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The diagnosis of systemic vasculitis (SV) is a major clinical challenge due to the very different forms of presentation and requires an interdisciplinary approach. Targeted laboratory diagnostics support making the diagnosis, differential diagnosis and classification and are also a key component in the detection of active organ manifestations and treatment complications. The basic laboratory tests include the erythrocyte sedimentation rate (ESR), C‑reactive protein (CRP), blood count, serum creatinine, urinalysis, specific autoantibodies, complement, immunoglobulins, cryoglobulins and hepatitis B and C serology. Antineutrophil cytoplasmic autoantibodies (ANCA), antiglomerular basement membrane antibodies (anti-GBM antibodies) and anti-C1q antibodies are valuable laboratory markers for the diagnosis of the various forms of small vessel vasculitis. There are no specific laboratory tests for the diagnosis of medium and large vessel vasculitis. Despite advances in our understanding of the pathogenesis of vasculitis, no biomarkers have yet been identified that can be reliably used to guide treatment or that are useful in distinguishing vasculitis from other inflammatory diseases such as infections or treatment complications., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Cryoglobulinemic vasculitis is a disease of the small arteries and affects the skin, joints, peripheral nerves, kidneys and other organs. Even small amounts of cryoglobulins can lead to severe impairment for the patient but the detection of such low amounts of cryoglobulins can be difficult. The causes of cryoglobulinemic vasculitis include monoclonal hematological diseases, autoimmune diseases and chronic infections. Therapy involves treatment of the underlying disease and glucocorticoids, rituximab and plasmapheresis depending on the severity of the vasculitis. Recognition of typical clinical symptoms is essential in order to initiate appropriate laboratory diagnostic procedures. Sometimes many investigations are necessary. In the absence of clinical trials treatment recommendations can often only be derived from registry data.

Inflammation plays a pivotal role in atherosclerosis and coronary heart disease. Inflammatory processes of the coronary arterial wall are involved in plaque formation, progression and, finally, plaque instability consecutively leading to the clinical manifestations of stable coronary artery disease or acute coronary syndromes (unstable angina, non-ST elevation and ST elevation myocardial infarction). Acute coronary syndromes result from plaque rupture or erosion leading to local thrombus formation with consecutive necrosis of myocytes due to ischemia, which is associated with widespread and diffuse pancoronary and panmyocardial inflammation. Accordingly, markers of myocardial necrosis (e. g., cardiac troponins) do have crucial diagnostic and prognostic value. In case of troponin-negative acute coronary syndromes, however, markers of inflammation emerged as potentially useful tools for risk stratification. C-reactive protein has been shown to serve as a powerful predictor of future cardiovascular events following acute coronary syndromes, even if troponins are not (yet) positive. Moreover, a variety of pro- (soluble CD40 ligand, placental growth factor, interleukin-6, pregnancy-associated plasma protein A, myeloperoxidase, monocyte chemoattractant protein-1) and anti-inflammatory markers (interleukin-10, activin A) have been suggested to provide relevant prognostic information in patients with acute coronary syndrome. However, the clinical utility of these novel markers has not been established so far.

A 45-year-old male patient presented with cold-induced generalized livedo reticularis, repeated acral ulcerations and purpura, Raynaud's phenomenon, and peripheral polyneuropathy. The patient also experienced malaise, vertigo, and transient amaurosis whenever he was exposed to low temperatures. Skin biopsies of the livedo reticularis revealed marked dilatation of the small dermal blood vessels and circumscribed leukocytoclastic vasculitis. Essential cryofibrinogenaemia was diagnosed on the basis of detection of this cryoprotein in the chilled blood plasma with increased viscosity. Pulsed therapy with dexamethasone and cyclophosphamide resulted in marked relief of the symptoms, and cryofibrinogen was no longer detectable in the patient's plasma.

Antibodies against cytoplasmic structures of neutrophilic granulocytes and monocytes (ACPA) are highly specific for Wegener's granulomatosis (WG). We found 77 out of 105 patients suffering from clinically and histologically proven WG seropositive for ACPA, whereas only 8 patients out of 123 other vasculitides showed ACPA, too. Of those were 3 cases out of 20 with panarteritis nodosa and 5 patients out of 51 with unclassified systemic vasculitides. About half of the patients showed systemic inflammatory activity with respect to C-reactive protein values above 10 mg/l at time of serum sampling.