Clival Epidermoid-MRI

38 yr old male with headache has a restricted diffusion, expansile , possibly extraaxial lesion within clivus in basisphenoid and basiocciput region, showing pressure erosions and scalloping with cavernous ICAs compression, no bleed or MR demonstrable calcification-possibly epidermoid.

Teaching points by Dr MGK Murthy, Abdul Hamid and Venkat

• Usually less than1%of intracranial tumours. Common in posterior fossa at CP angles and usually large and intradural, Extradural less common. Non restricted diffusion varieties not known
• Differentials include arachnoid cyst(not restricted on DW, cholesteatoma (petrous apex may be involved), cysts of of various varieties including infectious type etc
• Have outer capsule comprised of connective tissue, which surrounds a layer of keratinized stratified squamous epithelium
• Classically benign and slow growing , though occasional malignant transformation at CP angles described
• Removal of capsule to perform complete excision difficult in about 20 to 50% cases due to adhesions to nerves, pia & vessels.