Other Astrocytic Tumors

Rare, accounting for less than 1% of all CNS neoplasms

Typically seen in children and teenagers, with over two thirds of tumors occurring in patients 18 years of age and younger

No gender predilection

Tumor normally found in superficial cortex and often involves the meninges

Strong preference for the temporal lobes

Prolonged history of seizures is the most common presenting symptom

Favorable prognosis, with 5- and 10-year survival rates of 80% and 70%, respectively

Surgical excision alone is often curative

Adjuvant therapy indicated in cases of incomplete resection, recurrence, or tumors with anaplastic features

15% to 20% of tumors undergo malignant degeneration

Typically seen on MRI and CT as cystic mass with enhancing mural nodule, but may also be a solid mass

Seen in cerebral cortex, often extending to and involving the overlying meninges

Solid or cystic mass that is well demarcated and firm

Calcifications are often identified

Composed of cells with significant nuclear and cellular pleomorphism

Composed predominantly of spindled cells with astrocytic features

May have storiform or fascicular growth pattern

Multinucleated cells are often prominent

“Lipidized” tumor cells have foamy, lipid-laden cytoplasm and are seen in approximately 25% of cases

Mitotic rate is typically very low, but no microvascular proliferation or necrosis

Eosinophilic granular bodies (EGB) and perivascular lymphocytes are often present

Increased mitotic rate (>5 mitoses per 10 high-power fields) and necrosis are suggestive of anaplastic PXA

Tumor cells are strongly immunoreactive for GFAP and S-100

Neuronal markers (synaptophysin, neurofilament) are reactive in about 25% of cases

Ki-67 proliferation index is usually less than 3%

EGBs are PAS positive

Reticulin deposition surrounds small groups of tumor cells

BRAF gene (7q34) point mutation (V600E) in two thirds of cases

50% of lesions will have loss of chromosome 9

Multiple other genetic alterations can be found but are not specific to PXAs