Pseudomelanosis duodeni, speckled black pigmentation of the duodenal mucosa, 
presents a striking appearance at endoscopy. Among the 14 reported cases there 
is a predominance of black women greater than 40 years old, but it can occur in 
any race and age group. There is no known association with pigmentation 
elsewhere in the gastrointestinal tract or with the use of laxatives. However, 
most reported patients were hypertensive (many treated with hydralazine and 
propranolol) and significant numbers suffered from upper gastrointestinal 
bleeding, chronic renal failure, or diabetes mellitus. The pigment is usually 
located in mucosal macrophages, in lysosomes. Histochemical studies and electron 
probe microanalysis suggest that several pigments may result in this endoscopic 
appearance, including lipomelanin, ceroid, iron sulfide, and hemosiderin. 
Additional studies, possibly using tissue from surgical resections or autopsies, 
are needed to determine the etiology and clinical significance of this 
heterogeneous entity.