Pseudomelanosis Duodeni in Post Renal Transplant Patient

Abstract

Purpose: Pseudomelanosis duodeni is a dark, speckled appearance of the duodenal mucosa on endoscopy, similar to melanosis coli. It is thought to be associated with hypertension, chronic renal failure, gastrointestinal bleeding, iron therapy, chronic heart failure and diabetes mellitus. Case: A 54-year-old female with a past medical history significant for diabetes mellitus type 2, end stage renal disease status post kidney transplant in 2006, hypertension, anemia of chronic disease and hypothyroidism presented with a one month history of nausea, vomiting and diarrhea. The diarrhea was five-six times a day, watery and nonbloody. Initial work up including stool culture, ova and parasite, stool WBC and C. difficile toxin were all negative. An upper gastrointestinal endoscopy performed for her symptoms of nausea, vomiting, and diarrhea showed pigmented dark lesions in the duodenal mucosa (Figure 1). Duodenal biopsies revealed pigmented macrophages in the lamina propia. Staining of the specimen with Masson Fontana stain was positive and consistent with melanosis. Periodic acid-Schiff stain and iron stains were negative. Colonoscopy done two days later was macroscopically normal. Random biopsies taken throughout the colon showed benign colonic mucosa with no signs of active inflammation. Discussion: Pseudomelanosis duodeni is a rare entity that is described as dark pigmented granules seen inside the macrophages that lie within the lamina propia of the duodenal villi. The pathogenesis of pseudomelanosis duodeni is not entirely clear. It was first described in 1976 by Bisordi and Kleinman and was initially thought to be a form of stored iron resulting from oral iron supplementation. It appears to be more common in females in the sixth to seventh decade of life and has also been seen in patients with hypertension, chronic renal failure, congestive heart failure and diabetes mellitus. No follow-up protocol or specific treatment is required at this time. The clinical significance of this entity still remains unclear but may pose a diagnostic challenge at endoscopy.Figure: [1378] Figure 1. Duodenal bulb melanosis.