Question

A 14-year-old girl with SLE presents with edema and nephrotic-range proteinuria. Renal biopsy shows diffuse thickening of the glomerular basement membrane without proliferative lesions. This corresponds to which class of lupus nephritis?

• A. Class I
• B. Class II
• C. Class III
• D. Class V

Hint:

Quick ISN/RPS classification summary: Class I = Minimal mesangial, Class II = Mesangial proliferative, Class III = Focal ($<50\%$), Class IV = Diffuse ($\ge 50\%$), Class V = Membranous (thick GBM, nephrotic), Class VI = Sclerotic ($\ge 90\%$).

Answer 1

The Correct Option is D

Concept:
Lupus nephritis is categorized according to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) histological classification into six distinct classes based on the pattern and extent of glomerular involvement.
Class V lupus nephritis represents membranous nephropathy, which typically presents clinically with marked proteinuria and full-blown nephrotic syndrome.
Explanation:
• Class I (Minimal mesangial lupus nephritis): Normal glomeruli on light microscopy, with mesangial immune deposits on immunofluorescence.

• Class II (Mesangial proliferative lupus nephritis): Purely mesangial hypercellularity with mesangial immune deposits, without subendothelial deposits.

• Class III (Focal lupus nephritis): Active or inactive endocapillary or extracapillary glomerulonephritis involving $<50\%$ of all glomeruli, usually presenting with nephritic features and active sediment.

• Class IV (Diffuse lupus nephritis): Involves $\ge 50\%$ of glomeruli with marked proliferative and necrotizing lesions, often showing wire-loop lesions and the worst renal prognosis.

• Class V (Membranous lupus nephritis): Characterized by diffuse thickening of the glomerular basement membrane (GBM) due to continuous global or segmental subepithelial immune deposits (demonstrating "spikes" on silver stain) without significant endocapillary proliferation.

• Class VI (Advanced sclerosing lupus nephritis): Global sclerosis of $\ge 90\%$ of glomeruli, representing end-stage scarring.
Final Answer:
Diffuse thickening of the glomerular basement membrane without proliferative lesions in a patient presenting with nephrotic-range proteinuria is the histological hallmark of Class V (Membranous) Lupus Nephritis.