HISTOLOGIC SUBCLASSIFICATION OF IGA NEPHROPATHY - A CLINICOPATHOLOGICAL STUDY OF 244 CASES

IgA nephropathy (IgAN) may present with a wide variety of histologic p atterns on renal biopsy, ranging from a minimal lesion to a diffuse pr oliferative glomerutonephritis (GN). The histologic features of 244 ca ses of IgAN (not including Schonlein-Henoch nephritis) diagnosed betwe en 1980 and 1994 were reviewed, and each case was subclassified using the following, relatively simple histologic classification schema: sub class I (39 cases): minimal or no mesangial hypercellularity, without glomerular sclerosis; subclass II (18 cases): focal and segmental glom erular sclerosis without active cellular proliferation; subclass III ( 110 cases): focal proliferative GN; subclass IV (42 cases): diffuse pr oliferative GN; and subclass V (35 cases): any biopsy showing greater than or equal to 40% globally sclerotic glomeruli and/or greater than or equal to 40% estimated cortical tubular atrophy or loss. Subsequent analysis of renal survival in 109 patients who underwent biopsy befor e or during 1992 for whom such data were available showed a strong, st atistically significant correlation between histologic subclass and re nal survival, with an order I, II (greatest survival) > III > IV, V, C rescents were a significant negative prognostic indicator for renal su rvival in subclass III (but not in subclass IV), and interstitial expa nsion was a negative prognostic indicator in subclasses III and IV, al though the statistical significance of these were not maintained after controlling for serum creatinine at the time of biopsy, The presence of peripheral glomerular capillary deposits ultrastructurally had no p rognostic significance, With respect to clinical presentation, hyperte nsion (systolic blood pressure greater than or equal to 130 mm Hg and diastolic blood pressure greater than or equal to 90 mm Hg) and protei nuria of greater than or equal to 2.0 g/24 hr were significant negativ e prognostic indicators for renal survival, even when controlling for serum creatinine at the time of renal biopsy. The presence of gross he maturia correlated significantly with increased renal survival by univ ariate analysis, but not when controlling for serum creatinine at the time of renal biopsy, The findings of this study confirm the wide vari ety of clinical and histopathologic presentations of IgAN, and indicat e the utility of the proposed histologic classification schema in asse ssing a patient's likelihood of ultimately developing end-stage renal disease. (C) 1997 by the National Kidney Foundation, Inc.