Brain, Pineocytoma

Pineocytomas are rare, slow-growing tumours arising in the pineal gland parenchyma and are classified as WHO grade I. They are well-circumscribed and composed of small, uniform cells resembling normal pineocytes arranged in sheets or lobules. Pineocytomatous rosettes, formed by cell nuclei surrounding a nucleus-free centre composed of fine cytoplasmic processes, can be seen. Immunohistochemistry shows reactivity for synaptophysin, neuron-specific enolase, and neurofilament. Prognosis is excellent and patients are potentially cured with gross total resection.