Pseudomelanosis Duodeni: A Unique Finding from an Upper Gastrointestinal Endoscopy

Abstract

Purpose: Pseudomelanosis duodeni is a rare, benign condition characterized by dark spots in the duodenal mucosa considered to be a collection of pigment- laden macrophages in the tip of the duodenal villi. There are very few case reports to date describing this condition. In this case report we describe classical endoscopic and histological findings of this rare condition and review the existing literature. Case Report: An 80-year-old black woman with history of mitral valve disease, heart failure, chronic kidney disease (not on dialysis), hypertension, hypothyroidism and diabetes mellitus, was referred for a gastrointestinal endoscopy to work up her anemia. She had required multiple transfusions in the past for anemia and was also on oral iron medication. Upper endoscopy revealed multiple AVMs that were successfully cauterized by argon plasma coagulation. Also noted were patchy abnormal dark pigmentation in the stomach mucosa and diffuse dark pigmentation of entire examined small bowel. Biopsies of the duodenum revealed accumulation of abnormal dark pigment within the macrophages of the lamina propria, which was negative for iron stain. A diagnosis of pseudomelanosis duodeni was made based on the endoscopic and histological findings. Discussion: Pseudomelanosis Duodeni is a rare, benign condition of unknown etiology. This condition was first described by Bisordi and Kleinman in 1976, and since then there have been few cases reported to date. To an endoscopist, it typically appears as a flat, discrete, brown or black speckled appearance of the duodenal mucosa. On histology, the duodenal biopsy shows aggregation of black granular pigment in the macrophages within the tips of the mucosa and do not typically stain for iron. Based on review of literature it occurs mostly in adults (92%) and has a more female predominance (12:1). There is a strong association between this condition with other chronic diseases including hypertension, diabetes and chronic kidney disease and all of these were noted in our patient. The pathogenesis of this condition is not known, and the source of pigment and the mechanism by which this pigmentation occurs is yet be delineated. It has been suggested by using electron probe analysis that coupling of iron with sulfur in pseudomelanosis duodeni affects iron transport and results in accumulation of iron sulfide in macrophages. Unlike in the other organs of the body the deposition of iron does not cause fibrosis and the course of the disease appears more benign. The diagnostic and prognostic significance of Pseudomelanosis duodeni has yet to be determined and guidelines for endoscopic surveillance have yet to be determined.