Intraosseous leptomeningeal cysts of the posterior cranial fossa.

Post-traumatic leptomeningeal cysts involving the occipital bone are intraosseous lesions which do not erode through the outer table, in contradistinction to leptomeningeal cysts elsewhere in the calvaria. In two of four reported cases, communicating hydrocephalus was associated with the intraosseous cyst. The clinical and radiological findings suggest that intraosseous leptomeningeal cyst of the posterior fossa represents a distinct entity. Resection of the cyst and closure of the dural defect may be less important than treatment of the communicating hydrocephalus.