Abstract
Forty-nine cases of intracranial vascular tumors including 19 hemangioblastomas, 12 angiomatous meningiomas, 6 hemangioblastic meningiomas, and 12 meningeal hemangiopericytomas were studied by immunohistochemistry and electron microscopy. In all cases of hemangioblastoma, tumors were located in the cerebellum. In contrast, the other vascular tumors originated above the tentorium. The endothelial cells, pericytes and stromal cells were principal elements of the hemangioblastoma. These elements consisted an organoid structure in the tumors. The stromal cells were classified into foamy, vacuolated, and epithelioid types based on the histological appearance of the cytoplasm, but these types did not correlate with the age of patients. Angiomatous meningiomas were merely highly vascular meningioma and characterized by a fibrous hyaline thickening of vessel walls and microcystic changes of the stroma. In terms of microcystic degeneration, these organic changes of the vascular channels seemed to be responsible for the accumulation of extracellular fluid in the stroma. It is suggested that the angiomatous meningioma and the microcystic meningioma are closely related neoplasms. Each case seemed to make a spectrum between these tumor entities. Tumor cells of hemangioblastic meningiomas showed several immunohistochemical and electron microscopic features common to most meningiomas. The hemangioblastic meningioma, be definitely separated from capillary hemangioblastoma of the cerebellum, might be included in the spectrum between angioblastic meningioma and microcystic meningioma. Meningeal hemangiopericytoma was a highly cellular neoplasm with several anaplastic features. There was no morphological evidence of endothelial, pericytic, or arachnoidal differentiations in the tumor. It is suggested that the hemangiopericytoma is a poorly differentiated neoplasm originated from perivascular mesenchymal cells. This study also demonstrated the LN-5 antigen to be a useful immunohistochemical marker of the endothelial cells.
