Uncommon Presentation of Pauci-Immune Crescentic Glomerulonephritis in a Young Adult with Normal Kidney Function

Introduction: Crescentic glomerulonephritis is common in pauci-immune reno-pulmonary disorders, typically presenting with acute kidney injury (AKI) and diffuse alveolar hemorrhage (DAH). We present a case of pauci-immune crescentic glomerulonephritis (PICGN) with migratory polyarthralgia, DAH and remarkably preserved kidney function . Case Description: 19 year old male presented with seborrheic dermatitis and polyarthralgia with associated recurrent "sinus infections." Workup revealed microscopic hematuria, nephrotic range proteinuria (>5g/24 h), serum creatinine (0.8-1 mg/dl), and positive serology for proteinase-3 (PR3) and c-ANCA. Later developed hemoptysis with bronchoscopy notable for diffuse alveolar hemorrhage. Renal biopsy showed fibro-cellular crescents in 34/45 glomeruli consistent with pauci-immune crescentic GN. Treated with cyclophosphamide and methylprednisone along with plasma exchange with subsequent improvement in symptoms and proteinuria. Discussion: PICGN is typically associated with rapid eGFR loss correlated with extent of crecent formation. Despite renal biopsy Figure 1 revealing extensive crescents GFR was preserved. Main prognostic factor in PICGN is clinical vigilance and maintaining low threshold for aggressive treatment. Literature review suggests renal biopsy if clinical concern for ANCA vasculitis regardless of presenting renal function. Our case highlights the clininical importance of renal biopsy in long term prognostication and significant pathologic findings despite preservation of GFR. In a cohort of 70 biopsy proven PICGN patients, mean serum creatinine at presentation was 5.5 ± 2.1 mg/dl and mean proteinuria of 2.5 g/24 h. This signifies the importance of clinical diagnosis and management in atypical presentation of cases. The successful management of this case, involving the identification and subsequent initiation of cyclophosphamide, pulse dose steroids, and plasma exchange, highlights the importance of early and aggressive treatment to prevent progression and preserve renal function.Fig. 1