PINEOBLASTOMA

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PINEOBLASTOMA
Spineoblastoma.jpg
Sagittal MRI showing pineoblastoma
Tumor Class PNET
Cell of origin neuronal precursor
WHO Grade IV
Survival 24 months
Treatment Surgery, Radiation
Histologic Features
Radiographic Features

Contents

Definition

Pineoblastoma is highly malignant, primitive embryonal tumor of the pineal gland. These lesions correspond to WHO Grade IV.

Epidemiology

Pineoblastoma accounts for about 4% of all pineal parenchymal tumors. These lesions usually arise in the first two decades of life. There is a slight male predominance.

Localization

Pineoblastomas arise from the parenchyma of the pineal gland.

Clinical presentation

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.

Imaging

MRI demonstrates a heterogeneously enhancing, large and often lobulated mass lesion in the region of the pineal gland.

Axial T1 weighted MRI with contrast showing pineoblastoma

Macroscopy

Pineoblastomas are soft and friable tumors. Infiltration of the surrounding structures is frequent, and these lesions are poorly demarcated from the surrounding brain. Calcifications are rare. Necrosis and intra-tumoral hemorrhage may be present.

Histopathology

Pineoblastomas are composed of patternless sheets of densely packed small blue cells with round-to-irregular nuclei and scant cytoplasm. Homer-Wright and Flexner-Wintersteiner rosettes may be seen. The high cellularity, presence of multiple mitoses, and lack of pineocytomatous rosettes differentiate pineoblastoma from pineocytoma.

Molecular genetics

Pineoblastoma may occur in patients with bilateral retinoblastoma (“trilateral retinoblastoma syndrome.”). The genetic basis of sporadic pineoblastoma has not been elucidated.

Prognosis

Seeding of the CSF is common, and extracranial metastasis may occur. Projected 1-, 3- and 5-year survival of patients with pineoblastoma who have received aggressive multi-modality therapy are 88%, 78% and 58%, respectively. Mean survival time following surgical intervention is 25.7 months.

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