Schwannoma of the Tongue – A Rare Clinical Entity
1Department of Oral Medicine and Radiology, Rajah Muthiah Dental College, Chidambaram, India
2Department of Oral and Maxillofacial Surgery, Karpaga Vinayaga Institute of Dental sciences, Chennai, India
3Junior Consultant, J.R Dental Care, Chidambaram, India
Schwannoma is a nerve sheath tumour originating from the Schwann cell of nerve sheath. We present case report of a 30 year old female who presented with a swelling on the right lateral border of the tongue since 1 ½ years with notable increase in size for past two months. The swelling was a solitary, mobile, well defined mass, firm in consistency. It was associated with constant irritation from the palatally placed lower right canine. Regional nodes were not palpable. A provisional diagnosis of traumatic fibroma was made. The patient underwent complete enucleation with primary closure. Histological examination after surgical excision revealed schwannoma. The patient had an uneventful postoperative recovery. There was no recurrence after the removal of the mass during the past 2 years of follow up.
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Keywords: schwannoma, tongue swelling, intra-oral swelling, benign
International Journal of Dental Sciences and Research, 2013 1 (3),
Received September 30, 2013; Revised November 15, 2013; Accepted December 09, 2013Copyright: © 2013 Science and Education Publishing. All Rights Reserved.
Cite this article:
- Jayaraman, Venkatesh, Balaguhan Balasubramanian, and Rajakumari Senthivelu. "Schwannoma of the Tongue – A Rare Clinical Entity." International Journal of Dental Sciences and Research 1.3 (2013): 53-55.
- Jayaraman, V. , Balasubramanian, B. , & Senthivelu, R. (2013). Schwannoma of the Tongue – A Rare Clinical Entity. International Journal of Dental Sciences and Research, 1(3), 53-55.
- Jayaraman, Venkatesh, Balaguhan Balasubramanian, and Rajakumari Senthivelu. "Schwannoma of the Tongue – A Rare Clinical Entity." International Journal of Dental Sciences and Research 1, no. 3 (2013): 53-55.
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Schwannoma is a benign, encapsulated slow growing tumour of perineural sheath that is derived from Schwann cell of the nerve sheath . Schwann cell forms myelin sheath around nerve membranes. They help to transmit messages to and from the brain and spinal cord and the rest of the body. Schwannoma typically develops along nerves of head and neck region .
Schwannomas in the head and neck region constitute about 25% of all the extracranial schwannomas; among those, only 1% show an intraoral origin, and the tongue is the most common site [2, 3]. The intraoral lesions have a predilection for the tongue, followed by the palate, floor of mouth, buccal mucosa and mandible4. In the tongue, the base of tongue is commonly affected and the tip is the least affected part . Oral Schwannoma occurs approximately equally in males and females . It is more often found in the second and third decades of life. We present a case of Schwannoma of the lateral border of tongue.
2. Case Report
A 25 year old female presented with a slow growing painless swelling on the right side of the tongue for past 1 ½ years with history of rapid growth for the past two months. There was no history of pain or bleeding. Intraoral examination revealed a 3 cm x 2 cm smooth mobile mass on the right lateral border of the tongue. The margins were well circumscribed and the swelling was firm in consistency. There was constant irritation by the supraerupted lower right canine. Regional nodes were not palpable. The clinical impression was traumatic fibroma of the tongue. Blood investigations were normal. The mass was totally excised surgically. Histological examination revealed Schwannoma of the tongue. No recurrence was noted after the removal of the mass.
Histopathology report of the swelling exhibited tissue made up of interlacing bundles of spindle cells white hyperchromatic spindle nuclei and indistinct cytoplasm resembling Schwann cells. Antoni type B were predominant with few focal Antoni type A areas showing nuclear palisading. Few verrucoy bodies were also seen throughout the section. The periphery shows a thick well formed capsule. It was suggestive of Schwannoma.
Schwannoma typically develops along the nerves of head and neck region. Although the etiology  is unknown, it is believed that the lesion arises from proliferation of Schwann cells at a point inside the perineurium, which causes displacement and compression of the surrounding normal nerve. Oral Schwannoma occur approximately equally in males and females, are more often found in the second and third decades of life . Although Schwannoma account for just over 1% of benign tumours reported in the oral cavity, they are the most commonly encountered nerve sheath tumours in this location. The intraoral lesions have a predilection for the tongue, followed by the palate, floor of mouth, buccal mucosa and mandible . Schwannoma developing around eighth cranial nerve is known as acoustic neuroma or vestibular Schwannoma. Schwannomatosis is a rare inherited disorder involving multiple Schwannoma of head neck and limb region.
The disease is usually asymptomatic. Pain and paraesthesia sometimes occur due to pressure against the surrounding structures. Intraoral lesions usually present as slow growing masses in the sublingual region or the ventral or dorsal aspect of tongue. Neurological weakness of the tongue may or may not be present [5, 10]. In vestibular Schwannoma the symptoms are deafness, tinnitus, loss of balance and facial paralysis. In perineal Schwannoma bowel and bladder problems arise. Differential diagnosis to be considered in a slowly growing and macroscopically circumscribed mass of the tongue are lipoma, hemangioma, eosinophilic granuloma, epidermoid and dermoid cysts, mucocele, epithelial hyperplasia, granular cell tumor, benign salivary gland tumors, rhabdomyoma, leiomyoma, lingual thyroid and lymphangioma [8, 9].
Imaging techniques such as CT and MRI  are used to locate the extension of the tumour. MRI allows an accurate measurement of tumor size and precise localization in relation to other structures. On MRI, tongue schwannomas appear isointense to muscle on T1-weighted images and homogenously hyperintense on T2-weighted images. Moreover, these tumors usually appear smooth, well demarcated, and do not invade the surrounding musculature.
Histological examination  reveals characteristic Antoni A and Antoni B patterns. Antoni type A consists of closely packed Schwann cells that form bundles or are arranged in rows with pallisading, elongated nuclei. Free bands of amorphous substance between rows of nuclei constitute the Verocay bodies. Antoni B shows loosely arranged less elongated cells in a meshwork of reticulum fibers and microcysts. In addition to these characteristic patterns, diagnosis is aided by immunohistochemical  markers, S-100 and Leu 7, which support the Schwann cell nature of these tumors. Radiograph will be useful to identify central bone lesion involving mandible. There will be considerable bone destruction with cortical bone expansion. Treatment of Schwannoma is complete surgical excision. Radiotherapy is not useful. The goal of surgical therapy is complete resection in a way to avoid recurrence. Schwannoma does not undergo malignant transformation.
Schwannoma should be considered in the differential diagnosis when observing a tumor in the oral cavity. Any painless nodule in the head and neck region must be investigsted to exclude schwannoma. The definitive preoperative diagnosis could only be carried out with a biopsy and histopathological study. The treatment consists of surgical excision by transoral resection in a manner that precludes recurrence and avoids causing morbidity of tongue function. The chance of malignant transformation of these tumors is exceedingly unlikely.
List of abbreviations
CT- computed tomography
MRI- magnetic resonance imaging
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