Small vessel vasculitis

Requirements for diagnosis include full disclosure of the past and present medical history with review of laboratory results, especially diagnostic immunology. Histology should be of targeted biopsies of recent active lesions in preference to blind biopsies. Sampling should be extensive using high-quality thin sections. Systematic microscopic evaluation of architectural features and cellular detail is necessary. Tissue immunofluorescence is a useful adjunct. The final opinion must take all available information into account but may ultimately depend on a critical judgement by the pathologist.