Imaging description

The pineal gland develops as a diverticulum in the roof of the third ventricle between 4 and 8 weeks of gestational age. However, it is not redundant, like an appendix, and secretes melatonin, which controls diurnal rhythm [1]. Normally, it has a pinecone-like shape, measures about 8–10mm, and does not have a blood–brain barrier, enhancing normally on post-contrast imaging. Histologically, lobules of pineocytes, which are specialized neurons, and a small amount of astrocytes, along with fibrovascular stroma, make up the normal gland.

Mass lesions of the pineal region make up less than 1% of intracranial masses in adults. However, in the pediatric age group they account for about 3–8% of intracranial neoplasms [2]. Tumors of pineal parenchymal origin account for about 14–27% of pineal masses [3] and include low-grade pineocytoma (Fig. 30.1), intermediate-grade pineal parenchymal tumor of intermediate differentiation (PPTID) (Fig. 30.2), and highly malignant pineoblastoma (Fig. 30.3).

Pineocytomas are more commonly found in adults, with an excellent (85–100%) 5-year survival rate following gross total resection. PPTID is a WHO grade II/III neoplasm that exhibits slight female preponderance, makes up at least 20% of all the pineal parenchymal tumors, peaks in early adulthood, and has a 5-year survival of 40–74% [4].