Parapharyngeal Tumor

Abstract

Parapharyngeal tumors are rare and often missed because of their subtle presentation. This is true for a 21-year-old woman who presented with a gradually progressive swelling in her mouth for 3 months associated with difficulty in swallowing. On oral examination, there was a smooth bulge in the left pharyngeal wall pushing the left tonsil medially (Figure 1). Her systemic and neurologic examination results were within normal limits. Radiologic evaluation revealed an enhancing, smooth, well-defined encapsulated lesion in the left parapharyngeal space (Figure 2).Figure 2Magnetic resonance angiography images showing a well-enhancing mass in the parapharyngeal space displacing the internal and external carotid arteries: (1) right common carotid (1), right external carotid (2), left common carotid (3), left internal carotid (4), and left external carotid (5).View Large Image Figure ViewerDownload Hi-res image Download (PPT) A provisional diagnosis of schwannoma of the parapharyngeal space was made. Parapharyngeal space tumors are rare and account for only 0.5% of all head and neck tumors. Schwannoma is the most common neural tumor next to salivary gland tumors found in the parapharyngeal space. Vagus nerve is reported to be the origin for 50% of parapharyngeal schwannomas. Schwannomas are characterized by slow and asymptomatic growth; however, their progressive growth in the parapharyngeal region may result in pressure effect manifestations, such as dysphagia and hoarseness of voice. Treatment is surgical excision transorally or through a neck incision. Prognosis is good, and recurrences are rare after excision. In our patient, the lesion was excised through an external neck incision. The postoperative biopsy showed characteristic hypocellular (Antony B) and hypercellular (Antony A) areas that were immunohistochemicaly positive for S-100, consistent with schwannoma (Figure 3). The patient is asymptomatic at 9 months of follow-up visits.