Nerve Sheath Myxoma (Neurothekeoma) of the Gingiva, A Case Report and Review of the Literature

Abstract

Nerve sheath myxoma (NSM) is a benign peripheral nerve sheath tumor that rarely occurs in the oral cavity. Among the 23 reported intraoral cases, no lesion has previously been reported on the gingiva. In this report, we describe the first gingival case of oral neurothekeoma with histopathologic and immunohistochemical characteristics. The patient, a 32 year old female presented with a slowly growing gingival mass diagnosed clinically as an epulis. The lesion was surgically excised. Histopathologically, the lesion presented as a submucosal multinodular mass composed of spindle and stellate-shaped cells with a myxoid background. Immunohistochemically, the tumor cells were sporadically positive for S-100 and NSE and negative for GFAP, EMA, SMA, CD68 and HMB45. The immunoprofile of this lesion confirmed a Schwann cell origin. The lesion was followed up for 10 months with no reports of recurrence.

Intraoral nerve sheath myxoma: Case report and systematic review of the literature

“…Therefore, we believe that only true NSMs were included in our study . Beyond S‐100 expression, the majority of oral NSMs, including the current case, expressed NSE . Few cases ( n = 3) in this systematic review were evaluated for GFAP immunoexpression .…”

“…Although it is clear that NSMs and neurothekeomas are distinct lesions, many articles, even recent published ones, use these 2 terms as synonymous, or still consider them as variants of the same tumor . Moreover, many cases of oral lesions reported under the name NSM did not present immunohistochemical features compatible with this entity, being S‐100 negative.…”

“…Nerve sheath myxoma (NSM) is an uncommon benign peripheral nerve sheath neoplasm first described in 1969 by Harkin and Reed and Scheithauer et al This neoplasm arises most commonly within the dermis and subcutaneous tissues on the face and upper extremities and is extremely rare in the intraoral region . Intraoral NSM was first reported in 1974 by Mincer and Spears and few cases in the oral mucosa were reported so far in the medical literature …”

“…In 1980, Gallager and Helwig introduced the term neurothekeoma in the literature to designate a benign cutaneous tumor, regarded as having a neural origin, which shared many clinical and histological similarities to NSM. Since then, many authors have considered NSM and neurothekeoma as variants of the same tumor, being the NSM, the myxoid, or hypocellular variant and the neurothekeoma the cellular variant . Although currently, it is known that they are distinct lesions with different origins and distinct morphological and immunohistochemical features, the terms NSM and neurothekeoma have been erroneously used interchangeably, causing great confusion.…”

Oral nerve sheath myxoma: a rare and unusual intraoral neoplasm

“…The etiology of NSM is unknown, although as many occur in areas subject to trauma, it has been proposed that traumatic injury may play a role . Aside from fibroepithelial polyps, differential diagnosis may include a mucocele, lipoma, fibrolipoma, schwannoma, and a neurofibroma . Histologically, the primary differential diagnosis is a neurothekeoma, which may clinically be indistinguishable from a NSM .…”