Synchronous occurrence of adenocarcinoma of the rectum with squamous cell carcinoma of a retrorectal cyst: report of a case and review of the literature.

Retrorectal cysts are rare congenital anomalies which are more common in females. Rarely, malignant transformation can occur in these cysts. We report here the case of a middle-aged man who had synchronous presentation of adenocarcinoma of the rectum and squamous cell carcinoma in a retrorectal cyst. The patient presented with rectal bleeding and constipation, and underwent abdominoperineal resection and complete excision of the cyst. Postoperative histopathological examination showed adenocarcinoma of the rectum and squamous cell carcinoma of the cyst. The patient received adjuvant chemotherapy and after 18 months of follow-up is free of any local or metastatic disease. Synchronous occurrence of rectal cancer with carcinoma in a retrorectal cyst has not been previously reported in the literature in English.