Schwannoma is a benign, slow-growing tumor of the peripheral nerves. Though approximately 25–40% of all schwannomas occur extracranially in the head and neck region, just over 1% of schwannomas are reported in the oral cavity Citation[1], Citation[2]. The mobile portion of the tongue is the most common site followed by the palate, floor of mouth, buccal mucosa, lips, and jaws Citation[3]. According to some series, in contrast to the neurofibroma, which tends to be more frequent in young children Citation[4] the schwannoma is more common in adults. It is most frequently diagnosed in the 25–55 year age group. There is no gender predilection.
A 45-year-old woman presented with swelling over left side of tongue during the last five years. There was no history of pain or bleeding. Her only complaint was mild discomfort at the site of swelling. The swelling was over left posterolateral aspect of tongue about 2.0×3.0×3.0 cm. The swelling was smooth and globular. There was no cervical lymphadenopathy. Contrast enhanced computerized tomography (CECT) revealed a heterogenous lesion in the posterior part of tongue on left side. The imageological impression was possible malignant lesion. The fine needle aspiration cytology done in another center suggested a malignant tumor. Intra-operative finding showed the lesion to be 2.0×3.0×3.0 cm, firm, globular mass over the ventral and lateral surface of tongue. Local excision of the mass was done without any complication.
On gross examination the lesion was 2.0×1.7×1.7 cm, globular and encapsulated. Cut section of the mass revealed yellowish areas and focal hemorrhagic areas. Microscopically the lesion was circumscribed and present below the stratified squamous epithelium showing presence of both Antoni type A and Antoni type B areas. Antoni A area showed fascicles of spindle-shaped Schwann cells around numerous Verocay bodies, which are acellular, eosinophilic areas, surrounded by palisaded spindled cells with blunt, elongated nuclei. There was no significant mitotic activity, pleomorphism or hyperchromasia. The Antoni type B composed of less cellular and more randomly arranged spindle cells in a loose, myxomatous stroma. Immunohistochemistry with s-100 showed positivity in the tumor cells.
Wright and Jackson Citation[3] reported 146 cases of schwannoma of the oral cavity soft tissue. Schwannoma occurs rarely in the oral cavity and produce symptoms varying from slight hypoesthesia to vague paresthesia. The final diagnosis is always made after a definitive histological examination. Lipomas, hemangiomas, eosinophilic granuloma, epidermoid and dermoid cysts, epithelial hyperplasia, granular cell tumor, leiomyoma, lymphangioma, are included in the differential diagnosis of schwannoma Citation[1]. Differential diagnosis also must include malignant tumors (relating to the speed of growth and clinical appearance).
The treatment for schwannoma is surgical excision of the lesion and usually enucleation of the mass is uncomplicated. Recurrence after excision of schwannoma is rare. Malignant change has been reported, however this is an extremely rare phenomenon.
We would like to add another case of schwannoma of the tongue to the existing published cases, so that this should be considered in differential diagnosis.
References
- Harada H, Omura K, Maeda A. A massive pleomorphic adenoma of the submandibular salivary gland accompanied by neurilemmoma of the neck misdiagnosed as malignant tumor: Report of a case. J Oral Maxillofac Surg 2001; 59: 931–5
- Pfeifle R, Baur DA, Paulino A, Helman J. Schwannoma of the tongue: Report of 2 cases. J Oral Maxillofac Surg 2001; 59: 802–4
- Wright BA, Jackson D. Neural tumors of the oral cavity. A review of the spectrum of benign and malignant oral tumors of the cavity and jaws. Oral Surg Oral Med Oral Pathol 1980; 49: 509–22
- Shklar G, Meyer I. Neurogenic tumors of the mouth and jaws. Oral Surg Oral Med Oral Pathol 1963; 9: 1075–93