A Rare Case of C3 Glomerulonephritis Presenting as Pulmonary Renal Syndrome

C3 glomerulonephritis (C3GN) is a rare disease that falls under the umbrella of C3 glomerulopathy (C3G). Classic manifestations of C3G include acute renal failure, proteinuria, and hematuria. In some cases, extrarenal manifestations can include ocular drusen. Until recent reports, C3G manifesting with pulmonary symptoms has not been reported. In this report, we describe a patient that initially presented with hemoptysis and acute renal failure, eventually leading to a diagnosis of pulmonary renal syndrome. Renal biopsy showed C3GN. The patient’s symptoms improved with pulse dose steroids, plasmapheresis and mycophenolate mofetil. C3G presenting with pulmonary symptoms is rare. Further research is needed to understand the mechanism of complement deposition in the lung parenchyma and to determine a standard therapy to treat these patients. Clinicians should be aware of the potential pulmonary manifestations that can be caused by C3GN.