefore, we concluded that prognosis in cases with deep invasion is equivalent to that in ordinary advanced carcinoma.