The frequency of histological features mimicking reflux esophagitis: a study in non-human primates

The frequency of histological changes mimicking those described for reflux esophagitis in humans was assessed in a cohort of non-human primates (NHP).

A total of 121 consecutive esophagi (from 103 baboons and 18 macaques) were classified according to Ismail-Beiji for reflux esophagitis in humans into grade 1, grade 2 and grade 3 esophagitis.

Histological features compatible with reflux esophagitis were found in 28.2% of the baboons and in 22.2% of the macaques. Esophagitis grade 1 was more common in baboons (24%) than in macaques (6%), while esophagitis grade 2 was more common in macaques (17%) than in baboons (2%).

Although the prevalence of reflux esophagitis in man is at least 2%, only a fraction of patients demonstrate histological features consistent with grades 1, 2 or 3 esophagitis. Hence, the finding that 27% of a cohort of consecutive, unselected NHP had grades 1, 2 or 3 esophagitis at histology is remarkable. The possible causes for the difference between species, such as the oblique position often adopted by NHP during the gastric phase of digestion, the diet, regurgitation and subsequent re-ingestion, as well as the stress of NHP when kept in captivity, are reviewed.