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| Focal Segmental Glomerulosclerosis |
| Etiology •Focal segmental glomerulosclerosis is not one disease but a histologic pattern of injury seen on light microscopy in patients with nephrotic range proteinuria. •Focal segmental glomerulosclerosis may be idiopathic or may be seen as a consequence of reflux nephropathy, AIDS nephropathy; heroin/drug addiction, or compensatory hypertrophy/hyperfiltration. |
| Pathogenesis •Since focal segmental glomerulosclerosis is not a disease so much as a histologic consequence of several diseases processes, the initiating pathogenetic mechanisms are varied. The common element to cases of focal segmental glomerulosclerosis is injury manifested by sclerosis in the setting of nephrotic range proteinuria., |
| Epidemiology •Focal segmental glomerulosclerosis is not one disease but a histologic pattern of injury seen on light microscopy in patients with nephrotic range proteinuria. •Focal segmental glomerulosclerosis may be idiopathic or may be seen as a consequence of reflux nephropathy, AIDS nephropathy; heroin/drug addiction, or compensatory hypertrophy/hyperfiltration. •Immunogenetics: DR4. |
| General Gross Description •The kidneys in focal segmental glomerulosclerosis would show no gross abnormalities in the early phases of the disease. •As the disease progresses and more glomeruli become sclerosed, the parenchymal mass will decrease and the kidneys would appear small and shrunken. |
| General Microscopic Description •The histologic recognition of the disease is dependent on examining a number of glomeruli together. •Some of the glomeruli are normal and some show segmental sclerotic lesions. •The sclerotic lesions show solidification of segments of the tuft and is composed of collapsed capillary basement membranes, increased collagenous matrix and few if any viable endothelial and mesangial cells. •Some of the affected segments may show large hyaline deposits occluding previously patent capillary lumens. •Direct immunofluorescence studies show IgM and C3 in the affected sclerosed segments. •Electron microscopy shows collapsed basement membranes, excess mesangial matrix material and the hyaline deposits noted on light microscopy correspond to large electron dense material occupying the capillary luminal space, which may represent entrapped serum proteins. •Occasional foam cells may be encountered in the sclerosed segments. •The tubular compartment will show tracts of atrophic tubules, paralleling the degree of glomerulosclerosis. |
| Clinical Correlation •Patients with focal segmental glomerulosclerosis manifest heavy proteinuria (3.5 gm or more per 24 hours) and the consequence of protein loss (hypoalbuminemia, hyperlipidemia, edema). •Additional complications of heavy proteinuria include increased vulnerability to infections, increased risk of thrombotic and thromboembolic diseases. •Depending on the stage of the disease, patients may show normal renal function, varying degrees of renal insufficiency, or renal failure. |
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 952-954. •Rose B. Renal Pathophysiology the essentials. Baltimore: Williams and Wilkins. 1994. Ch. 9. |
| Focal Segmental Glomerulosclerosis |
| Synopsis by: Harold Yamase M.D. (T71200M00003)[212] |
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