Class V lupus nephritis is called?
**Core Concept**
Class V lupus nephritis is a histopathological classification of lupus nephritis, characterized by diffuse glomerular proliferative lesions with significant involvement of the tubulointerstitium. It is also known as membranous lupus nephritis.
**Why the Correct Answer is Right**
Class V lupus nephritis is characterized by the deposition of immune complexes on the subepithelial side of the glomerular basement membrane, leading to thickening and alterations in the membrane's structure. This results in a membranous pattern of injury, which is distinct from the proliferative and sclerosing changes seen in other classes of lupus nephritis. The involvement of the tubulointerstitium in Class V lupus nephritis contributes to its significant clinical manifestations, including proteinuria and renal failure.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because membranous lupus nephritis is characterized by subepithelial immune complex deposition, not mesangial or endocapillary proliferation.
**Option B:** This option is incorrect because focal lupus nephritis (Class III) is characterized by segmental glomerular involvement, not diffuse involvement of the tubulointerstitium.
**Option C:** This option is incorrect because membranoproliferative lupus nephritis (Class III) is characterized by mesangial and endocapillary proliferation, not subepithelial immune complex deposition.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize the distinct histopathological features of Class V lupus nephritis, as it has a different prognosis and treatment approach compared to other classes of lupus nephritis.
**Correct Answer: D. Membranous lupus nephritis.**