顆粒集簇を主体とした大腸隆起性病変の4症例―X線像による経過を中心に

Four Cases of Colorectal Tumors Presenting a Flat Sessile Elevated Lesion Composed of Multiple Aggregated Granules; With Particular Emphasis on Retrospective Radiographic Study

要旨　大腸隆起性病変の中には，非常に広範な病変でありながら背が低く，その表面性状が大小の顆粒像から成る症例がまれに認められる．文献上，類似する症例の報告が散見されるが，その実態は十分解明されていない．そこでわれわれは，このような症例の蓄積に努めるうちに，経時的・遡及的に検討しえた4例を経験した．この4例に共通する特徴は，病変の拡がりに比較して背が低く，その表面に大小の顆粒像が認められることであった．組織学的には，4例中最終的に切除された2例とも，病変の大部分は絨毛腺管腺腫像から成っていた．また，2例は一部に小さな癌巣を認めた．経過観察中の2例の生検組織像は腺腫であった．次に，注腸X線写真で経時的・遡及的に検討した結果，その初期形態はわずかな顆粒像であり，経過と共に顆粒の集簇した形態を保持したまま，側方への腫瘍径の著明な増大が認められた．

　Four cases of colorectal tumors which had a quite flat and widely extended sessile elevated lesion have been encountered in our institution recently. The surface of these lesions presented multiple and various sized aggregated granules ranging from 1 mm to 7 mm. These lesions obviously differed from the common villous adenoma of the colon in several aspects such as the shape, the configuration of the tumor surface, the histological findings and the mucous secretion. Retrospective and prospective radiographic analyses on these cases were made. The diagnostic significance and some presumptions concerning the growing process of the lesions were summarized as follows.

　(1) The speed of growth of the lesion was relatively slow as compared with carcinoma. The tendency of the tumor was mainly to grow on the surface of mucosa and less deeply into the visceral wall.

　(2) When the lesion grew in size, the configuration of aggregataed granules on the lesion presented essentially the same pattern.

　(3) Histological examination revealed tubulo-villous adenoma with poor mucous secretion in the major part of tumor. Very small focal adenocarcinoma were discovered in two operated cases. However, in two biopsy cases, no malignancy was able to be proved.