Epidermoid, Intraventricular
- Epidermoids represent 0.2-1% of all intracranial masses. They arise from inclusion of epithelial remnants trapped during 3-5 weeks of fetal life (remember that choroid plexus are also formed from invagination of ectodermal tissues).
- Intraventricular epidermoids are more in 4th ventricle followed by lateral ventricles.
- More common in middle age; very rare in children
- If ruptured, aseptic meningitis occurs.
- Long T1 and T2 are due to keratin in solid crystalline state. Epidermoids have restricted ADC and complex FLAIR signal, unlike arachnoid cysts.
