According to the ISN/RPS classification, what finding distinguishes class III lupus nephritis from class IV lupus nephritis?
- A Presence of wire-loop deposits only in class IV
- B Active or inactive focal and segmental endocapillary or extracapillary involvement in fewer than 50 percent of glomeruli in class III versus 50 percent or more in class IV ✓
- C Purely mesangial deposits confined to the stalk in both classes
- D Presence of tubuloreticular inclusions exclusively in class III
Correct answer: B. Active or inactive focal and segmental endocapillary or extracapillary involvement in fewer than 50 percent of glomeruli in class III versus 50 percent or more in class IV
Explanation
The ISN/RPS scheme grades lupus nephritis by the proportion of glomeruli with active or chronic segmental or global lesions. Class III is focal lupus nephritis with fewer than 50 percent of glomeruli involved; class IV is diffuse lupus nephritis with 50 percent or more involved, subdivided into segmental and global forms. Wire loops occur in both classes and indicate large subendothelial deposits, so their presence alone does not define class IV. Mesangial-only disease is class I or II.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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