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Pineocytoma is a slow-growing tumor arising from the parenchyma of the pineal gland. These lesions correspond to WHO Grade II.
Pineocytoma accounts for less than 1% of all intracranial tumors, but about 45% of all pineal parenchymal tumors. These lesions usually arise in adults between the ages of 25-35. Both sexes are affected equally.
Pineocytoma arise from the parenchyma of the pineal gland.
Signs and symptoms are related to mass effect in the region of the pineal gland, e.g. hydrocephalus, neuro-ophthalmologic dysfunction, changes in mental status, brainstem dysfunction, hypothalamic dysfunction, or cerebellar findings.
MRI demonstrates a heterogeneously enhancing, often well-demarcated mass lesion in the region of the pineal gland.
Pineocytoma are well-circumscribed grey-tan lesions, firm in consistency. Necrosis and intra-tumoral hemorrhage are rare.
Pineocytoma is a well-differentiated neoplasm composed of small, uniform blue cells resembling pineocytes. Tumor cells form sheets separated by mesenchymal septa, as well as pineocytomatous rosettes, in which tumor nuclei line the periphery of a rosette filled with a lattice of delicate cytoplasmic processes. Homer-Wright and Flexner-Wintersteiner rosettes may be seen. Pineocytoma cells show strong immunoreactivity for synaptophysin and NSE.
The genetic basis of sporadic pineoblastoma has not been elucidated.
The 5-year survival rate is 86%. Seeding of the CSF is a poor prognosticator.