Predictive value of small crescents in IgA nephropathy: analysis of four patients showing a deteriorated renal function during a long follow-up period.

Four patients with IgA nephropathy developed a chronic renal failure during a long follow-up period ranging from three to 8.5 years (mean 6.4 years). All patients showed a normal renal function, normal blood pressure and mild proteinuria at the time of the first renal biopsy. The first biopsies showed focal mesangial proliferation with small cellular crescents in a small percentage of the observed glomeruli. No case showed sclerotic changes in the interstitium and vessels. In contrast, at the second biopsies, all of them exhibited a deteriorated renal function, hypertension and massive proteinuria. The second biopsies revealed marked sclerotic changes in the glomeruli, interstitium, and vessels with significant focal segmental glomerular sclerosis and adhesions. Since no established factors predisposing the patients to chronic renal insufficiency had been observed at the time of the first biopsy, it was suggested that small crescents, even if focal, should be regarded as indicating an unfavorable prognosis.