[Biopsy in systemic vasculitis: guidelines and risks].

Biopsy examinations may be of great importance for the diagnosis of systemic vasculitides if they are correctly performed and some general pitfalls are avoided. Apart from technical mistakes (insufficient or too superficially excised material, necrotic tissue material without intact border areas, bad or retarded fixation), the following points should be kept in mind: Immunohistochemical and electron microscopic examinations are practically worthless for diagnostic reasons. The surgical access to the biopsy area and the tolerability of the intervention should be carefully evaluated. Biopsies without sufficient information to the pathologist about the clinical findings and the laboratory results are often responsible for insufficient pathology reports. Biopsies during or immediately after a corticosteroid treatment provide faulty results. Skin biopsies in systemic vasculitides usually present non-specific alterations. Polymyalgia does not cause a temporal arteritis and no conclusive findings within the striated musculature. A "blind" temporal artery biopsy has only a limited chance to provide findings of diagnostic value. The sites which offer the best possibilities for biopsy in various systemic vasculitides are enumerated and the possible histology findings at these sites are discussed.