[A case of cap polyposis complicated with idiopathic retroperitoneal fibrosis].

An optimal treatment for cap polyposis has not been established. Several treatment approaches, including anti-inflammatory agents, antibiotics, immunomodulators, and endoscopic therapy have been described. Surgical resection of the affected colon and rectum may be indicated for patients with persistent disease. Repeat surgery is indicated in cases of recurrence after surgery. However, symptomatic polyposis may still recur, and spontaneous resolution of cap polyposis is possible. We report a case of recurrent cap polyposis complicated with retroperitoneal fibrosis after inadequate low anterior resection with a positive resection margin. Surgical approaches for the treatment of cap polyposis should be carefully considered before treatment.