genitourinary disorders
Focal Segmental Glomerulosclerosis
Diagnosis of Focal Segmental Glomerulosclerosis
Renal biopsy, when possible, with immunostaining and electron microscopy Focal segmental glomerulosclerosis (FSGS) is suspected in patients with nephrotic syndrome, proteinuria, or renal dysfunction with no obvious cause, particularly patients who have disorders or use illicit drugs or medications associated with FSGS. Urinalysis is done and bloodureanitrogen (BUN), serum creatinine, and 24-hour urinary protein excretion or spot urinary protein:creatinine ratio are measured. Diagnosis is confirmed by Renal biopsy , which shows focal and segmental hyalinization of the glomeruli, often with immunostaining showing IgM and complement (C3) deposits in a nodular and coarse granular pattern. Electron microscopy reveals diffuse effacement of podocyte foot processes in idiopathic cases but may show patchy effacement in secondary cases. Global sclerosis may be visible, along with secondary atrophic glomeruli. Biopsy may be falsely negative if areas of focal abnormalities are not sampled. The top image shows the right side of the glomerulus. The glomerulus, which is segmentally sclerotic, is composed of obliterated capillary lumens and an increased amount of mesangial matrix. The rest of the glomerulus is normal (Jones silver stain,×400). In the bottom image, hyalin, defined as smooth, glassy-appearing material, results from insudation (the opposite of exudation) of plasma proteins. It occurs frequently and is not diagnostic (Jones silver stain,×400). Image provided by Agnes Fogo, MD, and the American Journal of Kidney Diseases'Atlas of Renal Pathology(see www.ajkd.org). Immunofluorescence staining with anti-IgM demonstrates IgM in mesangium or in areas of hyalinosis (smooth, globular staining on right). IgM is thought to become trapped in areas of expanded mesangium and sclerosis (×200). Image provided by Agnes Fogo, MD, and the American Journal of Kidney Diseases'Atlas of Renal Pathology(see www.ajkd.org). Extensive blunting and effacement of foot processes can be seen on transmission electron microscopy (×3000). Image provided by Agnes Fogo, MD, and the American Journal of Kidney Diseases'Atlas of Renal Pathology(see www.ajkd.org). The central glomerulus in this biopsy specimen demonstrates global sclerosis. The finding is nonspecific and may develop in response to injury or aging (Jones silver stain,×100). Image provided by Agnes Fogo, MD, and the American Journal of Kidney Diseases'Atlas of Renal Pathology(see www.ajkd.org). A tip lesion is segmental sclerosis localized to the glomerular pole where the tubule originates. It may be a marker of improved prognosis (Jones silver stain,×200). Image provided by Agnes Fogo, MD, and the American Journal of Kidney Diseases'Atlas of Renal Pathology(see www.ajkd.org). 