Focal-segmental glomerulosclerosis. The relationship between tubular atrophy and segmental sclerosis

Biopsy specimens with focal-segmental glomerulosclerosis (FSGS) show segmental sclerosis (SS) and tubular atrophy (TA). The relationship between SS and TA was studied using serial sections. Based on the location of the SS, 3 and 5 biopsy specimens, respectively, were classified as FSGS, glomerular tip lesion (GTL) or FSGS, not otherwise specified (NOS). The proximal tubule was classified as normal or atrophic. The glomerulus was tracked through serial sections in both directions and classified as normal, SS (graded 1(+)-4+), or ischemic. Segmental sclerosis was identified in 21 of 24 glomeruli in FSGS, GTL and in 46 of 89 glomeruli in FSGS, NOS; TA was identified in 13 of 16 glomeruli in FSGS, GTL and 6 of 13 glomeruli in FSGS, NOS, which showed 1+ SS, and in 36 of 38 glomeruli in both forms, which showed 2+ to 3+ SS. Basement membrane disruptions at the glomerular-tubular junction and interstitial expansion with inflammation was encountered. Three biopsy specimens with FSGS, NOS had hypertensive changes and showed TA in several normal and in all ischemic glomeruli. Chronic tubular injury is present in most glomeruli containing segmental lesions, even small lesions, suggesting that the glomerular and tubular injury may have a common cause or that tubular injury may result from constituent(s) in the glomerular filtrate.