Lupus-related podocytopathy. Could it be a new entity within the spectrum of lupus nephritis?

Correspondence: Silvina Gutiérrez Centro de Microscopía Electrónica. Facultad de Ciencias Médicas. Universidad Nacional de Córdoba. Córdoba. Argentina. [email protected] [email protected] The classification of lupus nephritis was revised by the ISN/RPS in 2003. The increasingly recognized phenomenon of apparent minimal change disease (MCD) in the context of systemic lupus erythematosus (SLE), is not accepted in the above classification and is associated to a recent new pathological entity called lupus podocitopathy. A 32-year-old caucasian woman presented with arthralgia and swelling of the face, hands, and legs. Physical exam revealed pretibial edema and a patch of skin thickening on the left flank, consistent with morphea. Blood presure was 130/70mmHg; proteinuria 4.5g/dl; serum creatinine 0.9mg/dl; and albumin 2g/dl. Urinalysis revealed fat casts. Serology was negative for hepatitis B, C, HIV-1 and HIV-2. ANA titer was 1/1300, C3 70mg/dl and anti ds-DNA was elevated. There was no history of nonsteroidal anti-inflammatory drug use in the patient. A diagnosis of SLE was made. Sections from the needle renal biopsy showed cortex with 10 normocellular glomeruli with mild mesangial hypercellularity and mesangial matrix increased. There were no evident tubular, interstitial, and vascular lesions (Figure 1 A). Immunofluorescence microscopy revealed mesangial granular deposition of IgG (2+) (Figure 1 B), IgA (1+), IgM (1+), C3 (2+) (Figure 1 C) and C1q (3+) (Figure 1 D). Ultrastructural analysis showed diffuse effacement (~80%) of the epithelial cell food processes and vacuoles (Figure 2 A). Moreover few electron-dense deposits were noted in mildly expanded mesangium (Figure 2 B). Subepithelial or subendothelial deposits were not observed in the biopsy. Numerous tubulorreticular inclusions within endothelial cells of glomerular capillary were also seen (Figure 2 C). A diagnosis of lupus podocytopathy and lupus nephritis Figure 1. Light microscopy and immunofluorescence findings. (A) There are mild mesangial hypercellularity and variable increase in mesangial matrix (PAS). Immunofluorescence microscopy shows deposits of IgG (B); C3 (C) and C1q (D) confined to the mesangium. Bars=25μm.