Pulmonary Involvement in ANCA-associated Vasculitis Overlapping with Long-standing Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis are distinct autoimmune diseases, and their coexistence is rare, especially decades after the onset of SLE. A 74-year-old woman with long-standing SLE developed fever and bilateral centrilobular nodules with bronchial wall thickening on chest computed tomography (CT). She subsequently developed acute kidney injury and ANCA elevation with normal anti-dsDNA and complement levels, otitis media, and sinusitis. Lung histology revealed necrotizing granuloma with vasculitis. Granulomatosis with polyangiitis was diagnosed, and treatment with glucocorticoids and rituximab improved. ANCA should be tested in SLE patients with new pulmonary or extrapulmonary manifestations, particularly renal dysfunction.