LAUSR

Pseudomelanosis duodeni (PD) is a rare benign condition first described as “melanosis duodeni” and refers to a rare endoscopic appearance of discrete speckled black pigmentation of duodenal mucosa. A 61-year-old male underwent endoscopy-guided duodenal biopsy to rule out celiac disease. He had a past history of chronic renal failure and was treated with hemodialysis. Histopathological examination of duodenal biopsy revealed tall villi with maintained crypt-to-villous ratio. There was no increase in intraepithelial lymphocytes. In the lamina propria there was a striking finding of brown black pigment–laden macrophages (Figure 1). The pigment was strongly positive for Perl’s Prussian blue stain (Figure 1, inset) indicating the presence of iron. Pseudomelanosis duodeni was first described by Bisordi and Kleinman in 1976 as “melanosis duodeni,” since the real nature of the black-brown pigmentation of the mucosa had not been further investigated. The pigment, originally interpreted as melanin, pseudomelanin, lipomelanin, or hemosiderin, has now been demonstrated to be mostly ferrous sulfide with small amounts of other elements. This is in contrast with melanosis coli where the pigment is lipofuscin. The pigment is usually located in the lysosomes of mucosal macrophages. Although the mechanism an d clinical significance remain unclear, the pathogenesis could be related to iron deposition secondary to intramucosal hemorrhage or impaired intramucosal iron transport after oral ferrous sulfate supplementation. PD is believed to be associated with certain diseases such as chronic heart failure, chronic renal failure, hypertension, diabetes mellitus, gastrointestinal bleeding, and the use of certain drugs, such as ferrous sulfate, hydralazine, propranolol, thiazide, furosemide, methyldopa, and digoxin. There is no known association with the use of laxatives. PD per se does not cause any symptoms. Unlike iron or other heavy metal deposits elsewhere in the body, which may develop a fibro-inflammatory reaction, PD has not been proved to cause fibrosis, stricture, or erosive duodenitis.