Focal segmental glomerulosclerosis (FSG) is a kidney disorder characterized by scarring of a portion of the glomeruli. It is the most common cause of nephrotic syndrome. FSG can be idiopathic or secondary to conditions like HIV, sickle cell anemia, or drug abuse. On microscopy, FSG shows sclerosis, hyalinosis, and diffuse effacement of podocyte foot processes. It causes non-selective proteinuria, reduced kidney function, and hypertension. A variant called collapsing glomerulopathy is seen in HIV patients and has a poorer prognosis. While treatment options are limited, children generally have a better outlook than adults.

1. Focal Segmental
Glomerulosclerosis
Venkatesh Karthikeyan,
Velammal Medical College

2. Focal Segmental
Glomerulosclerosis
Focal – Less than 50% glomeruli is affected
Segmental – involving a portion of glomerular tuft
Sclerosis – abnormal hardening
Commonest cause of nephrotic sydrome

4. Causes
Idiopathic
Secondary
Loss of renal tissue (unilateral renal agenesis,
advanced stages of reflux nephropathy,
hypertensive nephropathy)
Associated with conditions like sickle cell
anemia, HIV, Heroin abuse, obesity
Mutations in genes like nephrin, podocin(ARD),
alpha – actinin 4(ADD)

5. Hallmark feature
 Degeneration and focal disruption of visceral epithelial cells

6. Light Microscopy
Sclerosis (extracellular accumulation of
collagenous matrix in mesangium or capillary
loops or both)
Hyalinosis (extracellular accumulation of
homogenous and eosinophilic material in
glomeruli)

8. Electron Microscopy
 Diffuse effacement of foot process of podocytes

9. Immunofluorescence microscopy
 IgM and C3 may be seen in the sclerotic areas and in
mesangium

10. Clinical Features
 Non-selective proteinuria
 Reduction in GFR
 Hypertension
 Poor response to corticosteroids
 Recurrence common in transplant patients
 Children have better prognosis

11. Collapsing Glomerulopathy
 Variant of FSG
 Usually associated with HIV and cystinosis
 Poor prognosis
 Collapse and sclerosis of the entire glomerular tuft

12. Other variants of FSG
 Glomerular tip lesion variant
 Cellular variant
 Perihilar variant
 Not otherwise specific (NOS) variant

13. Take home points
 Hallmark of FSG is degeneration and focal disruption of
visceral epithelial cells
 Hyalinosis and sclerosis seen
 Commonest cause for nephrotic syndrome
 Collapsing glomerulopathy is a variant of FSG seen in HIV
patients
 No Immunoglobulin or complement deposits seen on
immunofluorescence microscopy in Minimal change disease
unlike FSG

14. Thank you 
Dr Richard Bright
Father of Nephrology
Dr KS Chugh
Father of Nephrology in India