Membranous glomerulonephritis

1. Membranous Glomerulopathy
Membranous
Glomerulonephritis
Membranous nephropathy
Membranous nephritis
Lecture 42

2. Membranous GN
•This is a slowly progressive disease,
• most common between 30 & 50 years of age
•Usually caucasian.
•Well developed cases show
diffuse thickening of the capillary
wall.

3. Membranous
Glomerulonephritis
•It is the second most common cause of
nephrotic syndrome in adults, with
focal segmental glomerulosclerosis (FSGS)
being the most common.
Types: Primary & Secondary

4. Primary/idiopathic
85% of MGN cases are classified as
primary membranous glomerulonephritis—
that is to say, the cause of the disease is
idiopathic (of unknown origin or cause). This
can also be referred to as idiopathic
membranous nephropathy .

5. Secondary MGN
The remainder (15%) is secondary due to:
1.autoimmune conditions (e.g.,
systemic lupus erythematosus)
2.infections (e.g., syphilis, malaria, hepatitis B)
3.drugs (e.g., captopril, NSAIDs, penicillamine,
probenecid).
4.inorganic salts (e.g. gold, mercury).
5.tumors, frequently solid tumors of the lung and
colon.

6. Pathogenesis
•MGN is caused by immune complex formation
in the glomerulus. The immune complexes are
formed by binding of antibodies to antigens in
the glomerular basement membrane.
•The antigens may be part of the basement
membrane, or deposited from elsewhere by
the systemic circulation.

7. Pathogenesis
•The immune complex serves as an activator
that triggers a response from the C5b - C9
complements, which form a
membrane attack
complex
(MAC) on the
glomerular epithelial cells.

8. Pathogenesis
•MAC, in turn, stimulates release of
proteases and oxidants by the
mesangial and epithelial cells,
damaging the capillary walls and causing
them to become "leaky".

9. Pathogenesis
•
In addition, the epithelial cells also
seem to secrete an unknown
mediator that reduces nephrin
synthesis and distribution.

10. Morphology
• LM: Diffuse thickening of the GBM
•EM: Subepithelial deposits (“Spike & dome”
pattern)
•Effacement of foot processes
•Immunofluorescence microscopy:
Granular deposits

13. LM: The capillary loops are thickened and prominent, but the cellularity is not increased.

18. Clinical Presentation
•Some patients may present as
nephrotic syndrome with proteinuria, edema
with or without renal failure.
•Others may be asymptomatic and may be
picked up on screening or urinalysis as having
proteinuria.
•A definitive diagnosis of membranous
nephropathy requires a kidney biopsy.

19. Clinical Course
•Nephrotic syndrome
•Nonselective proteinuria
•Does not respond to corticosteroids
•Variable & Indolent course

20. Treatment
•Treatment of secondary membranous
nephropathy is guided by the treatment of
the original disease.
•For treatment of idiopathic membranous
nephropathy, the treatment options include
immunosuppressive drugs and non-specific
anti-proteinuric measures.

21. Prognosis
•1/3 have spontaneous remission,
•1/3 progress to require dialysis and
•1/3 continue to have proteinuria, without
progression of renal failure.