Patient presenting with cutaneous vasculitis, glomerulonephritis, peripheral neuropathy, which investigation is to be performed next that will help you diagnose the condition?

Ans. a. ANCAANTINEUTROPHIL CYTOPLASMIC ANTIBODIESAntineutrophil cytoplasmic antibodies (ANCAs) are antibodies directed against certain proteins in the cytoplasm of neutrophils.The cytoplasmic (c) ANCA refers to the diffuse staining pattern observed when serum antibodies bind to indicator neutrophils; it is seen in>90% of patients with Wegener granulomatosis.Perinuclear (p) ANCA refers to a localized staining pattern observed on the indicator neutrophils, the major target of these antibodies being the enzyme myeloperoxidase; it is found in PAN and Churg-Strauss but is a nonspecific test.