Duodenal pseudomelanosis (or pseudomelanosis duodeni) is a rare benign condition 
characterized by black-brown speckled pigmentation of the duodenal mucosa. 
Collections of pigment-laden macrophages are found in the tips of duodenal 
villi. The pigment is thought to be mostly composed of ferrous sulfide. 
Histochemichal stains for iron (Perl's prussian blue) or melanin 
(Masson-Fontana) may be positive, but are usually negative or unpredictable. 
Duodenal pseudomelanosis occurs predominantly in middle-aged to old adults and 
more commonly in females. It is associated with chronic renal failure, arterial 
hypertension, diabetes mellitus and gastrointestinal bleeding. Medications such 
as ferrous sulfate, hydralazine, propranolol, hydrochlorothiazide and furosemide 
are thought to play a role as well. We report a case of a 86-year-old female who 
presented with a history of watery diarrhea and melena. The patient had a 
history of high blood pressure and ischemic stroke episodes. She was on multiple 
medication including hidralazine, captopril, hydrochlorthiazide and aspirin. She 
was dehydrated, her blood pressure was 96 × 60 mmHg and neurologic examination 
showed complete left hemiplegia with central VII nerve palsy. Laboratory tests 
showed normal serum electrolytes and renal function. Hemoglobin level was 10.7 
g%. An upper endoscopy showed multiple diminutive black spots throughout the 
distal duodenal bulb and second portion. Histology showed multiple foci of a 
brown-black granular pigment inside macrophages within the tips of the villi 
(pseudomelanosis). Stains for iron and melanin were negative. She was treated 
with omeprazol, parenteral fluid replacement with saline and partial fasting. 
After complete recovery she was discharged for ambulatory follow up.