IgA nephropathy histologically resembling focal-segmental glomerulosclerosis: a clinicopathologic study of 18 cases.

IgA nephropathy (IgAN) may present with several histologic patterns, including lesions resembling primary focal-segmental glomerulosclerosis (FSGS). To examine the clinical significance of these lesions, slides from all cases of IgAN diagnosed in our renal biopsy service between 1980 and 1994 for which diagnostic materials were available were reviewed. Eighteen of the 244 cases (7.4%) reviewed showed focal and segmental glomerular sclerosis with capillary collapse, sometimes associated with an overlying "cap" of visceral epithelial cells, and no more than very mild glomerular hypercellularity limited to mesangial areas. All showed mesangial IgA as the major immunoglobulin present by immunofluorescence, and all showed mesangial electron-dense deposits ultrastructurally. The mean age (34.8 +/- 11.0 years [+/- SD]), gender distribution (72% male), and racial distribution (67% white, 17% Hispanic, 11% black, 6% Asian) among the 18 patients with FSGS-like IgAN were similar to those of patients in our population with other histologic lesions of IgAN. Notably, the racial distribution of these patients was different from that of our patients with primary FSGS (> 35% black). Seventy-one percent of patients with FSGS-like IgAN had hematuria, but only one patient had gross hematuria. Eighty-two percent had nephrotic-range proteinuria. The mean serum creatinine (1.6 +/- 1.2 mg/dL; n = 17) and urine protein (5.5 +/- 2.8 g/24 hr; n = 17) levels in these patients at the time of biopsy were not significantly different from mean levels in 42 previously studied patients with primary FSGS (Haas et al, Am J Kidney Dis 26:740-750, 1995). Follow-up data obtained for 11 patients with FSGS-like IgAN (mean follow-up, 70 +/- 25 months; range, 37 to 120 months) showed only one who progressed to end-stage renal failure, with dialysis initiated 74 months postbiopsy. However, renal survival in these 11 patients was not significantly greater than that in the previously studied cohort of primary FSGS patients.