Clinicoradiological Dissociation in a Giant Lytic Posterior Fossa Epidermoid Cyst: A Case Report.

Intracranial epidermoid cysts (ECs) are rare benign congenital lesions characterized by slow growth and late clinical presentation. Giant ECs of the posterior fossa are exceptionally uncommon and typically associated with early neurological deterioration due to the confined anatomy in this region. We report the case of a 74-year-old woman presenting with chronic headache and mild vertigo, with no focal motor or cranial nerve deficits. MRI revealed a giant extra-axial EC of the left posterior fossa with occipital bone lysis on CT scan. Despite the radiological findings, no acute hydrocephalus or intracranial hypertension was present. The patient underwent surgical resection. Histopathological examination confirmed the diagnosis of an EC. This case highlights the striking clinicoradiological dissociation that may be observed in giant posterior fossa ECs.