The 2022 ACR/EULAR classification criteria for ANCA-associated vasculitis distinguish GPA (granulomatosis with polyangiitis) from MPA (microscopic polyangiitis) primarily using which antibody:

• A Anti-GBM for GPA; PR3-ANCA for MPA
• B ANA for GPA; ANCA for MPA
• C Anti-dsDNA for GPA; complement C3/C4 for MPA
• D PR3-ANCA (c-ANCA) for GPA; MPO-ANCA (p-ANCA) for MPA ✓

Explanation

GPA is strongly associated with PR3-ANCA (proteinase 3 ANCA, c-ANCA pattern on IF) while MPA is predominantly associated with MPO-ANCA (myeloperoxidase ANCA, p-ANCA pattern). The 2022 ACR/EULAR classification criteria assign positive points for PR3-ANCA in GPA and negative points (favouring MPA) in a scoring system that also includes granulomatous features, upper respiratory involvement, and absence of certain histologic findings. Eosinophilic GPA (EGPA) is commonly MPO-ANCA positive.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.