S1318 Pseudomelanosis of the Small Bowel: A Systematic Review

Abstract

INTRODUCTION: Pseudomelanosis duodeni is identified by a tigroid mucosa with brown-black or grey-black speckling. It is not associated with laxatives, unlike its colonic variant. Over the years, isolated reports of pseudomelanosis across the duodenum, jejunum, and ileum have been reported that were not captured in previous reviews. We aim to summarize all affected cases and provide clinical characteristics of this visually striking disease. METHODS: We conducted a systematic review to identify all published reports of pseudomelanosis in the small bowel. A search string ("pseudomelanosis duodeni") OR ("duodenal melanosis") OR ("melanosis duodeni") OR ("melanosis ilei") OR ("pseudomelanosis ilei") OR ("melanosis intestini") OR ("pseudomelanosis intestini") OR ("melanosis jejuni") OR ("pseudomelanosis jejuni") was applied across databases (Figure 1). All cases were analyzed for characteristics with outcomes. RESULTS: 134 patients were identified. 82% of cases were identified by an EGD, while 5% used capsule endoscopy. Commonly affected segments were duodenum (70%), ileum (11%), stomach (7%), jejunum (5%), while 7% appeared endoscopically unaffected. Histology revealed a lack of fibrosis or cellular injury, reacting to prussian blue (43%), Fontana-Masson (27%), and PAS (16%) stains. Iron accumulations were frequently noted in samples (34%). The mean age was 61.23 ± 17 years, with 56% males. The most common coexisting comorbidities were HTN (63%), CKD (55%) with 13% on hemodialysis, iron deficiency anemia (23%), diabetes mellitus (22%), and heart failure (6%). Hiatal hernias were seen in less than 10% of cases. Anti-hypertensives (44%), iron supplements (41%), diuretics (31%), beta-blockers (26%), and multivitamins (12%) were most commonly implicated. Anti-reflux therapy was used in less than 5% of patients, while mortality was seen in 5% of all cases, mainly to renal failure (42%) and sepsis (14%). CONCLUSION: Pseudomelanosis of the upper GI tract maintains a distinct pathophysiology. The majority are diagnosed on endoscopy, and tissue diagnosis can be reassuring to the patient. There seems to be a firm association with chronic illness, that may contribute to impaired iron utilization. It is possible that defects in absorption can affect nutrients as well, contributing to GI symptoms of dyspepsia and abdominal discomfort, although the majority remain asymptomatic. Most cases resolve spontaneously, although the persistence of deposits is an emerging feature of this disease.Figure 1.: PRISMA diagram for pseudomelanosis of the small bowel.