Focal and segmental glomerular sclerosis
Focal and segmental glomerular sclerosis (FSGS) is a glomerular lesion which is associated with distinctive clinical features. Because it may be pathogenetically heterogeneous, it is not yet appropriate to call it a disease, yet its discovery in a renal biopsy in a patient with the nephrotic syndrome does have important connotations with respect to response to treatment and to long-term outcome. By light microscopy the characteristic finding is segmental areas of sclerosis (and hyalinosis) involving only some glomeruli. Patients with the FSGS lesion typically have proteinuria which is usually in the nephrotic range (〉3.5g/d in an adult), accompanied by the typical constellation of signs and symptoms of the nephrotic syndrome and arterial hypertension. A minority of patients may have only asymptomatic proteinuria and these patients usually do not progress to end-stage renal disease (ESRD) but the natural course of FSGS is ominous in most patients with nephrotic syndrome. However, numerous observational studies have shown that about 50–70% of patients may respond completely or partially to prolonged glucocorticoid therapy or other ‘immunosuppressive’ treatments and thus have a fair outcome in the long term.