Pseudomelanosis duodeni: case report.

Pseudomelanosis duodeni is a rare benign condition. It manifests endoscopically as discrete, flat, small brown-black spots in the duodenal mucosa. It produces no symptoms and may be reversible. The cause and natural history of the pigmentation have not been clarified, although it is associated with a variety of systemic illnesses and medications. With electron microscopy and electron-probe energy dispersive X-ray analysis, the pigment corresponds principally to an accumulation of ferrous sulfide (FeS) in macrophages within the lamina propria. We report the case of a 56-year-old female patient with a past history of diabetes mellitus and hypertension. She was admitted because of nausea, vomiting, and diarrhea and underwent esophagogastroduodenoscopy because of stool occult blood test results of 3+. Endoscopy revealed diffusely scattered black spots in the bulb and second portion of the duodenum. Histological examination showed numerous pigment-laden macrophages in the lamina propria of mucosal villi. The diagnosis requires further confirmation by electron microscopy and electron-probe energy dispersive X-ray microanalysis. No special therapy is indicated for this rare lesion.