Iron pill-induced duodenitis: A distinct pattern of duodenal mucosal injury in a patient with a duodenal mass.

Ferrous sulfate is an oral iron supplement commonly used to treat iron deficiency anemia. Upper gastrointestinal (GI) tract mucosal damage with associated tissue iron accumulation can sometimes occur with therapeutic dosages of oral iron-containing medications. A distinct histologic pattern of iron deposition with associated inflammatory and reactive changes caused by mucosal injury from oral iron-containing medications has been most commonly described within gastric biopsies and has been referred to as "iron-pill gastritis". There have only been very rare reports of duodenal mucosa biopsies demonstrating predominantly extracellular crystalline iron deposits with surrounding tissue inflammation and injury analogous to the "iron-pill gastritis" pattern. Here we report a case of "iron pill-induced duodenitis", an uncommon histologic pattern of duodenal iron deposition and mucosal injury seen in a female in her 50 s with clinical findings of a duodenal mass.