ABSTRACT
The pineal gland, a mid-line brain structure located within the anterior quadrigeminal cistern at the level of the thalamus, lies on top of the superior colliculi of the mesencephalon at the posterior recessus of the third ventricle between the posterior and the habenular commissures. During the second month of gestation, it appears as an evagination of undifferentiated, round, nucleated cells with a scanty cytoplasm, then undergoes extensive cellular differentiation, resulting in the appearance of the adult gland by the end of the first year of life. Pineal region tumors are rare, comprising about 1 percent of primary central nervous system (CNS) tumors in the adult and 3-8 percent of pediatric brain tumors (Mena et al., 2000). They are tumors of diverse histopathology. The variety of neoplasms that can be encountered in the region of the pineal gland reflects the diversity of cell types in this organ. In this section, we will consider pineal parenchymal tumors (PPT), derived from the specialized neurosecretory elements of the mature gland, and gliomas, which presumably arise from resident pineal glial cells or from other glial cells in the vicinity of the pineal gland. In addition, benign pineal cysts, often asymptomatic, can be found and must be differentiated from pineal tumors.
