PubMedDate not supplied
Hemangiopericytomas (HP) have a characteristic vascular structure in histologic sections but this has not yet been visualized in three-dimensional form. Parts of typical vascular patterns were separated from paraffin blocks, re-embedded and cut in series. Three-dimensional images were created using the graphic reconstruction procedure of Staubesandt and Andres. The densely vascularized tumor tissue includes only very few arteries. Among these are some recurrent vessels and they abruptly divide into a large number of capillaries. Arterio-venous shunts could not be detected. Characteristic sinusoids, some of them like antlers in cross-section, change remarkably in calibre and have bizarre indentations and dilatations along their length. Their polymorphism includes an often collagenous wall, sometimes as spherical indentations. It seems that they are exclusively connected to the capillary network. The structure of the vessels can explain some angiographic characteristics such as diffuse accumulations of contrast media or their prolonged circulation time.