A 34-year-old man presents with recurrent epistaxis, hemoptysis, and a 6-week history of migratory arthralgia. Chest CT shows multiple nodules with cavitation, and urine dipstick shows hematuria. Serology is most likely to show:

• A Cytoplasmic (c-ANCA) staining pattern with antibodies against proteinase 3 ✓
• B Perinuclear (p-ANCA) staining pattern with antibodies against myeloperoxidase
• C Linear IgG deposition along the glomerular basement membrane
• D Antibodies against the U1 ribonucleoprotein antigen

Explanation

Granulomatosis with polyangiitis is a small-vessel necrotizing vasculitis defined by c-ANCA, which gives a diffuse cytoplasmic immunofluorescence pattern and corresponds to antibodies against proteinase 3 in neutrophil azurophilic granules. Upper respiratory tract necrosis, cavitary lung nodules, and pauci-immune glomerulonephritis form the classic triad. Perinuclear p-ANCA with antimyeloperoxidase antibodies characterizes microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis, and linear GBM staining indicates anti-GBM disease instead.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.