Abstract
ANCA-associated vasculitides (AAV) are a group of rare, autoinflammatory diseases with the presence of serum autoantibodies against neutrophil cytoplasm. Inflammation of the small vessels (polyangiitis) with granulomas and tissue necrosis represents the underlying mechanism of the disease.
Renal involvement is one of the most severe clinical manifestations of AAV and often presents with rapidly progressive glomerulonephritis (RPGN). We describe a case of a patient suffering from granulomatosis with polyangiitis with renal involvement, whose first renal biopsy was negative.
Despite that, the patient was intensely treated with glucocorticoids, cyclophosphamide, and azathioprine. Due to the progression of renal symptoms, a second biopsy was performed, and active glomerulonephritis was confirmed.
Based on the described case, we would like to highlight that despite the negative results of the first kidney biopsy, the patient suffered from a severe and progressive form of the disease with renal involvement that required rituximab treatment to reach remission.