Renal Path Review 3

Question 1

entities presenting as RPGN are associated with ? on biopsy

Answer 1

*glomerular crescent formation

Question 2

anatomical pattern of a crescentic glomerulonephritis

Answer 2

1. crescent fibrosis
2. proliferating capsular epithelial cells
3. compressed capillary tuft
4. early tuft fibrosis

Question 3

sign of acute glomerular inflammation

Answer 3

*fibrinoid necrosis (necrosis & fibrin deposition)
*stains “angry red” on trichrome stain
*pattern becomes crescentic & necrotizing glomerulonephritis

Question 4

biopsy findings of anti-GBM disease

Answer 4

*light microscopy: crescents on light microscopy
*immunofluorescence: LINEAR staining in capillary wall/GBM

Question 5

biopsy findings of Goodpasture’s Sydrome

Answer 5

*findings of anti-GMB disease in the kidney (linear staining in capillary wall/GBM on immunofluorescence) PLUS INTRAALVEOLAR HEMORRHAGES on lung biopsy

Question 6

c-ANCA

Answer 6

*anti-proteinase 3 circulating antibody (PR3 ANCA)
*more common in GPA

Question 7

p-ANCA

Answer 7

*anti-myeloperoxidase antibody (MPO-ANCA)
*more common in isolated pauci-immune glomerulonephritis (EGPA, MPA)

Question 8

biopsy findings of ANCA diseases (systemic vasculitides: GPA, EGPA)

Answer 8

*crescentic and necrotizing glomerulonephritis with “starburst pattern” fibrinoid necrosis of an artery
*VASCULITIS & ARTERIAL DAMAGE
*nothing seen on immunofluorescence (pauci-immune)

Question 9

GPA lung biopsy findings

Answer 9

*necrosis & GRANULOMAS and “giant cells” (multinucleated macrophages) seen on lung biopsy

note - granulomas are not seen in the kidney in GPA

Question 10

biopsy findings of lupus nephritis

Answer 10

*PAS stain: endocapillary hypercellularity
-focal if < 50% of glomeruli are involved (class III LN)
-diffuse if > 50% of glomeruli are involved (class IV LN)

*trichrome stain: mesangial immune complexes + “wire loops” (subendothelial immune complexes)

*immunofluorescence: “full house” immune complex deposition in mesangial and capillary walls (all immunoglobulins [IgG, IgA, IgM] and both complement components [C3 and C1q] stain +)

Question 11

process for diagnosis of lupus nephritis

Answer 11

*light microscopy establishes the pattern of glomerulonephritis
*immunofluorescence & electron microscopy are diagnostic for lupus nephritis
*electron microscopy determines the location of immune complexes
*glomerulonephritis pattern and location of immune complexes determine the CLASS of lupus nephritis
*the class of lupus nephritis guides the treatment

Question 12

biopsy findings of class V lupus nephritis

Answer 12

*“full house” immunofluorescence
*immune complex deposition: GRANULAR deposition on the capillary walls and mesangium; may also be subendothelial

Question 13

contrast membranous nephropathy vs. class V lupus nephritis (membranous)

Answer 13

*membranous nephropathy:
-LM: spikes & domes, no inflammation
-IF: immune complexes on capillary walls
-EM: subepithelial immune complexes

*class V lupus nephritis:
-LM: spikes & domes, no inflammation
-IF: immune complexes on capillary walls, plus a few in mesangium and under the endothelium
-EM: subepithelial immune complexes, a few subendothelial and mesangial

Question 14

ddx of RPGN etiologies - contrast findings

Answer 14

1. anti-GBM:
   -IF: linear capillary wall IgG
   -serology: positive anti-GBM antibody
2. ANCA glomerulonephritides:
   -IF: no granular deposits
   -serology: positive ANCA antibody
3. immune complex glomerulonephritis:
   -IF: granular immune complex deposits
   -serology: ANA positive, anti-dsDNA, ASO