Pineoblastoma

General characteristics

Pineoblastoma (WHO grade IV) is a highly malignant primitive embryonal tumor of the pineal gland that manifests primarily in children (Mena et al. 2000b).

Epidemiology

Pineoblastomas are rare brain tumors that make up approximately 45% of all pineal parenchymal tumors.

Imaging

This tumor appears histopathologically similar to medulloblastoma, with focal areas of hemorrhage and necrosis. It tends to metastasize through the subarachnoid pathways into the meninges and subependymal space. The diagnosis of the exact histopathological type of pineal tumor is not possible in most cases; however, the main clinical question is the differentiation from cystic lesion in the pineal region. Mass lesions are normally solid with a marked tumor enhancement.

The signal is isointense to gray matter on T2-weighted imaging and hypointense on the T1. Pineocytomas, with a high amount of cytoplasm are generally more intense on T2. Calcification may occur but the amount is normally too small to allow signal changes in MRI.