Concurrent Anti-glomerular Basement Membrane (Anti-GBM) Disease and Immunoglobulin A Nephropathy (IgAN) Presenting With Severe Pulmonary-Renal Syndrome: A Case Report.

Anti-glomerular basement membrane (anti-GBM) disease is a rare, aggressive autoimmune condition that typically presents as rapidly progressive glomerulonephritis and can be complicated by pulmonary haemorrhage. The co-occurrence of anti-GBM disease and IgA nephropathy (IgAN) is extremely uncommon, though increasingly recognised as a distinct clinical and pathological entity. We describe a 51-year-old Sudanese man who presented with acute hypoxaemic respiratory failure, haemoptysis, severe anaemia, and acute kidney injury. Testing showed high levels of anti-GBM antibodies, with negative anti-neutrophil cytoplasmic antibodies. Chest imaging revealed diffuse alveolar haemorrhage. Renal biopsy demonstrated crescentic glomerulonephritis with linear IgG staining along the glomerular basement membrane, alongside mesangial deposits dominated by IgA, confirming the presence of both diseases. Treatment included plasma exchange, high-dose corticosteroids, cyclophosphamide, and bronchial artery embolisation, which led to significant respiratory improvement and stabilisation of kidney function. A review of published cases suggests that individuals with this overlap may experience better renal outcomes than those with anti-GBM disease alone, though serious pulmonary-renal symptoms can still occur. This case highlights the need for accurate clinicopathological assessment and prompt initiation of anti-GBM-specific treatment.