Answer: Meningioma

Histology: The dura-based-mass is composed of uniform cells with bland nuclei and finely vacuolated cytoplasm. Neither whorls nor psammoma bodies are present
No mitoses were found.

Discussion: Hemangioblastomas, while often included in the differential diagnosis of “odd”, low grade, supratentorial, dura-based lesions, they are actually quite rare in this locale. Histologically, hemangioblastomas are more vascular and lobular than the present lesion, and contain scattered “interstitial cells” with large dark pleomorphic nuclei. The latter are not present here. At least some of the cytoplasmic vacuoles of hemangioblastoma are generally larger than those in the present case, and reticulin is abundant. The lesion lacks the high cellularity and “staghorn” vessels of hemangiopericytoma. The tumor is considerably less epithelioid than the typical clear cell carcinoma. Mitoses are absent. Immunohistochemically, meningiomas are EMA-positive, as was this case. Recent studies suggest that immunohistochemistry for inhibin can be used in identifying hemangioblastoma with its positive interstitial cells. Staining may be focal and weak, however.