INTRODUCTION: Duodenal pseudomelanosis (DP) is a relatively rare condition discovered incidentally during esophagogastroduodenoscopy (EGD) and characterized by pigment−laden macrophages within duodenal villi. A strong association has been described with chronic renal failure, hypertension, diabetes mellitus, upper GI bleeding and certain medications. Though several case reports exist, there is only one other case report to our knowledge documenting this phenomenon in a postrenal transplant patient. CASE DESCRIPTION/METHODS: A 77-year-old female with a medical history of diabetes mellitus, chronic kidney disease post renal transplant, gastroesophageal reflux disease and coronary artery disease presented with chronic, intractable, epigastric pain associated with sitophobia and weight loss. The pain was worsened by food and no longer responsive to proton pump inhibitor therapy (PPI) and sucralfate. There was minimal epigastric tenderness on abdominal exam. EGD showed mild, chronic gastritis and boggy, edematous, dusky small intestinal mucosa with punctate erythema. She was empirically started on intravenous PPI BID and Carafate QID as well as hospitalized due to concern for mesenteric ischemia. However, MRA of the abdomen showed patent mesenteric arteries thus repeat EGD was performed to obtain biopsies. It revealed a melanosis appearance of the bulb and second portion of the duodenum (Figures 1 and 2). Biopsy pathology showed benign mucosa with DP (Figure 3) and H. pylori-negative mild chronic gastritis of the gastric antrum. DISCUSSION: Unlike pseudomelanosis coli, DP does not have a known association with anthraquinone-containing laxatives. It is hypothesized that the coupling of iron and sulfur impairs iron transport and results in pigment accumulation. The proximal duodenum is the site of maximal iron absorption in normal physiology. Thus, iron supplementation and upper GI bleeding have been highly associated with DP. The sulfur component likely originates from sulfa-containing medications. However, other drugs containing cyclic compounds such as phenols, indoles and skatoles have also been described as causing pigment accumulation. Our patient was not taking any medications known to be associated with DP. Interestingly, DP has been documented to persist despite resolution of chronic kidney disease in a post renal transplant in one case report prior to our patient. With the addition of this case report to the literature, we continue to raise question of the involvement of renal impairment in DP.Figure 1.: EGD showing melanosis appearance of the duodenum.Figure 2.: EGD showing melanosis appearance of the duodenum.Figure 3.: H&E stains confirming benign duodenal pseudomelanosis.