Tongue Schwannoma Case Report Samuel Fleisher, B.A.; Scott M. Peters, D.D.S.; Louis Mandel, D.D.S.
ABSTRACT Schwannomas are uncommon benign neoplasms derived from the nerve sheath’s schwann cells. The rare few seen in the oral cavity usually involve the tongue, and because they are encapsulated, they can be bluntly dissected from the tongue’s soft-tissue bed. The schwannoma, or neurilemmoma, is an uncommon tumor derived from the myelin-producing schwann cells of the nerve sheath. It is a benign, slow-growing, painless neoplasm that can originate from the sheath of any nerve (cranial, autonomic, peripheral). The optic and olfactory nerves are cranial nerves that are exceptions because of their lack of a schwann cell sheath.[1] Schwannomas develop equally in both sexes.[2-4] The age range of 30 to 50 years is considered the most likely period for this unusual tumor’s occurrence.[5,7] The schwannoma is a solitary, well-circumscribed growth that tends to push adjacent structures aside as it proliferates. Reportedly, 25% to 45% of these tumors involve the head and neck region,[1,7-9] with as few as 1% of them occurring intraorally.[2,3,5,6] The tongue represents the most common intraoral location, followed by the palate, buccal mucosa and mouth floor.[5,6,10,11] Besides these soft-tissue locations, the tumor can occur intraosseously, usually in the posterior mandible.[7,9] The oral as-
32 APRIL 2021 The New York State Dental Journal ●
pect of the tongue is more frequently involved than the tongue base. The mean size for a schwannoma in the anterior tongue is approximately 2 cm,[2,4,8] while those posteriorly located tend to be larger. Although schwannomas in the anterior tongue cause no symptoms, dysphagia, dyspnea and dysphonia can occur with those larger schwannomas that are located in the tongue base.[1] Tongue schwannomas probably arise from the sheath around the hypoglossal nerve.[3] However, because of this nerve’s close proximity to the glossopharyngeal and lingual nerves, the exact nerve of origin is difficult to ascertain.[8] When establishing a clinical differential diagnosis for a submucosal tongue nodule, one must consider benign tumors, such as the granular cell tumor (GCT), the neurofibroma (NF) and the schwannoma. All three entities are categorized as benign neural tumors, with the NF representing the most common peripheral nerve tumor. Because solitary lesions are clinically indistinguishable, a biopsy is required for the definitive diagnosis. Of importance, the presence of multiple NFs may be seen in patients with NF1 (von Recklinghausen disease of the skin).[3,5,11] Schwannomas are usually absent from NF1, but may be a component of other syndromes, such as neurofibromatosis II (NF2) and schwannomatosis. Patients with NF1 are at increased risk for development of a malignant peripheral nerve sheath tumor following a malignant transformation of a NF. This malignant transformation is rarely, if ever, seen in cases of isolated (non-syndromic) NFs. With re-
