EMR/ESD標本の病理学的評価とその問題点—病理診断の立場から

Histopathological Evaluation of the Specimens Obtained by Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection, and Its Problems

要旨●早期胃癌に対する内視鏡的治療が急速な広がりをみせている昨今，切除検体の正確な病理組織学的評価は必須の要件となっている．例えば，腫瘍径，主たる組織型，壁深達度，脈管侵襲の有無，未分化型癌混在の有無，未分化型癌混在部の大きさ，癌巣内消化性潰瘍の有無，切除断端の癌の有無は，必須の検索項目となっている．また，これらは根治度評価の際の重要な判断材料となる．胃癌は，その発育・進展の過程で，しばしば腫瘍内に異なる組織型が出現・混在することがある．こうした癌組織の不均一性・多様性（heterogeneity）を踏まえて，丁寧かつ慎重な病理診断を心がけることが重要である．

　Considering the rapid and wide acceptance and use of endoscopic treatments for early gastric cancer, there is a need for more accurate histopathological evaluation of resected specimens. The following parameters must be recorded in the histopathological evaluation：tumor size（longest diameter）, predominant histological type, depth of invasion, presence/absence of vascular infiltration, distribution of undifferentiated-type carcinoma, presence/absence of ulceration within the lesion, and resection margins. Furthermore, these parameters are also used as significant evidence in the evaluation of endoscopic curability. Intratumor heterogeneity is also observed during the tumor growth and progression of gastric cancer. Therefore, a meticulous histopathological examination of the endoscopically resected specimens is required.