Nephrotic syndrome due to immunoglobulin M mesangial glomerulonephritis preceding juvenile idiopathic arthritis.

The association between nephrotic syndrome and juvenile idiopathic arthritis have rarely been described in pediatric patients. We report a child with steroid-responsive nephrotic syndrome, with frequent relapses, who presented with a new relapse of nephrotic syndrome associated with arthritis and uveitis at 21 months in remission after treatment with chlorambucil. Juvenile idiopathic arthritis was diagnosed and kidney biopsy examination showed mesangial glomerulonephritis with immunoglobulin M deposits. To our knowledge, only 2 cases of nephrotic syndrome preceding juvenile idiopathic arthritis have been reported, one without histopathology assessment and the other with minimal change disease. Although mesangial glomerulonephritis with nephrotic syndrome and juvenile idiopathic arthritis could have been coincidental, the immune pathogenic mechanism accepted for both diseases suggests they could be related.