炎症性ポリープ―病理診断の立場から

Clinicopathological Features of Inflammatory Polyp

要旨　非腫瘍性大腸ポリープは，過形成性，過誤腫性，炎症性などに分類される．炎症性大腸ポリープは，炎症性腸疾患を背景粘膜に有する狭義の炎症性ポリープと，背景に炎症性腸疾患がないが病変自体に炎症性変化がみられる広義の意味での炎症性ポリープが存在する．本稿では，両者を炎症性ポリープとして取り扱った．日常診断上問題となる広義の炎症性ポリープの頻度は，内視鏡的に摘除されたポリープの内4.2％と，頻度的には少ない病変であった．狭義の炎症性ポリープと広義の炎症性ポリープの各種典型病変を，その組織像を中心に解説した．また，粘膜および腸管壁自体には炎症性変化がないものの，周囲臓器の炎症性変化に伴いポリープ病変が出現する疾患もみられ，その病変についても解説した．炎症性ポリープの病理診断の際には，組織学的特徴を熟知していることはもちろんであるが，病変の分布や大きさ，経時的な推移，憩室や他疾患の有無などの臨床情報も極めて重要である．

　Non-neoplastic colon polyps are classified into categories including hyperplastic, hamartomatous, and inflammatory. Inflammatory colon polyps can be further subdivided into inflammatory polyps in the narrow sense, which possess inflamed mucosa and develop in inflammatory bowel disease, and those in a wider sense, in which the lesion itself displays inflammatory changes and there is no background of inflammatory bowel disease. In this paper, both types are treated as inflammatory polyps. The frequency of inflammatory polyps in the wider sense, which is an issue in everyday diagnosis, is low, accounting for only around 4.2％of endoscopically resected polyps. We discuss the typical lesions of inflammatory polyps in both the narrow and wider senses, focusing on histopathology. In some disorders, polypoid lesions may appear that are associated with inflammatory changes in the surrounding organs despite a lack of any such changes in the mucosa or intestinal wall itself, and we also discuss these lesions. In the pathological diagnosis of inflammatory polyps, it is important to have full knowledge of not only the histopathological characteristics, but also clinical information such as the distribution and size of lesions, how they change over time, and the presence of diverticula or other disorders.