Evolution of immunoglobulin A nephropathy into Henoch-Schönlein purpura in an adult patient.

We report the first case of the evolution of immunoglobulin A (IgA) nephropathy into Henoch-Schönlein purpura in an adult patient. A 28-year-old man presented with an episode of gross hematuria and acute renal failure. The serum IgA level was increased and renal biopsy findings were diagnostic of IgA nephropathy. In addition, many renal tubuli were filled by red blood cell casts and presented a marked tubular necrosis. Coincidental with the disappearance of gross hematuria, renal function progressively improved. The patient continued to have microhematuria, normal renal function, and isolated bouts of macroscopic hematuria. Ten years later, the patient developed arthralgias, a purpuric rash in the legs, gross hematuria, and an elevated serum creatinine level. A skin biopsy showed leukocytoclastic vasculitis with IgA deposits. The renal biopsy showed histologic lesions very similar to those observed in the first biopsy 10 years before: mesangial proliferation with mesangial deposition of IgA and tubular necrosis with obstruction of renal tubuli by red blood cell casts. The serum creatinine level returned to normal. Recurrent episodes of purpura associated with macroscopic hematuria persisted during the follow-up, but without worsening of renal function. An interesting feature of our patient was the development of reversible renal failure associated with macroscopic hematuria on two different occasions. Although this complication has been described in IgA nephropathy, it has been rarely reported in Henoch-Schönlein purpura. It is possible that IgA nephropathy and Henoch-Schönlein purpura are different clinical manifestations of the same disease and probably share a common pathogenesis. Our case is a demonstrative example of this hypothesis.