MPO and microscopic polyangiitis: c-ANCA, generally corresponding to PR3-ANCA positivity, has the greatest sensitivity (64 percent) and specificity (95 percent) for GPA, while p-ANCA and MPO-ANCA positivity generally corresponds to other vasculitides, such as microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome) [7].