予後不良な早期消化管癌の病理組織学的特徴—胃癌

Pathologic Overview of Early Gastric Cancers with Poor Prognosis

要旨●早期胃癌の予後は全体としては非常に良好であるが，頻度が低いながらも遠隔転移を来し予後不良な例が認められる．治癒切除後の再発死亡例に関しては，病理組織学的な再発・転移リスク因子を十分に評価しきれていない可能性，腫瘍に内在するaggressiveな性格・成分や腫瘍細胞の微細な拡散を認識できていない可能性などが課題として考えられる．また，Krukenberg腫瘍や播種性骨髄癌症のような特異な遠隔転移を来す病態が，まれながら早期胃癌でも生じる可能性があること，胎児消化管類似癌と関連腫瘍，内分泌細胞癌，絨毛癌など高悪性度とされる特殊型組織型（成分）が早期胃癌でも認められることには，常に留意する必要がある．

　Generally, early gastric cancer prognosis is excellent. However, although the frequency is very low, some gastric cancers show distant metastases with unfavorable outcome. Regarding fatal recurrent cases after curative resection, the following challenges could be considered：the presently proposed histopathological factors related to recurrence and metastasis would not always be entirely evaluated in every case, or every tumor's aggressive characteristics and elements and its micrometastatic spread would not be recognized sufficiently. Besides, it is crucial to always remember that even early gastric cancers unusually show distinct distant metastases such as Krukenberg tumors or bone marrow disseminated carcinomatosis, and that early gastric cancers could include aggressive special types, such as adenocarcinoma with enteroblastic differentiation, endocrine cell carcinoma, and choriocarcinoma as a whole or as a part.