背景粘膜にびまん性過形成性結節を伴った多発大腸癌の1例

A Case of Multiple Adenomas and Adenocarcinomas of the Colon with the Background of Diffuse Nodular Hyperplasia

　最近，われわれは横行結腸から直腸までびまん性に過形成性結節を認め，さらに多発性の腺腫性ポリープと大腸早期癌を合併した症例を経験した．家族性大腸腺腫症では腺腫の芽から腺腫へ，そして多数の腺腫を背景とする粘膜から癌が発生するという過程が明らかにされているが，われわれの症例ではびまん性に無数の過形成性結節を背景病変として腺腫や癌が発生したものと考えられ，この背景粘膜が発癌となんらかの関係があるのではないかと推定される．過形成性（化生性）ポリープそのものからの癌化は否定されている今日，本症例の意義は少なくない．さらに，大腸粘膜にびまん性に過形成性結節を示す症例は，本邦のみならず欧米の文献にもほとんど見出すことができず，極めて貴重な症例と考えられるのでここに報告したい．

　A 38 year-old man was admitted to hospital with a chief complaint of diarrhea. Family history revealed that his sister had been operated on because of rectal cancer at the age of 36.

　The patient had barium enema examination in April 1977, which showed a Ⅱa+Ⅱc-like elevated lesion with two pedunculated polyps and coarse granular changes of mucosa in the colon. Pedunculated lesions were diagnosed as adenoma by endoscopic polypectomy, and the elevated lesion was diagnosed as adenocarcinoma by biopsy. Rather limited descending colectomy was performed considering early cancer (sm cancer).

　Barium enema, performed 6 months after operation, disclosed multiple small flat elevated lesions, less than 5 mm in diameter, which appeared in the midportion of transverse colon and became more crowded toward the distal part of the colon, especially from the anastomosis to the rectum. Endoscopically, colonic mucosa showed edema and only scattered foci of elevation.

　Histologically mucosa of the resected colon showed diffuse multiple hyperplastic nodules with infrequent metaplastic polyps less than 5 mm in diameter.

　With the background of these diffuse nodules, there were microadenomas and intramucosal microcarcinoma, 2 mm in size, in addition to the above described sm cancer and adenomas. Also observed was abnormal glandular hyperplasia even in the flat, normal appearing mucosa.

　Therefore, it can be concluded that adenomas and cancers in this case developed from the mucosa with a background of diffuse nodular hyperplasia, and this combination seems to be very rare from the standpoint of diffuse mucosal abnormality of the colon.