Gastric and duodenal pseudomelanosis: a new insight into its pathogenesis

Tang_headshot Post written by Shou-jiang Tang, MD, from the Division of Digestive Diseases, Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA.

We report a case of gastric and duodenal pseudomelanosis; its full development was documented on serial upper endoscopies over 2 years, preceded by an 18-month daily iron supplement, interval development of iron pill-induced mucositis at the dependent portions of the stomach, and subsequent development of diffuse mucosal pseudomelanosis within the dependent portions of the stomach. Biopsies of the normal appearing stomach showed normal pathology without iron deposits, while the biopsy of the pigmented gastric mucosa showed iron deposits. We hypothesize that pill-induced mucosal injury exposes macrophages within the gastric mucosa to iron and other pigments. This generally occur at the dependent portions of the stomach such as the posterior wall when supine and the greater curvature when standing or sitting. The duodenum is the absorptive organ for iron and other pigments. The jejunum is usually spared due to the lack of absorption by its mucosa.

Very infrequently, gastric melanosis and pseudomelanosis have been described. Melanosis refers to melanin deposition, and pseudomelanosis is due to hemosiderin deposition. The etiology of these entities is poorly understood. Generally, it is very difficult to differentiate between melanosis and pseudomelanosis on endoscopy. Pseudomelanosis is more common in patients with hypertension, chronic renal failure, diabetes mellitus, history of upper gastrointestinal bleeding, and oral iron intake. Our video brought new insight into its pathogenesis: mucosal injury and absorption of hemosiderin.

Read the full article online.

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