Focal segmental glomerulosclerosis (FSGS)

Focal segmental glomerulosclerosis is a disease of unknown aetiology. It is particularly prone to recur in kidneys transplanted into affected individuals, sometimes within days of transplantation. A circulating factor may be involved. It presents as proteinuria or nephrotic syndrome and is usually resistant to steroid therapy. All age groups are affected.

On light microscopy, segmental glomerulosclerosis is seen, which later progresses to global sclerosis. The deep glomeruli at the corticomedullary junction are affected first. These may be missed on transcutaneous biopsy, leading to a mistaken diagnosis of a minimal-change glomerular lesion.

In addition, some believe that a pathogenetic link exists between minimal-change nephropathy and focal glomerulosclerosis, and that a proportion of cases classified as having the former condition develop progressive renal impairment.

Immunofluorescence may show deposits of C3 and IgM in affected portions of the glomerulus, but non-specific fixation to damaged tissue, rather than immune complex deposition, may well be the explanation for this.

About 50% of patients progress to end-stage renal failure within 10 years of diagnosis.