Pseudomelanosis duodeni: a short review

Pseudomelanosis duodeni is characterized by the presence of brownish or blackish pigmentation in the duodenal mucosa identified during endoscopy. Although the pathogenesis is uncertain, it was generally believed that it is sequelae of luminal absorption of iron and sulfide chemicals, which is subsequently deposited in the lamina propria. It is often associated with hemodialysis and oral intake of iron supplements. Histologically it is characterized by dark brown pigmentation accumulated within macrophages in the lamina propria, particularly at the tips of villi. Histological differential diagnosis includes hemosiderosis/hemochromatosis, brown bowel syndrome and malignant melanoma, which could be differentiated using special stains and immunohistochemical markers. Pseudomelanosis duodeni per se does not lead to any clinical symptom; however, it indeed evokes anxiety and confusion for clinicians and pathologists because of its rarity, peculiar endoscopic features, and concerns for malignancy.