A case of anal canal squamous cell carcinoma detected with anal stenosis eight years following resection for rectal adenocarcinoma

An 89-year-old woman underwent low anterior resection for rectal adenocarcinoma (Ra, pT3N0M0, pStage II, Cur A) in 2008. In February 2016, she underwent an outpatient examination because of a defecation disturbance. Lower gastrointestinal endoscopy was performed and the stenotic region was biopsied. However, no malignancy was detected and the stenotic site expanded. However, the patient experienced recurrence of the same symptoms, developed severe anal stenosis, and underwent another examination in December 2016. Magnetic resonance imaging indicated a neoplastic lesion around the entire circumference of the anal canal. Transperineal needle biopsy results indicated squamous cell carcinoma. The patient was diagnosed with postoperative rectal cancer and metachronous anal canal squamous cell carcinoma (P, cT4bN2M0, cStage III b). Laparoscopic artificial anus construction was performed with the aim of unblocking the anal canal stenosis. Considering the patient's age and performance status, radiation therapy was administered. Two months after administering radiation therapy, the tumor decreased in size, and anal pain reduced.