上部食道括約筋直下に存在した孤立性異所性胃粘膜の2症例

Heterotopic Gastric Mucosa in the Upper Esophagus, Report of Two Cases

要旨　上部食道に孤立性に存在する異所性胃粘膜は，胎生期の円柱上皮から扁平上皮への置換不全が成因とされる．その頻度は欧米では約4％，本邦では内視鏡的に0.45％が診断されるにすぎず，大部分はいずれも径5mm以下と小さい．今回報告した2症例中，第1例（44歳男性）は心窩部不快感などの症状を有し，内視鏡で上部食道に孤立性赤色調粘膜域を認め，コンゴーレッド法による酸分泌能および生検組織で壁細胞を含む胃粘膜を証明した．第2例（43歳男性）は，内視鏡検査の際，偶然上部食道に赤色調粘膜（径約1cm）を発見し，生検により壁細胞を含まない胃粘膜を証明した．本病変より発生した腺癌の報告もあり，今後2症例の厳重な経過観察が必要である．

　The etiology of ectopic gastric mucosa in the upper esophagus is considered an incomplete replacement of columnar epithelium by squamous cell epithelium in the embryonal period. By endoscopic observation, it was revealed that the incidence of ectopic gastric mucosa in the upper esophagus is about 4% in Europe and America but only 0.45% in Japan.

　We reported two cases of heterotopic gastric mucosa that covered a large area in the upper esophagus. One case was a 44-year-old man who was complaining of epigastric discomfort. Endoscopic examination revealed three patches of ectopic gastric mucosa, each with a size of more than 10 mm, at a distance of 17 to 20 cm from the incisor teeth. By Congo red staining method using tetragastrin, an acidic secretion of gastric mucosa was revealed. Microscopical findings of biopsy specimen showed gastric-like glands which contained parietal cells.

　Another case was that of a 43-year-old man who had no complaints of discomfort. Endoscopic findings showed three patches of ectopic gastric mucosa, each with a size of about 10 mm, in the upper esophagus. Histopathological findings showed the mucosa-like gastric epithelium, which contained no parietal cells. Ectopic gastric mucosa is commonly located just below the upper esophageal sphincter, and it is difficult to detect endoscopically. Careful observation is necessary. Since a few cases of esophageal adenocarcinoma derived from ectopic gastric mucosa have been reported from time to time in Japan and Germany, our cases need to be followed-up carefully.