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Hypoglossal nerve schwannoma mimicking a carotid body paraganglioma in a patient with bilateral Eagle syndrome: A rare diagnostic challenge and review of the literature

Year: 2026

Type: article

Abstract: Background Extracranial hypoglossal schwannomas are exceptionally rare benign peripheral nerve sheath tumors and represent one of the least common non-vestibular cranial nerve schwannomas. Their clinical presentation is often nonspecific, while radiological findings may closely mimic other carotid space lesions, particularly carotid body paragangliomas, making preoperative diagnosis challenging. The coexistence of symptomatic Eagle syndrome may further obscure the clinical picture by producing overlapping cervicopharyngeal symptoms. Case Presentation We report the case of a 43-year-old woman presenting with a two-year history of bilateral odynophagia, referred otalgia, cervical pain, and pharyngeal discomfort predominantly affecting the left side and exacerbated by swallowing. Cervical computed tomography demonstrated bilateral elongated styloid processes consistent with Eagle syndrome according to the Langlais classification, together with an incidental hypervascular mass occupying the right carotid space. CT angiography revealed intense homogeneous arterial enhancement, widening of the carotid bifurcation, and superior extension toward the jugular foramen, findings highly suggestive of a carotid body paraganglioma. Plasma metanephrine and normetanephrine levels were within normal limits. Owing to financial constraints, magnetic resonance imaging was not performed. Surgical exploration unexpectedly demonstrated a well-encapsulated schwannoma arising from the hypoglossal nerve. Because of its intimate relationship with the nerve and superior extension toward the skull base, nerve-preserving subtotal microsurgical resection was deliberately performed to minimize postoperative neurological morbidity. Histopathological examination confirmed a benign schwannoma composed of Antoni A and Antoni B areas with Verocay bodies and diffuse immunoreactivity for S100 and SOX10. Adjuvant radiotherapy was administered for the residual tumor. At one-year follow-up, the patient remained neurologically intact, with preserved hypoglossal nerve function and stable residual disease on imaging. Conclusion This case highlights the diagnostic complexity of extracranial hypoglossal schwannomas, particularly when symptomatic Eagle syndrome coexists and CT angiography strongly suggests a carotid body paraganglioma. It also illustrates that preservation of neurological function should be a major consideration when complete tumor excision carries a high risk of hypoglossal nerve injury. In carefully selected patients, nerve-preserving subtotal resection combined with adjuvant radiotherapy may provide satisfactory local tumor control while maintaining excellent functional outcomes.

Source: Otolaryngology Case Reports

DOI: 10.1016/j.xocr.2026.100768