Anti-Myeloperoxidase P-ANCA is positive in which of the following ?

ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCA) ANCA are antibodies directed against ceain proteins in the cytoplasmic granules of neutrophils and monocytes. There are two major categories of ANCA based on different targets for the antibodies. The terminology of cytoplasmic ANCA (cANCA) refers to the diffuse, granular cytoplasmic staining pattern observed by immunofluorescence microscopy when serum antibodies bind to indicator neutrophils. Proteinase-3, a 29-kDa neutral serine proteinase present in neutrophil azurophilic granules, is the major cANCA antigen. More than 90% of patients with typical active granulomatosis with polyangiitis (Wegener's) have detectable antibodies to proteinase-3. The terminology of perinuclear ANCA (pANCA) refers to the more localized perinuclear or nuclear staining pattern of myeloperoxidase; other targets that can produce a pANCA pattern of staining include elastase, cathepsin G, lactoferrin, lysozyme, and bactericidal/permeability-increasing protein. Anti-myeloperoxidase antibodies have been repoed to occur in variable percentages of patients with microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis (Churg-Strauss), isolated necrotizing crescentic glomerulonephritis, and granulomatosis with polyangiitis (Wegener's). A pANCA pattern of staining that is not due to anti-myeloperoxidase antibodies has been associated with non-vasculitic entities such as rheumatic and non-rheumatic autoimmune diseases, inflammatory bowel disease, ceain drugs, and infections such as endocarditis and bacterial airway infections in patients with cystic fibrosis. Ref: Harrison&;s Principles of Internal Medicine; 20th edition; Chapter 385 The Vasculitis Syndromes; Page no: 2180