Pediatric posterior fossa dermoid cyst: Diagnostic dilemma

Abstract

Dermoid cysts are rare congenital lesions of the brain. They are commonly located in the supratentorial region. Infratentorial dermoid cysts are uncommon. They can occupy cerebellopontine angle, midline posterior fossa, or brain stem. Midline post fossa dermoid cysts can be confused with another common lesion in this location. We describe a case of midline posterior fossa dermoid cyst in a 6-year-female child who presented with signs and symptoms of raised intracranial pressure. Magnetic resonance imaging showed posterior fossa lesion which was hypointense on T1-weighted images, hyperintense on T2-weighted images, and not enhancing on intravenous contrast administration. The lesion showed restricted diffusion on diffusion-weighted images. Radiological diagnosis was an epidermoid cyst. However, during surgery, we found hair follicles. Histopathological examination revealed dermoid cyst. The child recovered completely following cyst excision. We present a case of a posterior fossa dermoid cyst mimicking epidermoid cyst.