BACKGROUND: Pseudomelanosis duodeni (PD) is a rare incidental endoscopic finding characterized by flat, discrete speckles of dark pigment, usually in the proximal duodenum. PD is associated with chronic conditions, including end-stage renal disease, hypertension, and diabetes, and with certain medications, including oral iron supplements and sulfur-containing antihypertensives.

CASE REPORT: A 56-year-old woman presented with lower abdominal pain, intermittent rectorragia, and a history of peptic ulcer disease and iron-deficiency anemia, treated with oral iron supplements. She was hemodynamically stable, and laboratory test results were pertinent only for microcytic anemia. In the workup of iron-deficiency anemia, esophagogastroduodenoscopy was performed, showing findings suspicious for PD, which was confirmed by pathology. Colonoscopy revealed large internal hemorrhoids, and hemorroidectomy was scheduled during the same admission. Duodenum biopsies showed edematous villosities and large clusters of pigmented macrophages, with golden-brown cytoplasm positively stained with Perl’s Prussian blue stain, indicating the presence of iron inside the macrophages. These findings confirmed the PD diagnosis. The pigment in PD is composed primarily of iron and sulfur, with iron being the main component, as seen in staining. In our case, we present findings of PD along with lower gastrointestinal bleeding manifesting as hemmoroidal bleeding. Giving the anatomical nature of hemorrhoids and that our patient was on oral iron therapy, the most likely mechanism behind the development of PD in our case was related to the oral iron therapy.

CONCLUSIONS: PD is a benign disorder of the duodenum. Further studies are needed to investigate its long-term outcomes and to formulate optimal management strategies.

Keywords: Melanosis, Pigmentation, Duodenum, Iron