胃の非腫瘍性ポリープの病理所見

Pathology of Nonneoplastic Gastric Polyps

要旨●胃に散発性・孤発性に生じる非腫瘍性ポリープ病変（近年，遺伝子変異を伴うことから腫瘍性病変に位置付けられつつある良性病変も含む）は，上皮性変化を主体とした粘膜組織由来の病変と，粘膜下を主座とする腫瘤性病変に起因するものとに分けられる．前者には胃ポリープ病変として最も頻度の高い胃底腺ポリープと過形成性ポリープが含まれる．まれな病変ではあるが，Peutz-Jeghers（型）ポリープは，過形成性ポリープとの鑑別を要する可能性がある．後者はhamartomatous inverted polyp，異所性膵，炎症性線維性ポリープが主な病変であるが，粘膜下病変と被覆粘膜組織との関係はそれぞれ異なる．これらの病変を正しく診断するためには，背景粘膜を含めた病変の病理組織学的成り立ちが病変全体の形態にどのように反映するのかを理解しておくことが重要と考えられる．

　Sporadic/solitary nonneoplastic polypoid lesions arising in the stomach, including some benign lesions that were formerly considered nonneoplastic but have recently been referred to as neoplastic based on any genetic alterations, comprise the following two categories：lesions of the mucosa origin predominantly caused by epithelial change and lesions caused by a submucosal tumorous mass elevating the mucosa. The former includes fundic gland polyp and hyperplastic polyp, polypoid lesions that are most frequently found in the stomach. Rare Peutz-Jeghers type polyps could be lesions that need to be differentiated from hyperplastic polyps. Major lesions included in the latter type are hamartomatous inverted polyp, heterotopic pancreas, and inflammatory fibroid polyp ; in each of these, the relationship between the submucosal mass and the overlying mucosa is different. The recognition of the histopathologic architecture of each lesion including the findings of the background mucosa is an essential basis for the differential diagnosis of these lesions.