Anti-GBM/ANCA double-positive crescentic nephritis in an elderly patient presenting with heart failure-like symptoms: A case report

Rationale

Anti-glomerular basement membrane (anti-GBM) antibody disease and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis represent the 2 leading causes of rapidly progressive glomerulonephritis (RPGN). The coexistence of these conditions is rare, typically progresses rapidly, and has a poor prognosis. Elderly patients often present with nonspecific systemic symptoms, increasing the likelihood of misdiagnosis and treatment delay. Patient concerns: A 74-year-old woman presented with a one-month history of intermittent shortness of breath, worsening progressively over ten days, accompanied by nausea and vomiting. She denied hemoptysis, gross hematuria, rash, or arthralgia. Diagnoses: Initial assessment suggested heart failure. However, laboratory results revealed severe renal impairment (creatinine: 1025.99 μmol/L). Renal biopsy demonstrated crescent formation in over 80% of glomeruli, with immunofluorescence showing linear immunoglobulin G deposits along glomerular capillary loops. Serological testing revealed markedly elevated anti-GBM antibody (>400 RU/mL) and MPO-ANCA (108.4 RU/mL) levels, together with a perinuclear ANCA (P-ANCA) pattern on indirect immunofluorescence, supporting the diagnosis of anti-GBM glomerulonephritis with concomitant MPO-ANCA positivity.