FGS accounts for 10% to 15% of children and 15% to 20% of adults with idiopathic nephrotic syndrome .
Although heavy and edema are usually present at onset, some patients have asymptomatic proteinuria and azotemia, and microscopic hematuria are commonly found at the time of diagnosis. Serum complement levels are normal.
Recently, a glomerular permeability factor present in the blood has been implicated in the proteinuria in patients with FGS. Light shows focal and segmental collapse of capillary loops and mesangial sclerosis sometimes associated with hyalin insudation at the edge of the sclerotic focus. Proliferation or infiltration is absent. Focal mild tubular dropout with interstitial fibrosis is often present. Patchy deposition of IgM, C3, and occasionally other immunoreactants is seen in the segmental sclerotic foci. Electron-dense deposits are typically absent by electron microscopy. Patients with acquired immunodeficiency FGS often show numerous tubuloreticular structures within the endothelial cytoplasm collections of microtubules that apparently form in response to elevated serum levels of interferon. Such structures are also very common in biopsies of patients with SLE. Approximately one third of patients respond to corticosteroid therapy with a lasting remission and good long-term renal function. But most(60% to 70%), particularly those with persistent nephrotic syndrome, progress to chronic renal failure(55% by 10 years). remainder follow a long-term course with relapses and remissions and late onset of renal failure. Recurrence of FGS in transplants occurs in as many as 40% of patients.
Heroin users and patients with the acquired immunodeficiency syndrome may develop the nephrotic syndrome and the histologic lesion of FGS. These patients typically follow a much more rapid downhill course, of ten with progression to end-stage renal failure in less than 1 year. A variant of FGS known as”collapsing glomerulopathy” is a distinct entity characterized by lack racial predominance, massive proteinuria, relatively rapidly progressive renal insufficiency, and distinctive pathologic findings.
Although collapsing glomerulopathy resembles human immunodeficiency virus both pathologically and clinically, it differs clinically by having evidence for associated human immunodeficiency virus infection and differs pathologically by lacking endothelial or tubuloreticular inclusions.