FGPに合併した胃底線型胃癌の1例

Malignancy Developing in a Fundal Gland Polyp, Report of a Case

要旨　患者は50歳代，男性．胃体部に数mm～10mm大の山田分類II～III型ポリープを多数認めた．背景胃粘膜に萎縮はなく，鏡検法，尿素呼気試験，血清抗H. pylori抗体ともに陰性であった．肉眼型は表面が凹凸不整であり，完全に癌合併の可能性を否定できなかったため，完全摘除生検目的で10mm大のポリープ3病変に対してEMRを施行した．病理組織結果はいずれも胃底腺ポリープ（fundic gland polyp ; FGP）であったが，そのうち1病変の表層部に高分化型管状腺癌を認め，免疫染色では癌の部分でp53とKi-67が陽性所見を示した．筆者らは，これまでにも家族性大腸腺腫症ではないFGPに胃癌を合併した症例を経験しているが，H. pylori陰性でFGPに胃癌を合併した症例を初めて経験したので報告する．

　We report the case of a 50-year-old male with several Yamada type II─III polyps measuring approximately 10mm in diameter in the gastric body. There was no evidence of background atrophy in the gastric mucosa, and microscopy, urea breath test, and anti-Helicobacter pylori antibodies were all negative. Because the possibility of malignancy could not be ruled out because of the irregular surface, the patient underwent endoscopic mucosal resection of 3 large polyps（＞10mm）for the purpose of complete biopsy. Histopathological examination revealed all lesions to be fundal gland polyps, although one lesion exhibited a well-differentiated tubular adenocarcinoma on the surface. Subsequently, Ki-67 and p53 expression were demonstrated on immunostaining. Including the present case, we have experienced two patients with gastric cancer developing in a fundal gland polyp not associated with familial adenomatous polyposis. To the best of our knowledge, the present case was the first case of gastric cancer developing in a fundal gland polyp in an H. pylori-negative patient.