Changing patterns in the histopathology of idiopathic nephrotic syndrome in children1

Changing patterns in the histopathology of idiopathic nephrotic The International Study of Kidney Disease in Children syndrome in children. (ISKDC) reported in the 1970s that minimal change ne- Background. It is widely accepted that minimal change ne- phrotic syndrome (MCNS) was the most common histo- phrotic syndrome (MCNS) is the most common cause of ne- logical lesion in renal biopsies from children with idio- phrosis in children. Recent studies have demonstrated an in- pathic nephrotic syndrome (1, 2). This observation was creasing incidence of focal segmental glomerulosclerosis (FSGS) confirmed by single centers that reported MCNS in al- in adults. Methods. To determine possible changes in the etiology of most 90% of cases (3). The same studies showed that childhood nephrosis, the clinical charts of 152 pediatric patients focal segmental glomerulosclerosis (FSGS) was a rare diagnosed with idiopathic nephrotic syndrome between 1978 cause of nephrosis in children, observed in only 5 to 7% and 1997 were reviewed. Histopathological diagnosis was avail- of the biopsies (1-3). More recent studies in adults have able in 105 patients. reported an increasing incidence of FSGS during the last Results. MCNS was present in 35% of all biopsies, whereas FSGS was observed in 31%. Even if we assume that all patients 20 years, accompanied by a significant decline in the without a histological diagnosis had MCNS (presumptive incidence of MCNS (4). D'Agati has suggested that FSGS MCNS), the total incidence of MCNS (biopsy proven 1 pre- constitutes the most common glomerulopathy observed sumptive) in our population was only 55%. We observed a among biopsies performed in adult native kidneys (5). dramatic increase in the incidence of FSGS during recent years. Unfortunately, in the pediatric population, the only stud- Before 1990, FSGS was diagnosed in 23% of all renal biopsies ies performed during the last 20 years have focused on but increased to 47% afterward (P 5 0.02). This pattern was observed in all ethnic groups. In African Americans, there was selected patient populations that were either steroid de- a trend for an increase in the incidence of FSGS from 38% pendent or frequent relapsers. In 1981, Siegel et al re- before 1990 to 69% after 1990. A similar trend was observed ported that FSGS was present in 29% of renal biopsies in Caucasians (from 20 to 45%) and Hispanics (from 8 to 33%). performed in children with steroid-dependent nephrotic Hispanics had the highest incidence of MCNS (biopsy proven 1 syndrome (6). Trachtman and colleagues later observed presumptive: 73%), followed by Caucasians (53%) and African Americans (37%). The mean age for presentation of nephrotic that MCNS was present in 25% of the biopsies per- syndrome in African Americans (8.0 6 0.9 years) was higher formed in pediatric patients with frequently relapsing, than in Caucasians (4.1 6 0.05) and Hispanics (3.3 6 0.5). steroid-sensitive nephrotic syndrome (7). Conclusions. Our study showed that the incidence of FSGS It has been our impression that the incidence of FSGS in children with idiopathic nephrotic syndrome has increased has increased in our practice during recent years. In recently. Furthermore, in African American children, FSGS is addition, in agreement with observations from other cen- the most common cause of nephrotic syndrome. These findings may have significant implications in the management of child- ters, we have observed a marked predominance of FSGS hood nephrotic syndrome.