[Pseudomelanosis duodeni:a case report].

An 83-year-old Japanese man underwent esophagogastroduodenoscopy for screening purposes. He had a medical history of hypertension, chronic kidney disease, chronic heart failure, and chronic myeloid leukemia, and he had been taking the following medications:ferrous citrate, furosemide, spironolactone, tolvaptan, bisoprolol, nicorandil, warfarin, nilotinib, febuxostat, esomeprazole, digestive enzyme complex, ambroxol, carbocysteine, and potassium L-aspartate. Esophagogastroduodenoscopy revealed a brownish speckled pigmentation in the duodenal bulb. Biopsy specimens from the duodenal villi revealed a brown pigment deposition, which appeared bright on scanning electron microscopy. Energy dispersive X-ray spectroscopy and elemental mapping revealed the presence of iron and sulfur in the duodenal villi. Consequently, pseudomelanosis duodeni was diagnosed based on these findings.