Mysterious Black Crystalline Pigment in the Duodenum

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Introduction: Pigment deposit in small intestine is rare. Cases of melanosis-like or pseudomelanosis of the duodenum have been reported and usually associated with essential hypertension with patients taking antihypertensive medicines, chronic renal failure, or gastric bleeding. Melanin, lipofuscin, or hemosiderin deposits are pigments that may be contributing. We present a case of a rare black pigmentation of the duodenum. Case: 72 year-old African American female was seen in consultation for anemia and recent drop in hemoglobin. Although her INR was elevated at 4.5, she had no overt bleeding source. She has multiple co-morbidities including essential hypertension, chronic kidney disease, history of left colon cancer status post resection with no chemotherapy or radiation therapy, and previous metallic mitral and aortic valves replacements. Her medications included hydralazine, warfarin, insulin glargine, ergocalciferol, atorvastatin, isosorbide mononitrate, amlodipine, levothyroxine, minoxidil, clonidine, ferrous sulfate, montelukast, esomeprazole, and Colace (docusate). Physical exam was unremarkable. Specifically no skin rash or bruises were noted. Hemoglobin was 7.4 g/dl with a hematocrit of 21.9%. Iron was 13 mcg/dl, transferrin 87 mg/dl, iron saturation 12%, and ferritin 624 ng/ml. She had a recent unremarkable colonoscopy. Upper endoscopy was performed with no signs of active or recent bleeding. Blackish mucosa with intact villi was seen in the duodenal bulb and the second part of duodenum. Duodenal biopsies showed intact duodenal mucosa with slender villi and normal crypt to villous ratio. In the lamina propria, a black crystalline pigment was identified. There was no tissue reaction to this pigment with iron stain was negative and control adequate. Etiology of this pigment was deemed unknown. Discussion: While the clinical significance of pigment deposits in the duodenum is not known, observations suggest an association with chronic illnesses or the use of antihypertensive medications. Such association and the composition of those pigments are worth further exploration.