内分泌細胞癌への分化を伴った早期胃癌の1例

Early Gastric Cancer with Focal Differentiation to Endocrine Carcinoma, Report of a Case

要旨●患者は70歳代，男性．食道癌内視鏡治療後の経過観察として行った上部消化管内視鏡検査で胃体上部前壁に周辺隆起を伴う陥凹性病変を認め，生検で高分化管状腺癌と診断された．拡大観察では陥凹辺縁部に明らかな境界を伴う不整な顆粒乳頭状構造を認め，高分化管状腺癌に矛盾しない所見であったが，陥凹部の大部分では無構造を呈し，低分化腺癌の混在が疑われた．EUSでSM2と診断し，外科的手術の適応と判断したが，患者の強い希望により相対的適応として内視鏡的に切除した．病理診断では，陥凹辺縁部は高分化管状腺癌が主体であったが，陥凹部の大部分は低分化腺癌で，病変深部では内分泌細胞癌への分化を伴いながらSMへ浸潤していた．

　The patient was a 71-year-old man with a history of endoscopic treatment for esophageal cancer. Follow-up upper esophagogastroduodenoscopy revealed a depressed lesion with elevation at the periphery in the anterior wall of the gastric body. On biopsy, the lesion was diagnosed as well-differentiated adenocarcinoma. Magnified observation showed irregular granular or papillary structures with a demarcation line in the periphery of the depressed lesion. These findings were consistent with the diagnosis of well-differentiated adenocarcinoma, and the majority of the depressed lesion showed no structures suggesting the presence of poorly-differentiated adenocarcinoma. On endoscopic ultrasound, the lesion was classified as cTiB2 Although open surgery was indicated, endoscopic treatment was performed due to patient preference, and the lesion was endoscopically resected. Histological examination showed that the periphery of the depressed lesion was mainly well-differentiated adenocarcinoma while the central portion of the depressed lesion was mainly poorly-differentiated adenocarcinoma. Furthermore, the deep portion of the lesion had invaded the submucosal layer and contained cells that had differentiated into endocrine-cell carcinoma.