Epidermoid tumour of the lateral ventricle.

Epidermoids occurring within the lateral ventricles are rare. At one time, they were regarded as anatomical curiosities. The lesions are of developmental aetiology, due to migration of epiblast inclusion at the time of formation of the cerebral vesicle. They are slow growing, and presentation is non-specific in the form of deteriorating mental functions. Generally seen in the fifth decade, but they have also been observed in the paediatric age group. MRI is suggestive of a cystic lesion, and is confirmed to be a typical epidermoid within the lateral ventricle at operation, often having a connection to the midline through the choroidal fissure. The cysts should be excised with no additional morbidity. Histopathology reveals typical stratified squamous epithelium.