Black pigmentation in duodenum

Abstract

Here, we present the case of an 87-year-old woman with heart failure, hypertension, and iron deficiency anemia with a treatment history of amlodipine, olmesartan, carvedilol, and hydralazine for 4 years, and ferrous sodium citrate for 2 years. The patient was referred to the Department of Gastroenterology for occult blood in stool, and endoscopic examination was arranged. Colonoscopy showed sigmoid colon adenocarcinoma, and esophagogastroduodenoscopy revealed speckled black pigmentation distributed from the duodenal bulb to the duodenal second portion (Figure 1). Histopathology revealed macrophages in the lamina propria containing pigmented granules negative for Prussian blue stain (Figure 2). The final diagnosis was pseudomelanosis duodeni.

Pseudomelanosis duodeni, characterized by brown to black spotty pigmentation in the duodenal bulb and the second portion on esophagogastroduodenoscopy,^1-3 was first described in 1976 by Bisordi and Kleinman.⁴ It occurs more commonly in older women.³ The pathogenesis is distinct from melanosis coli and remains poorly understood.¹ Previous studies have shown association with diabetes mellitus, hypertension, renal disease, folate deficiency, gastrointestinal bleeding, and ingestion of food or oral agents containing iron and sulfur.^1-3 Thus, one hypothesis implicates the accumulation of iron and sulfur in the duodenal mucosa caused by drugs (eg, hydralazine, furosemide, and hydrochlorothiazide) and food absorption, microhemorrhages, or reduced sulfur clearance due to decreased renal function.¹ Usually, this is an incidental finding without obvious clinical symptoms. Microscopically, the pigmented granules are found in the macrophages located in the lamina propria.^{1, 3} Although all pseudomelanosis duodeni contains an iron component, Prussian blue stain can still sometimes be negative, possibly because the iron pigments are in a sulfide form, and do not react with Prussian blue staining reagents.⁵ Pseudomelanosis duodeni should be distinguished from metastatic malignant melanoma as it is a benign condition with no evidence of malignant transformation in the future.^1-3 Further investigation or management are not required.

All authors contribute to all stages of article composition: data acquisition and editing, manuscript drafting, and manuscript revision.

The authors declare no conflict of interest.

The patient authorized the publication of the data and the patient's anonymity is preserved in the article.