Pineal Gland Cancer

The pineal gland is a small endocrine structure, measuring 10 to 14 mm in length, located in the midline of the brain at the superior aspect of the posterior margin of the third ventricle. On coronal imaging, the gland lies below the splenium of the corpus callosum and above and posterior to the tectum of the midbrain. The principal function of this gland is the secretion of melatonin, a hormone that regulates circadian rhythms. The gland receives environmental light-dark cycle information and provides feedback to the central nervous system, thereby contributing to the regulation of biological rhythms. The principal cells of the pineal gland are pinealocytes, which constitute the pineal parenchyma. Multiple pathologies are associated with this region due to the variety of cell types and structures adjacent to the pineal gland. Tumors of the pineal gland are classified into 3 subgroups—pineal parenchyma tumors, germ cell tumors, and lesions originating from adjacent structures. Other lesions encountered in this area include astrocytomas, oligodendrogliomas, pineal cysts, meningiomas, arachnoid cysts, ependymomas, chemodectomas, epidermoid cysts, dermoid cysts, metastasis, aneurysm of the vein of Galen, arteriovenous malformation, and cysticercosis. Important anatomical structures adjacent to the pineal gland include: Anteriorly: Third ventricle (pineal recess). Anterosuperiorly: Habenular nuclei. Superiorly: Internal cerebral veins, the vein of Galen (posteriorly), stria medullaris, splenium of the corpus callosum, and velum interpositum. Posteroinferiorly: Superior cerebellar cistern. Inferiorly: Superior colliculi of the midbrain. Anteroinferiorly: Posterior commissure. Differentiating tumors of the pineal region relies on integrating clinical presentation, imaging characteristics, tumor markers, and histopathology. Although many tumors present with overlapping symptoms such as hydrocephalus and Parinaud's syndrome, radiologic features, calcification patterns, and serum or cerebrospinal fluid (CSF) markers such as alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (β-hCG), help narrow the differential. Definitive diagnosis requires histological evaluation to guide management.