Case Report
An 11-year-old female presented with an asymptomatic, right neck mass first noted 7 months prior. Physical examination was notable for a large right parapharyngeal space mass on palpation of the oropharynx and neck, with medialization of the right oropharynx. Atrophy and fasciculations of the right side of the tongue were seen, consistent with a right hypoglossal nerve paralysis. Flexible fiberoptic laryngoscopy demonstrated effacement of the right nasopharynx and oropharynx, with preserved vocal fold function. All other cranial nerves were intact.
Magnetic resonance imaging (MRI) of the neck highlighted a large ovoid mass in the right parapharyngeal space measuring 4.9cm x 3.7cm x 7.4cm. The tumor extended from the jugular foramen superiorly to the level of C5 inferiorly, but without intracranial extension. The mass caused acute displacement of the internal and external carotid arteries anteriorly, and compression of the internal jugular vein postero-laterally. T2-weighted MRI sequences demonstrated heterogeneous hyperintensity (Figures 1A and 1B). T1-weighted MRI sequences showed a hypointense lesion with homogeneous avid enhancement after administration of gadolinium-based contrast, consistent with schwannoma (Figure 1C).1 Genetic testing and Pediatric Brain and Nervous System Tumor Panel (Invitae; San Francisco, California) were negative for any germline mutations. Following multi-disciplinary review and extensive patient and family discussion, the decision was made to proceed with complete surgical excision, involving a combined transcervical-mandibulotomy approach (Figures 2A-2E).
Histopathologic examination of the tumor confirmed schwannoma with immunohistochemistry showing diffuse S100 and focal SMA positivity. Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), a next-generation sequencing assay of all protein-coding exons of 468 cancer genes, demonstrated TET1deletion of exons 1 and 2.
The patient underwent an uncomplicated post-operative recovery. A temporary gastrostomy tube was sited to assist with nutritional supplementation during swallow rehabilitation. A right vocal fold injection augmentation with Prolaryn Plus (Merz Pharma GmbH & Co. KGaA; Frankfurt, Germany) was performed with a good voice result. At 3 months post-operation, the patient had no significant dysphagia or aspiration and demonstrated a normal voice.