Rectal cancer with extensive distal intramural spread treated by abdominoperineal resection.

Distal intramural spread refers to microscopic tumor implantation in the intestinal wall, distal to the inferior edge of a macroscopic tumor but rarely beyond 2 cm. We report a case of rectal cancer with preoperatively diagnosed distant intramural spread to approximately 6.5 cm. A 75-year-old woman diagnosed with upper rectal cancer was scheduled to undergo low anterior resection 5 weeks after initial presentation. However, preoperative digital rectal examination and anoscopy under general anesthesia revealed a rectal tumor 4 cm proximal to the anal verge; adenocarcinoma was diagnosed based on frozen section analysis of the rectal tumor. Therefore, abdominoperineal resection was performed, and histopathological examination confirmed a moderately differentiated adenocarcinoma with distal intramural spread of 6.5 cm. The patient died 18 months postoperatively owing to lung metastasis. Although distal intramural spread is rare and can be difficult to detect prior to surgery, repeated rectal examination, with prompt histological examination of suspicious lesions, can ensure earlier diagnosis to achieve better local control by radical surgery including sufficient distal margin.