大腸隆起性病変の病理

Clinico-pathological Aspects of Benign Polypoid Lesions of the Colon and Rectum

　わが国における下部腸管疾患の頻度は，従来，欧米に比べて著しく低かったが，近年増加の傾向が認められている．それと共に，下部腸管疾患に対する関心も高まりつつあり，胃疾患研究におけると同様な幅広い研究体制の確立が望まれる．

　胃疾患と異なり，腸疾患においては隆起性病変が病理学的にも臨床的にも主役を占めており，癌とも最も関係が深いと考えられている．隆起性病変には理論的に良性，悪性，上皮性，非上皮性があり，それらの組み合せにより4種のカテゴリーがあるわけであるが，今回は日常もっとも遭遇することの多い良性上皮性ポリープの病理とその臨床的取り扱い方を，主として癌と対比しながら概説することにしたい．以下，著者の経験をもとに親しく教えを受けたSt. MARK'S病院Dr. Morsonらの考え方の紹介を主にして筆を進めていくことにする．

　Benign polypoid lesions of the large bowel were divided into four groups on the basis of histological differences, and their histological features and clinical implication were described in detail with special reference to malignant potential.

　Metaplastic polyps are very common small sessile lesions in the rectal and colonic mucosa and there is no evidence that they are in any way related to adenoma or carcinoma. Usually they do not require any special treatment.

　Polyposis in colitis occurs as a result of mucosal inflammation and is better called inflammatory polyposis than pseudopolyposis. There is no evidence that inflammatory polyposis is related to the development of cancer in ulcerative colitis.

　Both juvenile polyp and Peutz-Jeghers polyp are hamartomatous in origin and are not precancerous.

　Adenoma is a benign neoplastic lesion of the intestinal epithelium. Tubular adenoma villous adenoma and papillary adenoma are words which describe the differet growth patterns of adenoma. The cytological changes are much the same and they are fundamentally due to the same disease.

　Polyp can be single or multiple and numerous polyps make polyposis.

　Adenoma has malignant potential which is more closely related to the size of the tumour than the difference of the growth patterns. The idea by Morson that for purpose of clinical diagnosis and treatment, the best criterion for malignancy is invasion through the line of the muscularis mucosae was introduced. If there is no submucosal invasion, the polyp will behave as a benign lesion, provided that it is completely removed. The management of adenoma and so-called malignant-polyp was also described in detail.