A Rare Radiologic Cause of Peripheral Facial Paralysis in a Child: Temporal Bone Fibrous Dysplasia

Mohamed Vall Yehdih; Ghizlane Zouhir; Daoud Bentaleb; Dalal Laoudiyi; Kamilia Chbani; Salam Siham

doi:10.5455/ajdi.20260217113558

Abstract
Peripheral facial paralysis (PFP) is relatively frequent in the pediatric population, with idiopathic causes being the most common. Cross-sectional imaging, particularly computed tomography (CT) and magnetic resonance imaging (MRI), plays a pivotal role in identifying rare secondary etiologies, including osseous lesions of the temporal bone.We report the case of a 5-year-old boy presenting with progressive left-sided peripheral facial paralysis evolving over three years, without any history of trauma, infection, or associated neurological symptoms. Clinical examination revealed a House–Brackmann grade V facial palsy. MRI demonstrated non-specific opacification of the left mastoid air cells without intracranial extension. High-resolution non-contrast CT of the temporal bone revealed an expansile, sclerotic lesion with a characteristic ground-glass appearance involving the tympanic and mastoid segments of the facial nerve canal, responsible for canal narrowing. These imaging findings were highly suggestive of fibrous dysplasia of the temporal bone. Histopathological examination following surgical biopsy confirmed the diagnosis.

Key words: Peripheral facial paralysis; Fibrous dysplasia; Temporal bone; Facial nerve canal; Pediatric imaging