Cerebellar hemangioblastoma with prominent stromal astrocytosis: diagnostic and histogenetic considerations.

A cerebellar hemangioblastoma with atypical radiologic and morphologic features is reported. On computed tomography this tumor presented as a single ring-enhancing mass in the right cerebellar hemisphere without adjacent cyst formation. It was radiologically indistinguishable from an abscess or malignant neoplasm. Postmortem examination demonstrated a circumscribed, cystic neoplasm arising in the pia at the base of a sulcus. Microscopically, the tumor contained a prominent astrocytic component that mimicked the appearance of a highly vascular astrocytoma. Hemangioblastomas with this degree of astrocytosis are unusual. They must be distinguished pathologically from both cystic astrocytoma and mixed hemangioblastoma-glioma (angioglioma).