Fever of unknown origin secondary to type I crescentic glomerulonephritis and anti-SCl 70 antibodies without clinical manifestations of systemic sclerosis.

A 57-year-old woman presented with fever and cellulitis of the right leg. Urinalysis and kidney function were normal on admission. Cellulitis remitted but fever persisted for six weeks. X-ray imaging, cultures, serological assays for viruses and autoimmunity did not reveal the cause of fever. Unexpectedly anti-Scl 70 (anti-topoisomerase I) antibodies were positive. A skin biopsy ruled out scleroderma. On the fifth hospitalization week kidney function declined in association with hematuria, leucocyturia, and proteinuria. Prednisone was administered due to clinical suspicion of drug-induced interstitial nephritis. Fever declined in 24 h, but renal failure became rapidly worse requiring hemodialysis. Kidney biopsy revealed extensive crescentic glomerulonephritis (CGN), with much glomerular destruction, with an IgG-positive linear pattern on immunofluorescence microscopy. No overtly active microangiopathy or vasculitis were present. There was no pulmonary involvement and anti-glomerular basement membrane antibodies were not detected in the serum. After one year anti-Scl 70 antibodies were still positive without scleroderma manifestations and 17 months later the patient received a kidney transplant with excellent results. Presentation of type 1 CGN as a fever of unknown origin (FUO) is exceptional. Anti-Scl 70 antibodies are highly specific for scleroderma and are seldom present in other diseases. As far as we are aware there are no published cases of the association of type 1 CGN with anti-Scl 70 antibodies.