A case of malignant hemangiopericytoma: an immunohistochemical and ultrastructural study.

We report one case of malignant hemangiopericytoma which started with a tumor in the lower jaw and multiple nodules in the lung. The tumor quickly metastasized to the brain and chemotherapy was not at all effective. Hemangiopericytoma is generally diagnosed by its histological characteristics. Recently, however, electron microscopy and immunohistochemical methods have been used for its diagnosis. In our case, electron micrograph showed the growth of hemangiopericytoma cells around immature endothelial cells. In addition, the tumor cells reacted positively only with anti-vimentin antibodies, and the endothelial cells in the tumor tissue were positive for antifactor VIII antibodies. The observed features were consistent with the characteristics of hemangiopericytoma.