A Case or Collision Tumor of the Anal Canal

Toshihiro Osaki*, Koshi Ando, Kiyoshi lsobe, Junichi Miyata, Shunji Mori

Department oF Surgery, Sizuoka Red Cross Hospital
*Second Department of Surgery, School of Medicine, University of Occupational and Environmental Health

A case of collision tumor consisting of a well-differentiated adenocarcinoma with marked papillary proliferation and mucinous carcinoma with mucous lake of the and canal is reported. A 58-year-old man complained of mucus seeping from his anus. Endoscopic examination revealed a Borrmann type-1 tumor of the anal canal, and a biopsy specimen showed well-differentiated adenocarcinoma. Abdominoperineal excision of the rectum was performed. Macroscopic examination of the surglcal specimen revealed a polypoid tumor bordered by a flat elevated tumor on the orad side of the dentate line. Histological examination showed a collision tumor consistihg of mucinous carcinoma with atypical cells floating in mucus and well-differentiated adenocarcinoma with marked papilla formation. A collision tumor is a unique tumor among multiple cancers, especially in the colon and rectum. This case represents an extremely rare case of co1lision tumor of the anal canal.

Key words
collision tumor of the anal canal, well differentiated adenocarcinoma, mucinous carcinoma

Reprint requests
Toshihiro Osaki Second Department of Surgery, School of Medicine, University of Occupational and Environmental Health
1-1 Iseigaoka, Yahatanishi-ku, Kitakyusyu, 807 JAPAN

Accepted
January 8, 1992

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