Acute plasmacytic interstitial nephritis in a child with Down syndrome

A 7.5-year-old boy with Down syndrome presented in acute renal failure (ARF ) needing dialysis. When 1.5 years old he had a neuroblastoma, was treated for 1 year with chemotherapy and radiotherapy, and off chemotherapy had sin ce been in remission. Renal biopsy revealed an interstitial inflammation, p rincipally of plasma cells with some lymphocytes and eosinophils. Immunoflu orescence showed no deposition of immunoglobulins or complement (C3). The p lasma cells were a mixture of kappa and lambda light chain-producing cells. The patient spontaneously improved a week after admission. Initial ultraso nography showed enlarged kidneys with loss of corticomedullary differentiat ion. We are unaware of a report of ARF in a child, resulting primarily from a polyclonal plasmacytic interstitial nephritis. The etiology remains uncl ear.