Fibrillary glomerulonephritis in a patient with systemic lupus erythematosus: a rare association.

We report the case of a 28-year-old man with systemic lupus erythematosus (SLE) and rapidly progressive glomerulonephritis (RPGN) due to fibrillary glomerulonephritis (FGN). The patient had a history of SLE and had been treated with mycophenolate mofetil, prednisone, and intravenous cyclophosphamide for his renal and extra-renal manifestations. In spite of this treatment, he developed RPGN. A subsequent renal biopsy revealed diffuse proliferative glomerulonephritis with fibrillary deposits. SLE is rarely associated with FGN, however FGN should be considered in the differential diagnosis of any SLE patient with RPGN.