A 26-year-old man was admitted to hospital because of lower quadrant pain. Colonoscopy showed a polypoid lesion (0- Ip: protruded, pedunculated)in the cecum. Endoscopic biopsy revealed a tubular adenoma with severe atypia. Laparoscopy- assisted ileocecal resection was performed, as the diameter of the tumor made colonoscopic treatment difficult. Appendiceal intussusceptions were found in the excised specimen. The tumor was mucosal in origin. The patient remained cancer-free after the surgery.