Angioarchitecture and CD133 + tumor stem cell distribution in intracranial hemangiopericytoma: A comparative study with meningioma

Angioarchitecture plays an important role in the malignant development of intracranial hemangiopericytoma. It remains poorly understood whether high frequency of hemorrhage during clinical surgery for intracranial hemangiopericytoma is associated with angioarchitecture. The present study utilized hematoxylin-eosin staining, and immunohistochemical staining with epithelial membrane antigen, vimentin, CD34, von Willebrand factor (vWF) and CD133 to observe characteristics of angioarchitecture. In addition, silver stains were used to demonstrate changes in reticular fibers in the wall of vessel channels in intracranial hemangiopericytoma and meningioma. Five patterns of angioarchitecture were identified in intracranial hemangiopericytoma, namely tumor cell islands, vasculogenic mimicry, mosaic blood vessels, sprouting angiogenesis, and intussusceptive angiogenesis. Several CD133 + tumor cells were found to form tumor cell islands. A connection between vWF + and vWF - channels was detected in the pattern of intussusceptive angiogenesis, and some vimentin + tumor cells were embedded in the periodic acid-Schiff positive channel wall. Incomplete threads of reticular fibers formed the walls of larger pseudo-vascular channels and some tumor clumps or scattered tumor cells were detected "floating" in them. The angioarchitecture, specific markers and reticular fibers of intracranial hemangiopericytoma were significantly different from meningioma. Angioarchitecture provides a functional vascular network for vascular evolution in intracranial hemangiopericytoma and contributes to significant intra-operative bleeding.