IDIOPATHIC COLLAPSING FOCAL SEGMENTAL GLOMERULOSCLEROSIS - A CLINICOPATHOLOGICAL STUDY

A review of all native kidney biopsies at our center from 1974 to 1993 identified 43 cases of idiopathic focal segmental glomerulosclerosis (FSGS) with predominantly collapsing features and lacking evidence of HIV-1 infection or intravenous drug use. No case was identified before 1979 and the incidence of this entity has progressively increased ove r the past two decades. Compared to 50 age-matched controls of idiopat hic FSGS with typical perihilar scars, the group of idiopathic collaps ing FSGS displayed black racial predominance, a higher serum creatinin e and more severe features of nephrotic syndrome at biopsy. Morphologi c features of viseral epithelial cell hypertrophy and hyperplasia, tub ular microcysts, tubular epithelial degenerative and regenerative feat ures and interstitial edema were more prevalent and severe in collapsi ng FSGS. Median time to ESRD was rapid in collapsing FSGS versus contr ols (13.0 months vs. 62.5 months, P < 0.05). Correlates of progression to ESRD included a higher initial serum creatinine and failure to und ergo remission of proteinuria. Both glomerulosclerosis and certain fea tures of tubular damage were independent predictors of the level of re nal function at time of biopsy, but not of the rate of progression of renal insufficiency. Although three patients had partial or complete s pontaneous remissions, none of 26 patients treated with steroids alone responded. Idiopathic collapsing FSGS is a variant of FSGS with incre asing incidence, distinct clinicopathologic features, black racial pre dominance, a rapidly progressive course and relative steroid resistanc e.