Abstract
We report a case of rectal cancer in a rectal diverticulum with the periproctal abscess. The patient was a 58year-old man with anal pain and high fever. He was diagnosed with cancer in the lower rectum and a periproctal abscess and fistula from at the lower margin of the tumor. After controlling the inflammation, we performed an abdominoperineal excision of the rectum for a preoperative diagnosis of rectal cancer with penetration. Examination of the surgical specimen revealed a cancer in diverticulum at 1.5cm distal to the type I tumor. The cancer in diverticulum made the fistula to the abscess cavity. Histopathological examination revealed that the cancer in diverticulum was moderately differentiated adenocarcinoma but the proximal lesion was well to moderately differentiated adenocarcinoma that had invaded to the sub-adventitia (a1). We failed to detect the cancer in diverticulum before surgery. Cancer in the rectal diverticulum is very rare, but it has possibility of penetration in early stage and small lesion. We must be considered the possibility of malignant diseaseon patients with a periproctal abscess.
