Which of the following is the hallmark immunofluorescence pattern in post-streptococcal glomerulonephritis (PSGN)?
A. Linear IgG deposition along the glomerular basement membrane
B. Negative immunofluorescence with electron-dense deposits on electron microscopy
C. IgA-dominant deposition in the mesangium
D. Granular IgG and C3 deposition in a 'starry sky' pattern
Explanation
Immunofluorescence Pattern in PSGN
Key Point
Post-streptococcal glomerulonephritis (PSGN) is characterized by a granular pattern of IgG and C3 deposition on immunofluorescence microscopy, often described as a "starry sky" or "lumpy-bumpy" appearance.
Pathophysiology
PSGN is an immune complex-mediated glomerulonephritis that develops 1–3 weeks after a Group A Streptococcal (GAS) infection (pharyngitis or impetigo). The immune complexes deposit in the glomeruli, activating complement via the classical pathway.
Light Microscopy Findings
Diffuse proliferative glomerulonephritis
Hypercellularity (endocapillary proliferation)
Crescent formation (in severe cases)
Subepithelial "humps" on electron microscopy (pathognomonic)
Immunofluorescence Pattern
Table
Feature
Finding
IgG
Granular deposition
C3
Granular deposition (often more prominent than IgG)
Pattern
"Starry sky" or "lumpy-bumpy"
Location
Subepithelial, subendothelial, and mesangial
High-YieldNEET PG
The granular C3-dominant pattern is the most characteristic finding and helps distinguish PSGN from other forms of acute glomerulonephritis.
Clinical Correlation
Presents with hematuria, proteinuria, hypertension, and edema
Most cases resolve spontaneously in children; adults may have residual renal dysfunction
Prognosis is generally favorable with supportive care
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