Case Report of a Polypoid Ganglioneuroma and Retrospective Case Review

Abstract

Background: Polypoid ganglioneuromas (GN) are small, sessile or pedunculated polyps within the category of intestinal ganglioneuromas. These benign hamartomatous polyps are characterized by the presence of ganglion cells, nerve fibers, and supporting cells. GN of the intestinal tract can be classified as polypoid GN, ganglioneuromatous polyposis, or diffuse ganglioneuromatosis. Colonic polypoid GN is a rare finding and diagnostic confirmation is based on positive immunohistochemistry staining for the S-100 protein. Case: An 85-year-old male Vet was referred for a routine colonoscopy for cancer screening and as part of an anemia work-up. He was clinically asymptomatic. Physical examination was unremarkable. Colonoscopy revealed internal hemorrhoids, sigmoid diverticulosis, and one diminutive sigmoid polyp at 35 cm; it was removed in toto with cold biopsy forceps. The polyp had no defining features on narrow band imaging (NBI) to differentiate that from a hyperplastic or an adenomatous polyp. Routine H&E staining revealed scattered ganglion cells within spindle cell areas. The polyp upon immuno-histochemistry staining was positive for the S-100 protein. The pathological diagnosis was mucosal neuroma. This was an incidental finding and not thought to be a contributing factor to the patient's anemia. We searched the database of 102,371 colonic polyp biopsies from 2000 to 2012 at the Audie L. Murphy VAH and found only six reported cases of confirmed GN. (Incidence of 0.00005861 or about 6 cases/100,000) Conclusion: Intestinal GN is a rare finding on colonoscopy, but may surprise the clinician upon pathology report review of a removed polyp that resembled a hyperplastic or adenomatous polyp by standard white light optical endoscopy. There are few reports of this entity in the literature. When encountered in clinical practice, polypoid GNs frequently resemble hyperplastic or adenomatous polyps on optical endoscopy. S-100 immunochemical staining can differentiate these from the most frequently found common polyp types. Intestinal GNs are not considered to be pre-malignant and require no further clinical follow-up. Unlike diffuse ganglioneuromatosis, polypoid GN are not associated with MEN IIB or Neurofibromatosis 1.