Diagnosis and Discussion
Diagnosis
Incidental appendiceal ganglioneuroma
Discussion
Ganglioneuromas (GN) of the gastrointestinal tract (GIT) are benign mesenchymal neoplasms composed of Schwann cells and ganglion cells. Three forms of GN are recognized in the GIT: sporadic, syndromic, and diffuse. The majority of GIT GN are sporadic and arise as solitary polyps in the colon and rectum. In contrast, syndromic GN (ganglioneuromatous polyposis) occur as multiple polyps in patients with multiple endocrine neoplasia type 2B, Cowden disease (PTEN hamartoma syndrome), tuberous sclerosis, and familial adenomatous polyposis. Lastly, diffuse ganglioneuromatosis is characterized by a transmural ganglioneuromatous proliferation, also associated with the aforementioned syndromes.
Histologically, a GN is characterized by bland, spindled cells in a fibrillary matrix admixed with scattered aggregates of ganglion cells. The lesion tends to splay or separate the colonic crypts. Immunohistochemical stains show the spindled cells are diffusely positive for S-100 protein and the ganglion cells are positive for synaptophysin, neuron-specific enolase, and neurofilament protein. The histologic differential diagnosis includes mucosal Schwann cell hamartoma and intestinal perineurioma. Schwann cell hamartomas often present as polypoid lesions in the colon and are microscopically characterized by bland spindled cells confined to the mucosa and positive for S-100 protein, but lacking ganglion cells. Intestinal perineuriomas present as polyps in the distal colon and are seen histologically as bland spindled cells in a whorling pattern, often associated with a serrated polyp. In contrast to GN and Schwann cell hamartomas, perineuriomas are negative for S-100 and positive for GLUT-1, EMA, and claudin-1.
There are limited cases describing appendiceal GN in the literature. Of these, most describe syndromic GN. To our knowledge, there are only two case reports of solitary appendiceal GN, one of which presented as acute appendicitis. It appears that solitary, incidental GN involving the appendix, as seen in our case, are extremely rare.
References
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