Congenital petrous cholesteatoma masquerading as facial nerve schwannoma: a case report with diagnostic and surgical insights

Introduction: Congenital petrous cholesteatoma is a rare skull base lesion with an insidious course and variable clinical presentation. Isolated facial nerve palsy without otologic symptoms is exceptional and may closely mimic a facial nerve schwannoma, leading to delayed or incorrect diagnosis. Case presentation: We report the case of a 25-year-old woman with no prior otologic history who presented with a 9-month history of progressive isolated right-sided peripheral facial nerve palsy, initially treated as idiopathic Bell’s palsy without improvement. Otoscopic and vestibular examinations were normal. High-resolution computed tomography and magnetic resonance imaging (MRI) revealed a right supralabyrinthine petrous lesion that radiologically mimicked a facial nerve schwannoma. Pure-tone audiometry demonstrated a mild preoperative right-sided conductive hearing loss (air–bone gap of 37 dB). Complete surgical excision was achieved via a middle cranial fossa approach, with preservation of cochlear and facial nerve integrity. Postoperatively, facial nerve function improved from House–Brackmann grade V to grade II within 3 days, with preservation of preoperative hearing levels and no postoperative deterioration. Discussion: This case illustrates the diagnostic challenge posed by congenital petrous cholesteatoma presenting as isolated facial nerve palsy, mimicking a facial nerve schwannoma. Diffusion-weighted MRI plays a pivotal role in differentiating cholesteatoma from other intrapetrous lesions. Careful surgical planning using a hearing-preserving approach allows complete excision while optimizing functional outcomes. Conclusion: Congenital petrous cholesteatoma should be considered in patients with atypical or treatment-refractory facial nerve palsy, even in the absence of otologic symptoms. Early radiological evaluation and tailored skull base surgery are essential for a favorable recovery.