How would you approach a patient with incidentally noted infrarenal periaortitis with positive C-ANCA, normal inflammatory markers and no systemic symptoms?  

Based on data we and others have published over the past 20 years, the specificity of testing for ANCA depends on testing for antibodies to the specific antigens proteinase 3 (PR3) and myeloperoxidase (MPO) by ELISA or other newer methods. Immunofluorescence (IF) testing alone for ANCA is not accept...