Alveolar haemorrhage–dominant presentation of anti-GBM disease triggered by hydrocarbon exposure in a patient with a congenital solitary kidney: a case report

Anti-glomerular basement membrane (anti-GBM) disease is a rare small-vessel vasculitis typically presenting with rapidly progressive glomerulonephritis and/or pulmonary haemorrhage. Environmental and occupational exposures, particularly inhaled hydrocarbons, are recognised triggers, however, cases with initially isolated pulmonary involvement remain diagnostically challenging. We report a 32-year-old man with a congenital solitary kidney and no prior renal disease who presented with a three-week history of exertional dyspnoea, dry cough and intermittent haemoptysis. He had daily occupational exposure to petroleum-based solvents for five months without respiratory protection. Initial evaluation revealed bilateral alveolar infiltrates on chest X-ray and diffuse ground-glass opacities consistent with alveolar haemorrhage on high-resolution computed tomography. Laboratory tests showed severe hypochromic microcytic anaemia, markedly elevated inflammatory markers, and acute kidney injury, with urinalysis demonstrating proteinuria, haematuria and casts. Anti-GBM antibodies were strongly positive, while antineutrophil cytoplasmic antibodies were negative. Because of ongoing alveolar haemorrhage and the presence of a single functioning kidney, renal biopsy was deferred and urgent treatment initiated with pulse methylprednisolone, intravenous cyclophosphamide and high-dose oral prednisone. Pulmonary symptoms and inflammatory markers improved rapidly; however, renal function continued to deteriorate and the patient subsequently required chronic haemodialysis. This case illustrates an unusual presentation of anti-GBM disease with initially isolated pulmonary manifestations in the context of substantial occupational hydrocarbon exposure and a congenital solitary kidney. It underscores the importance of maintaining a high index of suspicion for anti-GBM disease in patients with unexplained alveolar haemorrhage and relevant environmental exposures, and highlights the need for prompt immunosuppressive therapy even when histological confirmation is not immediately feasible.