多数の癌化を伴った胃のpolypoid adenomatosisの1例

Polypoid Adenomatosis with Multifocal Cancerous Transformation of the Stomach, Report of a Case

　胃角から噴門までの広い中間帯に限局して58コのpolypoid lesionがみられたlocalized polyposis¹⁾の1例を報告する．個々の隆起は無茎または有茎性で，その基本構造は好酸性の強い腺窩上皮類似の上皮からなる腺管増生による隆起であるが，平坦な粘膜内でも腺窩上皮様腺管の増生，延長と粘膜深部での囊胞状拡張やexpansiveな結節状の増殖巣を認めることから腫瘍性性格を持つと考えざるをえない．そこで個々の隆起をadenomaと診断し，本症例はpolypoid adenomatosisと呼ぶのがもっとも適当であると考えた．

　胃の腺腫あるいは腺腫性ポリープに関しては実だ明確な定義はなく，病理学者によってその意義が異なり，さらに同一病理学者でも発表年次によって用語が変っていることはWelch²⁾の指摘の通りで混乱を招いている．本症例はMingのregenerative polyp³⁾，Tomasuloのhyperplastic polyp⁴⁾，佐野⁵⁾，武藤⁶⁾の腺腫性ポリープ，あるいは中村のⅡ型⁷⁾などいわゆる過形成胃ポリープの範疇に属さず，また一方では，Ming，長与⁸⁾のadenomatous polyp，福地，望月⁹⁾のⅡa-subtype，中村Ⅲ型などいわゆる異型上皮の集簇とも明らかに異なるpolyposisで，5コのポリープに癌化が認められたことから癌化のpotentialが高い特殊なタイプの胃のpolypoid adenomatosisと考えられる．胃にこのようなadenomatosisが存在するのは驚きであり，また同時に本症例は大腸と同様に胃においてもadcnoma-cancer transitionを示唆する点で極めて興味深く，調査しえた内外の文献にはこのタイブの胃のpolyposisの報告を見ない．

　A 71-year-old woman was admitted because of an asymptomatic gastric lesion detected by a mass-survey. Gastrofluoroscopy and endoscopy showed numerous polypoid lesions of various shapes and sizes, located mainly in the corpus portion of the stomach. As the biopsy specimens taken from two polyps showed cancerous foci, total gastrectomy was performed. Macroscopically, 58 polypoid lesions, sessile or pedunculated and almost spherical, were characteristically distributed in the intermediate zone. Microscopically, the muscularis mucosae was almost flat in sessile polyps and elevated, forming an inverted V-shaped core, in pedunculated polyps. Marked proliferation, elongation, budding and dense arrangement of the glands lined with eosinophilic foveolar-like epithelia were seen in the superficial layer, connected with the dilated glands at the base. Adenoma-like nodular proliferations of the glands were occasionally seen in the non-polypoid flat mucosa throughout the intermediate zone. This pattern of gland proliferation is indicative of a more active potentiality to proliferate than the ordinary hyperplastic polyps. In our view, an individual polyp is an adenoma, hence a proper term of polypoid adenomatosis of the stomach.

　Interestingly, small foci of tubular adenocarcinoma were found in the surface of five polyps (9％), according to the criteria of malignant transformation of benign polyps. This is a very rare case of gastric adenomatosis with a strong liability of malignant change.