Neurinoma or schwannoma is an uncommon benign tumor that arises primarily from the nerve sheath of Schwann cells. About 25% has been reported in head and neck region extracranially, but only 1% in the intraoral origin. Intraorally, the tongue is the most common site followed by the palate, floor of the mouth, lips and buccal mucosa. In review of literature, intraoral schwannoma of the lingual nerve origin has not been reported frequently. So, we present a case of intraoral neurinoma of the lingual nerve.
Schwannoma/neurinoma is a nerve sheath tumor that originates from the Schwann cells of peripheral, cranial, and autonomous nerves. It is a slow growing benign tumor, mostly asymptomatic in nature. It frequently appears as a solitary encapsulated swelling, except the neurofibromatosis type which occurs as multiple lesions [
In the literature, there are reported cases of neurinoma/schwannoma originating from the mylohyoid nerve, hypoglossal nerve, and sublingual gland, but there are a very few literatures on schwannoma originating from the lingual nerve [
A thirty-one-year old female patient reported to the Department of Oral and Maxillofacial Surgery with a swelling in the floor of the mouth for the past two months. The swelling was initially small and gradually reached the present size over two months. On extraoral examination, a diffuse swelling in the left submandibular region was present. On intraoral examination, a single well-defined encapsulated swelling was present in the left side of floor of the mouth (Figure
Intraoral view of well-circumscribed swelling (black arrow) in the left floor of the mouth.
Axial computed tomogram of head and neck showed a dense mass in the left side of floor of the mouth region measuring about 33 mm × 23 mm with a dilated lingual nerve found within the mass (Figures
Axial CT shows dense mass of 3.32 cmm 2.33 cmm in the floor of the mouth.
Axial CT shows lingual nerve (small circle) found within the mass in the left floor of the mouth.
Under general anaesthesia, a mucosal incision was placed over the mass in the left side of the floor of the mouth, the tumor was exposed and dissected safely from the lingual nerve, and excision was carried out by ligating the lingual nerve on the distal and mesial end of the swelling (Figure
Intraoperative picture showing mucosal incision and exposed encapsulated mass (black arrow) in the left floor of the mouth.
(a) Macroscopic picture of well-encapsulated mass measuring 3.5 cm-4 cm-3 cm. (b) Cut surface of specimen shows areas of cystic degeneration inside surrounded by solid area.
(a) Histopathological view of 10x shows Antoni A: cellular region, nuclei palisaded in arrangement around central acellular eosinophilic areas, and Verocay bodies. (b) Histopathological view shows Antoni B: relatively acellular in a loose, myxomatous stroma.
The term “ancient schwannoma” was coined by Ackerman and Taylor as it shows long standing degenerative changes in the benign neural tissues and has a distinctive area of hypocellular tissues [
According to English the literature review, to date a total of only eight cases of ancient schwannoma have been reported. Nakayama et al. reported a maximum diameter of lesion in female patient of 55 mm; Dayan et al. reported ancient schwannoma with a maximum diameter of 31 mm [
Differential diagnosis of the swelling in the floor of the mouth can be a mucocele, ranula, pleomorphic adenoma, or Submandibular gland enlargement. Most of the cases in the floor of the mouth, FNAC is inconclusive as it always gives negative result either when swelling is firm or it gives false results mostly as pleomorphic adenoma of submandibular gland in cases of intraoral schwannoma of submandibular gland [
The clinical and radiological diagnosis will not give reliable results like a histopathological diagnosis. Complete surgical excision and histopathological examination of the excised lesion could be a choice for treatment of an encapsulated mass in the floor of the mouth [
Ancient schwannomas possess four unique features: (1) encapsulated mass with degenerative alterations containing both large cystic and solid areas, (2) mixture of spindle cells with highly cellular (Antoni A) and less cellular myxoid (Antoni B), (3) palisaded nuclear appearance of Schwann cells, (4) and Verocay bodies seen in a cellular eosinophilic zone. Our case is also an ancient schwannoma because it has all the unique features such as the encapsulated mass in the floor of the mouth and excised gross specimen examination shows both large cystic and small solid areas in it; similarly histopathological features show fibrous capsule enclosing proliferation of Schwann cells with Antoni A and Antoni B types of tissue which suggest ancient schwannoma [
Significance of our case is the rapid growth with a maximum diameter of 4 cm, associated with pain and neurosensory disturbance in a shorter duration of two months which is not a unique character of intraoral neurinoma, and this makes our case different from the previously reported cases.
Intraoral neurinoma is not a frequently encountered benign neoplasm and histopathological examination is the only reliable method for diagnosis of submucosal lesion. Malignant transformation of intraoral neurinoma has not been reported yet, so complete surgical excision has a good prognosis for the treatment of intraoral neurinoma. In spite of lack of the literature on the clinical significance of neurosensory disturbances in intraoral neurinoma, we advise that preservation of nerve during complete surgical excision and microsurgical repair of nerve ending play a vital role in recovery and prevention of neurosensory disturbances in the postoperative period.
Ethical approval is not required.
Informed consent was obtained from the patient.
The authors declare that there is no conflict of interests regarding the publication of this paper.