Base of tongue schwannoma.
The differential diagnosis included leiomyoma, rhabdomyoma, lymphangioma, hemangioma, epidermoid cyst, lipoma, granular cell tumor, tumors of the salivary gland, and malignancy. Findings of fine-needle aspiration cytology of the lesion were inconclusive. Magnetic resonance imaging (MRI) revealed a well-circumscribed, rounded lesion in the right half of the tongue, which was hypointense on T1-weighted and hyperintense on T2-weighted MRI (figure 1). There was splaying of the tongue muscles with no infiltration. A presumptive diagnosis of a benign lesion was made, and the patient underwent an excision biopsy of the lesion transorally.
The postoperative period was uneventful. Histopathology revealed an encapsulated tumor composed of hypercellular Antoni A areas and hypocellular Antoni B areas. Antoni A areas were composed of spindle-shaped cells forming Verocay bodies. Many dilated and congested vessels were also seen (figure 2, A). Hence, a final diagnosis of schwannoma was made. This was confirmed by S-100 immunocytochemistry (figure 2,B). The patient has been in regular follow-up for the past year, with no untoward incident to report.
Schwannoma is a tumor of neuroectodemal origin, arising from the Schwann cells of the neural sheath of motor and sensory nerves. Although 25 to 40% of all schwannomas occur extracranially in head and neck region, approximately 1% of schwannomas are seen in the oral cavity. (1,3) The tongue is the most common location for intraoral schwannomas to occur; however, it is quite unusual to see a schwannoma at the base of the tongue. (1,3) In fact, of the approximately 130 cases of tongue schwannoma reported in the English-language literature, only 19 cases have been reported at the base of tongue. (2) Although the etiology of these tumors is obscure, it is noteworthy that only 50% of them have a direct relation with a nerve. (4)
Lesions in the posterior part of tongue are more likely to present with clinical features than anterior tongue lesions. Of the 19 reported cases of tongue base schwanomas, 12 (63%) were symptomatic, presenting with clinical features such as pain, dysphagia, or voice change. (2) These lesions can also present with severe symptoms, such as respiratory distress, warranting tracheostomy. (4) Anterior tongue lesions usually present as asymptomatic swellings.
Schwannoma is a histopathologic diagnosis, but radiology aids in delineating the lesion and making a presumptive diagnosis. MRI is regarded as the gold standard. (1,4) On Tl-weighted images, these lesions appear hypointense or isointense relative to the tongue muscle. With T2-weighted images, the tumor is homogenous in signal intensity, with cystic or degenerative changes. The use of CT is less than ideal because it can be limited by bone artifacts, especially case involving smaller lesions.
Compete excision of the tumor is the treatment of choice. For most lesions of the toungue base, a transoral approach has been used. We, too, had excellent results with that approach. However, submandibular, suprahyoid pharyngotomy and transhyoid approaches have been used for schwannomas at the tongue base that are deemed difficult to approach transorally. (1,3)
Gautam Bir Singh, MS; Rubeena Arora, MS; Sunil Garg, MS, DNB; Kiran Aggarwal, MD
From the Department Of Otorhinolaryngology and Head-Neck Surgery (Dr. Singh, Dr. Arora, and Dr. Garg) and the Department of Pathology (Dr. Aggarwal), Lady Hardinge Medical College and Associated Hospital, New Delhi, India.
(1.) Ying YL, Zimmer LA, Myers EN. Base of tongue schwannoma: A case report. Laryngoscope 2006;116(7):1284-7.
(2.) Cohen M, Wang MB. Schwannoma of the tongue: Two case reports and review of the literature. Eur Arch Otorhinolaryngol 2009;266(11):1823-9.
(3.) Sawhney R, Carron MA, Mathog RH. Tongue base schwanoma: Report, review, and unique surgical approach. Am J Otolaryngol 2008;29(2):119-22.
(4.) Pfeifle R, Baur DA, Paulino A, Helman J. Schwannoma of the tongue: Report of 2 cases. J Oral Maxillofac Surg 2001;59(7): 802-4.
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|Title Annotation:||HEAD AND NECK CLINIC|
|Author:||Singh, Gautam Bir; Arora, Rubeena; Garg, Sunil; Aggarwal, Kiran|
|Publication:||Ear, Nose and Throat Journal|
|Article Type:||Clinical report|
|Date:||Aug 1, 2015|
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