Ruptured spinal dermoid cyst with chemical arachnoiditis and disseminated intracranial lipid droplets.

A 33-year-old man presented with a 3-month history of gradually progressive leg weakness. Spinal MRI and myelography with CT demonstrated an extensive intradural abnormality suggesting a diffuse inflammatory or neoplastic process. Only after cranial CT and MRI demonstrated lipid droplets was the diagnosis of a ruptured spinal dermoid cyst suggested. Subsequent laminectomy revealed a ruptured intradural dermoid cyst in the lumbar spine, with chemical arachnoiditis.