Fibrous Dysplasia Clivus

These images demonstrate a slightly expansile osseous lesion centered in the left aspect clivus with central lucency and peripheral ground glass appearance. The cortex is intact. These findings are characteristic of fibrous dysplasia. It can have a variable appearance which can look misleadingly aggressive on MRI. This is a congenital process where fibrous stroma replaces bone. It is predominantly found in younger patients and can result in deformity. Polyostotic fibrous dysplasia is a feature of McCune Albright syndrome. No treatment is necessary if the patient is asymptomatic.