Perirectal Mucinous Adenocarcinoma After Subtotal-Colectomy for Crohn's Disease: A Case Report.

Colorectal carcinoma (CRC) represents the third most common cancer and the second highest cause of cancer-related death in the United States. CRC is particularly prevalent in patients with underlying inflammatory bowel disease. Adenocarcinoma represents more than 90% of new CRC diagnoses. The mucinous subtype of colorectal adenocarcinoma is found in approximately 10-20% of all colorectal cancer patients and is most frequently located in the proximal colon. We report a case of mucinous adenocarcinoma arising from the rectal stump of a patient who had previously undergone subtotal-colectomy with end ileostomy for Crohn's disease. She initially presented with gradually worsening chronic abdominal pain and gelatinous rectal discharge. She was found to have a complex cystic lesion communicating with her Hartman's pouch. She ultimately underwent a completion proctectomy, radical hysterectomy, and bilateral salpingo-oophorectomy in conjunction with gynecology oncology. To the best of our knowledge, this case represents the first description of a perirectal mucinous adenocarcinoma arising in a patient after subtotal-colectomy for Crohn's disease.