Tacrolimus Induction Therapy for Nephrotic Syndrome Caused by Minimal Mesangial Lupus Nephritis with Lupus Podocytopathy: A Case-Based Review

BACKGROUND Nephrotic syndrome caused by minimal mesangial lupus nephritis is considered rare. Nephrotic syndrome can be caused by minimal mesangial lupus nephritis with diffuse epithelial foot-process effacement and lupus podocytopathy. CASE REPORT A 23-year-old Japanese woman diagnosed with mixed connective tissue disease was admitted because of weight gain and generalized edema for 2 weeks prior to admission. She had butterfly-shaped erythema on her cheeks, proteinuria, leukocytopenia with lymphocytopenia, and hypoalbuminemia. She was positive for antinuclear antibodies, and specific autoantibodies were only positive for the ribonucleoprotein (RNP) antigen. She was diagnosed with systemic lupus erythematosus. Renal biopsy showed minor glomerular abnormalities, and immunofluorescence revealed peripheral deposits of IgM and complement C3c. Electron microscopy revealed diffuse podocyte foot-process effacement of >80% of the capillary loop surfaces, with only a few subendothelial deposits. Consequently, we diagnosed minimal mesangial lupus nephritis with lupus podocytopathy. On hospital day 4, we administered 1000 mg/day of methylprednisolone for 3 days, followed by prednisolone 50 mg/day, but proteinuria persisted. On day 12, we administered tacrolimus (3 mg/day). Proteinuria improved and then disappeared on day 17. Prednisolone was gradually tapered and stopped after 3 years, although tacrolimus 3 mg/day was continued. No flare-up was observed 4 years after admission. CONCLUSIONS Tacrolimus showed good efficacy in this case of minimal mesangial lupus nephritis with lupus podocytopathy. Prospective and randomized controlled trials should be conducted to demonstrate the efficacy of tacrolimus for this indication.