Pseudomelanosis of the Upper GI Tract: A Rare Endoscopic Finding

Abstract

Pseudomelanosis is a rare, incidental finding in the upper gastrointestinal tract. It is characterized by dark, pigmented inclusions in the histiocytes of the lamina propria. The exact etiology is unknown, but it has been associated with medical conditions like chronic renal disease, hypertension, and diabetes mellitus as well as the use of various medications, including hydralazine and iron supplements. We present two cases with this uncommon endoscopic finding. The first case is a 51 year old male with prior medical history of iron deficiency anemia with use of iron supplementation in the past, chronic kidney disease stage 4, and hypertension who presented with anemia. His medications included hydralazine. EGD was performed which revealed purplish discoloration of the gastric mucosa. Pathology showed gastric mucosa with mild foveolar hyperplasia and lamina propria histiocytes containing melanin-like pigment, consistent with pseudomelanosis. Prussian blue stain was positive for iron. The second case is of a 80 year old female with ESRD on hemodialysis and hypertension who was evaluated for iron deficiency anemia. Her medication list included hydralazine and ferrous sulfate. EGD was performed which revealed abnormal dark pigmentation of the distal antrum and duodenum. Biopsies of both areas revealed groups of histiocytes containing granular black pigment at the tips of the duodenal villi and in the superficial gastric antral mucosa. Prussian blue stain was positive for iron. Pseudomelanosis in the stomach and duodenum is a rare endoscopic finding. Duodenal pseudomelanosis was first described by Bisordi and Kleinman in 1976 and gastric pseudomelanosis by Treeprasertuk et al. in 2000. Iron is the most common medication associated with this condition. The hyperpigmentation in pseudomelanosis is attributed to uptake of exogenous substances by macrophages and formation of pigmented deposits. The etiology of pseudomelanosis is not known, nor is there any reported association with malignancy or fibroproliferative disease. To our knowledge, the 51 year old patient described here is the youngest patient with gastric pseudomelanosis described in the literature.Figure: Dark pigmentation of duodenal mucosa.Figure: Discoloration of gastric mucosa.Figure: Prussian blue stain positive for iron.