Large small cell carcinoma of anorectal canal.

Neurofibromatosis type-1 (NF1), also known as Von Recklinghausen disease, is an autosomal dominant disorder with incidence of one per 4000. Neurofibromas are benign, heterogeneous, peripheral nerve sheath tumors coming up from the connective tissue of peripheral nerve sheaths, particularly the endoneurium. Visceral involvement in disseminated neurofibromatosis is considered rare. Neurofibroma occurs most frequently in the stomach and jejunum, but colon and anorectal canal may also be involved. Gastrointestinal neurofibromas may lead to bleeding, obstruction, intussusception, protein-losing enteropathy and bowel perforation. We encountered a case of diffusely involving the anorectal area by huge neurofibroma, which resulted in pelvic pain with watery diarrhea and urgency.