Minimal Change in Nephrotic Syndrome Associated with Mixed Connective Tissue Disease

Abstract

Mixed connective tissue disease (MCTD) is a rheumatologic disorder that has combined features of systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis with the anti-U1 ribonucleoprotein (RNP) antibody. Although renal involvement is not included in any of the diagnostic criteria, it has been observed in 20% of MCTD patients. The most common renal disease is immune complex nephropathy, histologically classified as membranous glomerulonephritis, but minimal change disease (MCD) is very rare and has only been reported once previously. A previously healthy 33-year-old woman presented with generalized edema, puffy hands, arthralgia, and Raynaud’s phenomenon. We diagnosed MCD with proteinuria (> 9 g/day) and hypoalbuminemia (< 1.0 g/dL) by renal biopsy, and MCTD with a simultaneously high titer of the anti-U1 RNP antibody. The patient was treated with 200 mg/day cyclosporine and 30 mg/day prednisolone. The proteinuria and hypoalbuminemia normalized 2 months later. We report a patient with severe MCD associated with MCTD.