Cap polyposis is extremely rare in children. We report a case of an 11-month-old male infant who visited our hospital because of rectal prolapse and small amount of hematochezia lasting several days. He also had an epidermal nevus in the sacral area. Colonoscopy showed erythematous, multilobulated, circumferential, polypoid lesions with mucoid discharge from the rectum. He was diagnosed with ca...