Facial Nerve Schwannoma Mimicking Post-Traumatic Middle-Ear Disease: A Diagnostic Pitfall

Facial nerve schwannoma may present with otological symptoms despite preserved facial nerve function, creating a diagnostic challenge when the lesion involves the middle ear. A 75-year-old man developed aural fullness and hearing loss following craniofacial trauma. Otoscopy revealed a dark reddish retrotympanic mass. Computed tomography demonstrated soft-tissue opacification of the middle ear and mastoid with a tegmen tympani defect, raising suspicion of post-traumatic middle-ear disease with cerebrospinal fluid leakage. Facial function remained normal. Surgical exploration confirmed a dural defect and cerebrospinal fluid leakage but unexpectedly revealed an extensive tumour involving the facial nerve. We performed complete excision, followed by facial nerve reconstruction using a great auricular nerve interposition graft. Histopathological examination confirmed schwannoma. Retrospective review of the pre-operative computed tomography images demonstrated smooth facial-canal expansion and enlargement of the stylomastoid foramen that had been present but not specifically sought or recognised before surgery. This case highlights how coexisting traumatic abnormalities may obscure an underlying facial nerve schwannoma. Careful assessment of the entire facial nerve pathway on temporal bone imaging may provide an important diagnostic clue in patients with an unexplained retrotympanic mass, even when facial function is preserved.