RESUMEN
Goodpasture's syndrome is a rare vasculitis associated with anti-glomerular basement membrane (anti-GBM) autoantibodies that target type IV collagen found in the basement membranes of glomeruli and alveoli. We present a case of a 79-year-old man with seronegative Goodpasture's syndrome with predominant respiratory symptoms and mild acute kidney injury that initially improved. Final diagnosis was made by immunofluorescent staining on open lung biopsy which also revealed concomitant organising pneumonia. The patient underwent treatment with corticosteroids, cyclophosphamide, haemodialysis and plasmapheresis. This was an atypical presentation wherein the patient only exhibited pulmonary symptoms early in the course of illness in the setting of negative anti-GBM antibody serum testing, which made diagnosis challenging. With this case, we emphasise that clinicians should have a high suspicion for Goodpasture's syndrome in the setting of unexplained severe pulmonary or renal disease despite negative anti-GBM antibody testing.