Diagnosis of pinealoblastomas by positive response to cobalt-therapy.

Surgical excision of pineoblastomas is considered dangerous, and relief of raised intracranial pressure by shunting followed by cobalt therapy is the preferred treatment. Demonstration by pneumoencephalography of tumour shrinkage after therapy confirms the diagnosis of pineoblastoma. Failure of the tumour to become smaller indicates a different pathology which calls for a surgical approach, except in the case of a brain stem tumour.