Identification of a Hidden Lesion in Meckel's Cave: A Diagnostic Odyssey of Unilateral Facial Pain in a Nonagenarian.

Fibrous dysplasia of the temporal bone and petrous apex is an uncommon benign fibro-osseous disorder, particularly in elderly individuals. Involvement of the skull base may present with atypical cranial neuropathies and may mimic inflammatory, vascular, or neoplastic diseases. This report describes a 90-year-old woman with recurrent unilateral facial pain and episodic facial muscle contractions. Initial assessment considered neoplastic pathology and inflammatory vasculopathy. Serial clinical evaluations, laboratory investigations, and neuroimaging established the diagnosis of left petrous apex fibrous dysplasia extending into Meckel's cave and the internal auditory meatus, resulting in mass effect on the trigeminal nerve. Multidisciplinary neurosurgical and neurological consultation advised conservative management due to advanced age, stable symptoms, absence of progressive neurological deficits, and favourable response to pregabalin. This case highlights a rare and diagnostically challenging skull base lesion with overlapping features of trigeminal neuralgia and hemifacial spasm and underscores the importance of avoiding invasive interventions in carefully selected frail elderly patients when symptom control is achievable through conservative measures.