Focal Segmental Glomerulosclerosis (FSGS)
FSGS is the most common cause of nephrotic syndrome in adults (specifically African American and Hispanic populations). It is characterized by progressive scarring of the glomeruli.
1. Pathological Features
| Examination | Findings |
|---|---|
| Light Microscopy (LM) | Focal (some glomeruli) and Segmental (parts of glomeruli) sclerosis with hyalinosis. |
| Immunofluorescence (IF) | Often negative; may show focal IgM, C3, or C1q deposits in sclerotic areas. |
| Electron Microscopy (EM) | Diffuse podocyte foot process effacement (similar to MCD). |
2. Exam Must-Knows
- Primary vs. Secondary: Primary is idiopathic. Secondary causes include HIV, Heroin use, Sickle cell disease, and massive obesity.
- Prognosis: Generally poor; high rate of progression to chronic kidney disease (CKD) and often steroid-resistant.
- Collapsing Variant: A severe histological subtype often associated with HIV-associated nephropathy.
Pathology Board Hint: For board questions, if the patient is an adult with nephrotic syndrome, think FSGS. If they have a risk factor like HIV or IV drug use, FSGS is the highest-yield suspect.