The purpose of this study is to collect existing tissue specimens from subjects enrolled in Vasculitis Clinical Research Consortium (VCRC) studies. Analysis of these tissue specimens and linked clinical data collected through VCRC studies may lead to the identification and development of a series of translational research projects. Results of these studies will provide vasculitis researchers with insight into the causes of these diseases and generate new ideas for diagnostic tests and therapies, and will be of great interest to the larger communities of researchers investigating vasculitis and other autoimmune, inflammatory, and vascular diseases.