Diagnosis and management of hypoglossal nerve-derived schwannoma in the floor of mouth: a case series

Abstract

Background Schwannomas or neurilemmomas are well-encapsulated, benign, solitary, and slow-growing tumors that originate from Schwann cells of the nerve sheath. Extracranial schwannoma is reported to have a relatively high incidence in the tongue while an extremely low incidence in the floor of mouth. In the current study, we presented the first case series of hypoglossal nerve-derived schwannoma in the floor of mouth in Asia. Methods A retrospective study of 9 surgical cases of hypoglossal nerve-derived schwannoma in the floor of mouth was performed. The patient and tumor characteristics were evaluated by physical, radiological and pathological examination. Details of operation and complications were also recorded. Results Hypoglossal nerve-derived schwannoma in the floor of mouth showed a well-defined boundary with a firm texture, smooth surface and good mobility on palpation. The median maximum diameter of the tumors was 4.3 cm (range 2.8–7.0 cm). The median operative time and bleeding volumes were 89.4 min (range 47–180 min) and 99.2 mL (range 15–200 mL), respectively. All cases received complete surgical excision. Conclusion In this study, we presented the diagnosis and management of hypoglossal nerve-derived schwannoma in the floor of mouth for the first time in Asia. The study provided us with a recommendation for consideration of the diagnosis of hypoglossal schwannoma when a patient presents with a mass in the floor of mouth.

Case of submandibular schwannoma and review of literature

“…A 10-year review of Schwannoma cases across two tertiary centres in Brazil documented only 1 of 12 cases of intra-oral schwannomas occurring in the floor of mouth [ 6 ]. A literature search of the terms “sublingual schwannoma, floor of mouth schwannoma, Sublingual neurilemmoma” from 2000 to 2022 in English yielded 15 cases, 1 of the mylohyoid nerve, 10 of the hypoglossal nerve, 3 within the submandibular gland, and 1 unspecified [ 4 , 5 , [7] , [8] , [9] ].…”

“…Although associated with low rate of recurrence, excision is not without its risks in otherwise asymptomatic patients and is highly dependent on the specific location of the individual lesion and proximity to adjacent structures [ 6 ]. In a surgical review of 9 cases of hypoglossal nerve schwannomas, 3 cases of asymptomatic presentations underwent complete excision, of which 1 case required transection of the main hypoglossal nerve trunk, resulting in hypoglossal nerve palsy [ 4 , 8 ]. A recently published consensus guideline on management of Schwannomatosis recommends surgical excision only in symptomatic individuals, where surgery is unlikely to result in neurological deficits [ 13 ].…”

“…Symptoms and presentation relate to local mass effect dependent on the location and size of the lesion [ 1 ]. Detection of these lesions is often incidental, owing to their slow-growing nature and frequently deep-seated location [ 3 , 4 ]. As such, imaging is often critical and superior to clinical evaluation [ 1 , 2 ].…”

Extracranial Hypoglossal Schwannoma: Case Report and Literature Review

“…It is also important to have a thorough understanding of the hypoglossal nerve's anatomy, particularly its extracranial portion, in each individual case (3,12). Although MRI is considered the most effective imaging method for detecting masses and assessing their extent, in some cases, such as ours (2,8), patients undergo CT scans. Schwannomas are visible on CT scans as well-defined tumors with low or soft tissue attenuation and homogeneous or heterogeneous contrast enhancement, depending on the predominance of Antoni B fibers (1,8,12).…”

“…Schwannomas are solitary, benign, slow-growing, and wellencapsulated neurogenic neoplasms originating from the myelin-producing Schwann cells of the peripheral nerves (1)(2)(3)(4)(5)(6). They can involve the cranial nerves, such as V, VII, X, XI, and XII or sympathetic and peripheral nerves (7)(8)(9)(10)(11). Approximately 25-45% of extracranial schwannomas are located in the head and neck region (7-9, 12, 13).…”