Abstract: Objective To investigate the ultrastructural characteristics of hemangiopericytoma and angiomatous menigioma under the electron microscope. Methods Biopsy specimens of 6 cases with hemangiopericytoma and 6 cases with menigioma were analyzed with light and electron microscope combined with the clinical features. Results Intracranial hemangiopericytoma cells as spindle and polygonal cells are arranged characteristically in a palisade around a capillary. The cells are focally attached to one another and they are separated by basal lamina that is both discrete and diffuse. There were some dense bodies and pinocytotic vesicles around the tumor cell membrane. Angiomatous menigioma cells are distributed in the forms of whirlpool or bundle and have long interdigitating cellular processes, numerous cytoplasmic intermediate filaments and prominent desmosomes. Conclusion These observations confirm that the hamangiopericytoma is a malignant tumor and associated with intermediate mesoderm. While the meningioma may come from arachnoid epithelium which is a benign tumor. Each of the tumors had distinct source of histogenesis and the ultrastructural features have an essential Difference. Electron microscopy may help differential diagnosis between these two diseases.

Key words: intracranial hemangiopericytoma, angiomatous menigioma, ultrastructural differential diagnosis