Mucosal Benign Epithelioid Nerve Sheath Tumors

Johns Hopkins Medical Institutions, Weinberg 2242, 401 N. Broadway, Baltimore, MD 21231, USA.
American Journal of Surgical Pathology (Impact Factor: 5.15). 11/2005; 29(10):1310-5. DOI: 10.1097/01.pas.0000162762.03068.7a
Source: PubMed


Mucosal nerve sheath tumors have been well described in the gastrointestinal tract and other mucosal sites. In a series of mucosal biopsies, we have encountered a distinct subset of mucosal peripheral nerve sheath tumors characterized by small epithelioid cells and a benign clinical course. Such epithelioid nerve sheath tumors have been observed as a component of a larger study of colorectal "schwannomas," but herein we describe them in detail. A series of 7 of these lesions detected on mucosal biopsies (6 colonic, 1 bladder) was received by a single large institution in consultation material. The histologic and clinicopathologic features of the cases were reviewed. The mean age at presentation was 58.6 years with a slight female predominance (4 females, 3 males). Five of the colonic lesions were from the left colon and one from the right colon. The bladder biopsy was from the bladder neck. All of the colonic lesions were discovered as small (0.2-1.0 cm) polyps during the time of colonoscopy (3 at the time of routine screening, 2 for the workup of occult blood in the stool). The bladder neck mass was seen on bladder ultrasound after the patient presented with vaginal bleeding. None of the patients had a known history of neurofibromatosis. Histologically, the lesions showed an infiltrative growth pattern and were composed of spindled to predominantly epithelioid cells arranged in nests and whorls. The epicenters of the lesions were located in the lamina propria and extended to the superficial submucosa. The proliferating cells had uniform round to oval nuclei with frequent intranuclear pseudoinclusions and eosinophilic fibrillary cytoplasm. No mitoses were seen. All lesions expressed diffuse S-100 protein, and 3 of 5 lesions stained showed CD34 labeling in supporting cells. All were negative for CD117. All 5 lesions tested were negative for calretenin, while SM31 showed no intralesional neuraxons. One lesion was stained for epithelial membrane antigen and was negative. One lesion was associated with superficial mucosal erosion, and 1 had an inflammatory infiltrate predominantly composed of eosinophils. On follow-up of 5 patients, none has had any symptoms or recurrence of disease. Mucosal epithelioid nerve sheath tumors are a rare entity characterized by prominent epithelioid round to oval cells with an infiltrative growth pattern. These lesions are often discovered incidentally and have a benign clinical course.

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    • "Mucosal neuromas are mainly detected on the lips and the tongue and are very rarely found in the gastrointestinal tract. The lesions are highly associated with multiple endocrine neoplasia, type 2B [10]. Mucosal neuromas, which are composed of hyperplastic bundles of nerve fibers and axons, can be histologically distinguished from a mucosal Schwann-cell hamartoma [1]. "
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    ABSTRACT: Colorectal polyps of mesenchymal origin are a rare group of colorectal disorders. A "mucosal Schwann-cell hamartoma," which is one type of polypoid lesion that originates from the mesenchyme, is a newly-proposed disease entity to be distinguished from the neurofibromas found in type-1 neurofibromatosis. This lesion is composed of pure Schwann-cell proliferation in the lamina propria and shows diffuse immunoreactivity for the S-100 protein. We report a case of a polypoid lesion of the colon with the features of this recently-proposed disease entity.
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    • "This heterogeneous group includes ganglion cells and nerve sheath tumors that have been frequently described as multiple lesions in association with inherited syndrome such as von Recklinghausen's (or type 1) neurofibromatosis (NF-1) [4,5], multiple endocrine neoplasia type 2B (MEN 2B) [6] and Cowden syndrome [7]. Moreover, sporadic forms of these neural lesions have been reported including solitary colonic polypoid ganglioneuroma [8], solitary colonic neurofibroma [9,10], and mucosal benign epithelioid nerve sheath tumors [11]. "
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