An Isolated Colonic Neurofibroma Without Systemic Neurofibromatosis: A Rare Case Report and Literature Review.

BACKGROUND Solitary neurofibromas of the colon are extremely rare and are most often reported in patients with neurofibromatosis type 1 (NF1). Although usually benign, these lesions can rarely undergo malignant transformation, particularly when associated with NF1. Therefore, isolated cases merit careful evaluation and follow-up. CASE REPORT A man in his 70s with a history of benign prostatic hyperplasia presented with recurrent abdominal pain, constipation, and unintentional weight loss of 5 kg over 1 month. Physical examination revealed a firm, non-mobile mass in the right lower quadrant, with no other systemic findings or features suggestive of NF1. Laboratory investigations were within normal limits except for mildly elevated lactate dehydrogenase, while carcinoembryonic antigen was normal. Computed tomography and magnetic resonance imaging demonstrated a cystic lesion arising at the base of the appendix and protruding into the cecum. Colonoscopy revealed a large, smooth polypoid mass, and biopsy showed a spindle-cell lesion of neurogenic origin. The patient underwent an open right hemicolectomy with primary ileocolic anastomosis, due to persistent symptoms and concern for potential complications. Final histopathology confirmed a benign isolated colonic neurofibroma with negative resection margins and a reactive mesocolic lymph node, with no evidence of malignancy. The postoperative course was uneventful. The patient remained asymptomatic, with no recurrence during more than 3 years of follow-up. CONCLUSIONS This case highlights that isolated colonic neurofibroma should be included in the differential diagnosis of nonspecific or submucosal colonic masses. Long-term follow-up is important to monitor for local recurrence, possible malignant transformation, and the later appearance of NF1 features.