Stanford University Medical Center Stanford, CA, United States
Justin Zhuo, MD1, Iny Jhun, MD1, Peter Beah, MD2, Rani Berry, MD3 1Stanford University Medical Center, Stanford, CA; 2Ronald Reagan UCLA Medical Center, Los Angeles, CA; 3Stanford University Medical Center, Palo Alto, CA
Introduction: Pseudomelanosis of the gastrointestinal tract is most commonly described in the colon and associated with anthraquinone-containing laxatives. Pseudomelanosis of the small bowel, however, is rarely encountered. Here, we describe a case of duodenal pseudomelanosis that was discovered incidentally during endoscopic evaluation for graft versus host disease (GvHD).
Case Description/Methods: A 55-year-old male with a history of hypertension, stage IV chronic kidney disease, aplastic anemia status post bone marrow transplant, GvHD, and iron overload from repeated blood transfusions presented with one week of fevers, cough, dyspnea, and diarrhea. His home medications included hydralazine, metoprolol, doxazosin, famciclovir, letermovir, atovaquone, posaconazole, prednisone, montelukast, and famotidine. He was started on intravenous antibiotics for multifocal pneumonia. Although stool gastrointestinal pathogen panel and Clostridioides difficile toxin PCR were negative, he was treated empirically with oral vancomycin due to his chronic immunosuppression. His cough and dyspnea improved, but his diarrhea was persistent; therefore, esophagogastroduodenoscopy (EGD) and flexible sigmoidoscopy were performed to rule out GvHD and CMV colitis. EGD revealed mild gastritis, several duodenal polyps, and diffuse melanotic pigmentation of the duodenal mucosa; flexible sigmoidoscopy was unremarkable. Histology demonstrated pigment granules within the lamina propria that did not react with iron or special melanin staining. Biopsies were negative for GvHD and CMV. These findings were consistent with duodenal pseudomelanosis. His symptoms resolved after several days, and he was discharged on oral levofloxacin and vancomycin.
Discussion: Pseudomelanosis duodeni is a rare condition characterized by speckled black pigmentation of the duodenal mucosa. Although the exact pathogenesis is unknown, it has been associated with common conditions such as hypertension, chronic kidney disease, diabetes mellitus, and various medications including iron supplements, hydralazine, beta blockers, and diuretics. The finding of pseudomelanosis itself is benign. However, its existence is important to recognize as the endoscopic differential diagnosis includes clinically significant conditions such as melanoma, brown bowel syndrome, and hemochromatosis. Increased awareness of this condition can prevent unnecessary additional diagnostic tests and interventions secondary to its rarity and distinct appearance on endoscopy.
Figure: Figure 1. Upper endoscopy demonstrates diffuse speckled dark pigmentation throughout the duodenal bulb (A). Histological examination of duodenal biopsies reveals pigment deposition within the lamina propria (B, hematoxylin and eosin stain) that stains negatively for iron (C, Prussian blue stain).
Disclosures:
Justin Zhuo indicated no relevant financial relationships.
Iny Jhun indicated no relevant financial relationships.
Peter Beah indicated no relevant financial relationships.
Rani Berry indicated no relevant financial relationships.
Justin Zhuo, MD1, Iny Jhun, MD1, Peter Beah, MD2, Rani Berry, MD3. P3025 - Pseudomelanosis Duodeni: A Rare and Incidental Endoscopic Finding, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.
