Immune-mediated protein-losing enteropathy with Down syndrome.

A 28-year-old woman previously diagnosed to have Down syndrome presented with a one-month history of severe hypoalbuminemia, lower extremity edema, and diarrhea. Her urine was negative for protein. She was diagnosed with immune-mediated protein-losing enteropathy (PLE) based on clinical findings, protein loss evident on (99m)Technetium-labeled human serum albumin scintigraphy, and IgM and complement C3 deposition in the duodenum. She did not exhibit any manifestations of collagen diseases. A dramatic remission was achieved and maintained with corticosteroid administration. This is the first report of immune-mediated PLE in a patient with Down syndrome.