A 28-year-old man presents with cola-colored urine, periorbital edema, and hypertension 10 days after a sore throat. Urinalysis shows RBC casts and proteinuria. Serum creatinine is mildly elevated. All of the following are characteristic features of post-streptococcal glomerulonephritis (PSGN) EXCEPT:

Explanation

## Distinguishing PSGN from RPGN **Key Point:** Post-streptococcal glomerulonephritis (PSGN) is an acute proliferative glomerulonephritis, NOT a rapidly progressive glomerulonephritis (RPGN). The presence of crescents is NOT a typical or characteristic feature of PSGN. ## Pathologic Features of PSGN | Feature | Finding | |---------|----------| | **Light Microscopy** | Diffuse endocapillary proliferation; hypercellularity of glomeruli | | **Immunofluorescence** | Granular IgG and C3 deposits (immune complex) | | **Electron Microscopy** | Subepithelial 'hump' deposits (pathognomonic); electron-dense deposits | | **Crescent Formation** | Absent or minimal; NOT characteristic | ## Clinical Features of PSGN **High-Yield:** PSGN typically presents with: - Nephritic syndrome (hematuria, RBC casts, hypertension, edema) - Follows group A streptococcal pharyngitis or skin infection - Transient hypocomplementemia (↓C3, normal C4) - Self-limited course; most recover completely ## Why Crescents Are NOT Typical in PSGN **Clinical Pearl:** Crescents (extracapillary proliferation) are the hallmark of RPGN (ANCA-associated, anti-GBM disease, immune complex RPGN), not PSGN. While rare crescents may occur in severe PSGN, their presence in most cases would indicate a different diagnosis (e.g., ANCA-GN superimposed on PSGN or misclassification). **Warning:** Do not confuse acute proliferative GN (PSGN) with rapidly progressive GN (RPGN). The prognosis and treatment differ significantly.