Duodenal melanosis.

Melanosis duodeni is a rare benign condition that has only recently been recognized. We describe melanosis duodeni in a 64-year-old woman who had been taking propranolol and furosemide for 5 years. The cause and clinical significance of this unusual finding remain obscure. But we assume that it is an idiosyncratic metabolism of benzene-ring-containing drugs resulting in the accumulation of pigment in the duodenal mucosa.