Takahashi Keitaro, Fujiya Mikihiro, Ichihara Shin, Moriichi Kentaro, Okumura Toshikatsu
Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Asahikawa Department of Surgical Pathology, Sapporo Kosei General Hospital, Sapporo, Japan.
Medicine (Baltimore). 2017 Jun;96(23):e7080. doi: 10.1097/MD.0000000000007080.
Gastric adenocarcinoma of fundic gland mucosa type (GA-FGM) is a rare tumor composed of atypical cells with differentiation toward the fundic gland as well as the foveolar epithelium. Including our case, only 9 cases of GA-FGMs were reported from 2010 to 2016.
An 87-year-old man was referred to our institution for endoscopic resection of a gastric lesion. The tumor was classified as type 0-I + IIa according to the Paris classification. Magnifying endoscopy with narrow band imaging (ME-NBI) revealed different structures of crypts and vessels among the components, illustrating the collision of 2 types of gastric cancer.
We performed endoscopic submucosal dissection and successfully removed the tumor en bloc.
The histological findings differed markedly between the 0-I lesion and the 0-IIa lesion. The superficial part of the 0-I lesion consisted of a papillary structure, and the deeper part consisted of a tubular structure that showed inverted downward growth to the submucosal layer with the lamina muscularis mucosae. Immunohistochemically, the superficial part of the 0-I lesion was positive for MUC5AC, which had differentiated to foveolar epithelium. The deeper part was positive for pepsinogen-I and MUC6, which had differentiated to fundic gland. The 0-I lesion was diagnosed as gastric phenotype of adenocarcinoma differentiated to fundic gland mucosa with upward growth in the superficial part and downward growth in the deeper part. The 0-IIa lesion was composed of a tubular structure positive for MUC2, and it was diagnosed as an intestinal phenotype of well differentiated adenocarcinoma. The boundary was clear, and no transitional tissue was observed between the 0-I and 0-IIa lesions, suggesting that the 0-I + IIa lesion was a gastric collision tumor of GA-FGM and well differentiated adenocarcinoma.
We herein report the first case of inverted GA-FGM colliding with well differentiated adenocarcinoma. ME-NBI can be used to diagnose GA-FGM even if the lesion collides with other types of adenocarcinoma.
胃底腺黏膜型腺癌（GA - FGM）是一种罕见肿瘤，由向胃底腺以及小凹上皮分化的非典型细胞组成。包括我们的病例在内，2010年至2016年仅有9例GA - FGM病例被报道。
一名87岁男性因胃病变接受内镜切除被转诊至我院。根据巴黎分类，该肿瘤被分类为0 - I + IIa型。窄带成像放大内镜检查（ME - NBI）显示各成分之间隐窝和血管结构不同，表明两种类型胃癌相互碰撞。
我们进行了内镜下黏膜下剥离术，并成功整块切除肿瘤。
0 - I病变和0 - IIa病变的组织学表现明显不同。0 - I病变的浅表部分由乳头状结构组成，较深部分由管状结构组成，该管状结构呈倒向下方生长至黏膜下层并伴有黏膜肌层。免疫组化显示，0 - I病变的浅表部分MUC5AC呈阳性，已分化为小凹上皮。较深部分胃蛋白酶原 - I和MUC6呈阳性，已分化为胃底腺。0 - I病变被诊断为浅表部分向上生长、较深部分向下生长的向胃底腺黏膜分化的腺癌胃型。0 - IIa病变由MUC2呈阳性的管状结构组成，被诊断为高分化腺癌的肠型。边界清晰，0 - I和0 - IIa病变之间未观察到过渡组织，提示0 - I + IIa病变是GA - FGM与高分化腺癌的胃碰撞肿瘤。
我们在此报告首例倒向性GA - FGM与高分化腺癌碰撞的病例。即使病变与其他类型腺癌相互碰撞，ME - NBI也可用于诊断GA - FGM。
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