[Molecular diagnosis of collagen vascular diseases and vasculitides].

Collagen vascular diseases and vasculitides comprise various diseases, which may affect virtually every organ system. Therefore, their diagnosis and management is often an interdisciplinary challenge. Because of the heterogeneous symptoms, these diseases have significant overlap, which interferes with the clinical diagnosis and may require additional investigation. Therefore, a rational and comprehensive diagnostic work-up should be performed at the initial presentation before initiation of therapy. The detection of antinuclear (ANA) or anticell antibodies by indirect immunofluorescence microscopy on Hep2 cells is used to screen for autoantibodies in collagen vascular diseases. The molecular specificity of autoantibodies should be further characterized using immunoassays with recombinant or purified protein. When systemic autoimmune disease is suspected, the function of the frequently affected organs should be evaluated. The immunopathological findings should always be interpreted in the context of clinical, histological, and imaging data. The detection of autoantibodies is helpful for the initial diagnosis, provides prognostic information, may indicate involvement of organs or systems and some parameters may also be used for disease monitoring. The clinical significance of autoantibodies is emphasized by the fact that their detection constitutes diagnostic criteria for most collagen vascular diseases and several vasculitides. The screening for ANCA may be performed using immunoassays with recombinant myeloperoxidase and proteinase 3 or by indirect immunofluorescence microscopy on granulocytes. In this article, the current diagnostic tools and their relevance for the diagnosis and monitoring of systemic autoimmune diseases with primary skin involvement are reviewed.