Cylindroma-like basaloid anal cancer presenting as a large pelvic mass in a patient with ulcerative colitis.

Basaloid cancers of the lower gastrointestinal tract are rare. The lack of mucosal involvement of this type of tumor is uncharacteristic and, to our knowledge, has not been described. In addition, the cylindroma-like appearance of this cancer has only a few examples in the literature. A 51-year-old male presented to us with a history of ulcerative colitis (UC) and obstruction of the anal canal. Imaging and colonoscopy revealed an entirely extraluminal tumor. Percutaneous biopsy yielded a diagnosis of cylindroma-like basaloid carcinoma of the anal region. Neoadjuvant chemotherapy and radiation resulted in stable disease by RECIST criteria. Surgical planning ensued, which led to R0 resection of the tumor, total colectomy and end ileostomy for his UC, and reconstruction of the perineal defect with a rectus myocutaneous flap. Surveillance at 6 months demonstrated no evidence of disease.