|Year : 2018 | Volume
| Issue : 4 | Page : 202-204
Schwannoma of the base of the tongue mimicking fibroma
Sukhvinder Singh Rana, Neera Ohri
Department of Dentistry, Dr. RPGMC, Kangra, Himachal Pradesh, India
|Date of Web Publication||18-Dec-2018|
Ohri Market, Kangra - 176 001, Himachal Pradesh
Schwannoma is a slow-growing benign tumor of the nerve sheath. It originates from the Schwann cell of the peripheral, autonomic, and cranial nerve. It is usually a single, circumscribed, firm, painless lesion of variable size. 25%–40% of all schwannomas are considered to affect the head and neck region, with the parapharyngeal space being the most common location. Only 1% of cases are intraoral. The treatment of choice is surgical excision of the tumor. Schwannomas do not show recurrence if completely excised. We report a case of schwannoma of the base of the tongue mimicking fibroma.
Keywords: Fibroma, schwannoma, tongue
|How to cite this article:|
Rana SS, Ohri N. Schwannoma of the base of the tongue mimicking fibroma. SRM J Res Dent Sci 2018;9:202-4
| Introduction|| |
The schwannoma also known as neurilemmoma or perineural fibroblastoma is a rare benign neural tumor arising from the neural sheath's Schwann cells of the peripheral, cranial (except the optic and olfactory nerves), or autonomic nerves.
25%–40% of all schwannomas are considered to affect the head and neck region, with the parapharyngeal space being the most common location. Only 1% of cases are intraoral. The intraoral lesions show a predilection for the tongue, followed by the palate, buccal mucosa, lip, and gingiva. Schwannomas of the tongue typically present in the third decade of life and display no gender predilection. The treatment of choice is surgical excision of the tumor most commonly by transoral approach.
The treatment of choice is surgical excision of the tumor. Schwannomas do not show recurrence if completely excised. We report a case of schwannoma of the base of the tongue.
| Case Report|| |
A 17-year-old young male patient was reported to our department with a small swelling on the base of the tongue [Figure 1]. He noticed this swelling two month back. His only symptom was he feels discomfort with this swelling. During oral examination, a 12 mm × 10 mm mass was seen on the base of the tongue. The mass was smooth, firm, non tender, well demarcated, the overlying mucosa was normal. A provisional diagnosis of fibroma was made and swelling was planned for surgical excision. Excision of the mass was done under local anesthesia by transoral approach. Soft-tissue specimen was sent for histopathological examination. The biopsy report revealed a schwannoma [Figure 2].
| Discussion|| |
Schwannoma is a slow-growing benign tumor of the nerve sheath. It originates from the Schwann cell of the peripheral, autonomic, and cranial nerves. It is usually a single, circumscribed, firm, painless lesion of variable size.
In 1910, Verocay first described a group of neurogenic tumors that he referred to as “neurinomas.” In 1935, it was proposed that these tumors arose from the nerve sheath elements and they were termed “neurilemmomas.” It was now felt that the Schwann cell is the common precursor for most nerve sheath tumors.
Head and neck schwannoma can arise from any cranial nerve, except olfactory and optic nerves, as they are extensions of white matter from the brain. More than 90% of intracranial schwannomas involve the eighth cranial nerve, more commonly superior vestibular division of the nerve. In decreasing order, trigeminal, glossopharyngeal, and vagus nerves also form schwannoma in both intra- and extracranial parts. Schwannomas rarely form on the hypoglossal nerve.
Embryologically, Schwann cells arise during the 4th week of development from a specialized population of ectomesenchymal cells of the neural crest, which then detach from the neural tube and migrate into the embryo. Schwann cells form a thin barrier around each extracranial nerve fiber and wrap larger fibers with an insulating membrane, myelin sheath, to enhance nerve conductance. As nerves exit the brain and spinal cord, there is a change between myelination by oligodendrocytes and myelination by Schwann cells. Schwannomas arise when proliferating Schwann cells form a tumor mass (unknown etiology), encompassing motor and sensory peripheral nerves. Only 50% of these tumors have a direct relation with a nerve.,
Histologically, schwannomas display several features. Virtually, all of these tumors are encapsulated. Beneath this capsule, two main patterns are seen intermingled, but sharply defined from each other. The first pattern is referred to as Antoni type A, which consists of closely packed Schwann cells that form bundles or are arranged in rows with palisading, elongated nuclei. Free bands of amorphous substance between rows of nuclei constitute the Verocay bodies. The second pattern is known as Antoni type B and is composed of very loosely arranged Schwann cells set in a meshwork of reticulum fibers and microcysts.
Schwannomas in the head and neck regions constitute 25% of all extracranial schwannomas, but only 1% show intraoral origin. The intraoral lesions show a predilection for the tongue, followed by palate, buccal mucosa, lip, and gingiva. Leu and Chang in their review of 52 cases of neurilemmomas originating in the head and neck region found that 25 schwannomas originated in the scalp, face, and external auditory canal, 18 in the neck, and only 9 schwannomas in the oral or nasal cavity. Lopez and Ballestin in their study of nine intraoral schwannomas found three schwannomas in vestibule, two each in the tongue and palate and one each in the floor of the mouth and lower lip.
The signs and symptoms of these tumors depend on the location. They usually are asymptomatic. If they occur on the base of the tongue or come in the way of breathing or swallowing, they might cause dyspnea or dysphagia. Otherwise, the presenting feature of an intraoral schwannoma is a tumor mass.
All reported cases of schwannomas of the tongue have been treated by surgical excision. The most common approach was the transoral route. This is an obvious choice for approaching these tumors because most are easily accessible via this route. Several other approaches have also been reported to have success, including submandibular, suprahyoid pharyngotomy, and transhyoid approaches. All of these approaches were used for the base of the tongue schwannomas that were deemed difficult to approach by the transoral route. More recently, the use of CO2 laser for excision of a base of the tongue schwannoma has also been reported. The goal of surgical therapy is to complete resection. If this is accomplished, recurrence is rare.
| Conclusion|| |
The schwannoma on the base of the tongue is extremely rare not often encountered in day-to-day clinical practice. Here, we presented a case of a schwannoma of the base of the tongue mimicking fibrous lesion, which was not considered as a possible diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]