Mucosal Schwann cell “Hamartoma”: A new entity?

Abstract

Schwannoma is a well-described, benign nerve sheath tumor of the soft tissue, but is rare in the gastrointestinal tract. Gastrointestinal schwannomas are often incidentally discovered as small polypoid intraluminal lesions. In this report, we describe the clinicopathologic and immunohistochemical features of a distinctive neural mucosal polyp composed of a diffuse cellular proliferation of uniform bland spindled cells in the lamina propria that entraps the colonic crypts. Immunohistochemical analysis revealed strong and diffuse positivity for the S-100 protein. To avoid confusion of these solitary colorectal polyps containing pure spindled Schwann cell proliferation in the lamina propria with neural lesions that have significant association with inherited syndromes, it is better to use the designation "mucosal Schwann hamartoma".

Mucosal Schwann-Cell Hamartoma Diagnosed by Using an Endoscopic Snare Polypectomy

“…Plexiform neurofibromas are a pathognomonic sign of NF1, and a solitary neurofibroma is rare [1, 5]. A solitary neurofibromal colonic polyp without NF1 is very rare and has been reported in only 1 case in Korea and in 31 cases abroad [1-3, 6-8]. Recently, Gibson and Hornick [1] analyzed 26 cases of solitary colorectal polyps with pure Schwann-cell proliferation that were different from the neurofibromas found in NF1 and were not associated with inherited syndromes.…”

“…The histological differential diagnosis of a mucosal Schwann-cell hamartoma includes a gastrointestinal stromal tumor, a neurofibroma, a mucosal neuroma, a ganglioneuroma, and a mucosal schwannoma [1-3]. Gastrointestinal stromal tumors are frequently detected in the form of subepithelial tumors in the stomach or small intestine, but are rarely found in the colon.…”

“…The lesion shows strong and diffuse immunoreactivity for the S-100 protein. Although a proliferation of Schwann cells is observed, mucosal Schwann-cell hamartomas can be differentiated from schwannomas with no specific findings of verocay bodies, Antoni A and Antoni B regions, lymphoid cuffs, and lymphoid infiltrations [3]. We report, with a brief literature review, a case of a mucosal Schwann-cell hamartoma that was detected incidentally during colonoscopy for a routine check-up and was removed by using a snare polypectomy.…”

Gastrointestinal Schwannoma: An Unusual Colonic Lesion Mimicking Adenocarcinoma

“…Gross features often do not enable the distinction between schwannomas and GIST (6). Differentiation requires detailed histological evaluation to investigate characteristic features of schwannoma that include the presence of a lymphoid peripheral cuff with the absence of encapsulation and degenerative changes (14). It is believed that the lymphoid cuff is the result of cytokines secreted by the tumour cells, inducing chemokinesis of the lymphocytes (15).…”

Rectal Mucosal Schwann-Cell Hamartoma: A Case Report and Literature Review

“…Although there is a proliferation of Schwann cells and S-100 positivity, mucosal Schwann cell hamartomas are different from schwannomas in that they lack Verocay bodies, Antoni A and Antoni B areas, lymphoid infiltrations, and lymphoid cuffs. Neurofibromas and ganglioneuromas can also be distinguished from Mucosal Schwann cell hamartomas on the basis of the presence of fibroblasts with axons and ganglion cells, respectively [1,4,5].…”