Histopathology of the Pineal Region Tumors

From a histopathological point of view, as well as from the point of view of the molecular markers and of the genetic expression profile, the tumors of the pineal region are heterogeneous pathological entities. Their diagnosis poses a challenge to the pathologist, as these are rare tumoral processes. In this chapter, we present the tumor entities of the pineal gland (pineocytoma, pineal parenchymal tumor of intermediate differentiation, pinealoblastoma (PB), and papillary tumor of the pineal region), reviewing aspects related to their origin, as well as to their macroscopic and histopathological aspects. In line with the latest world health organization (WHO) classification of brain tumors, we have focused on the molecular tests (immunohistochemistry and genetics) necessary to establish the diagnosis.