BACKGROUND:The jejunal mucosa is the major site involved in celiac disease, but modifications have also been found in the gastric, rectal and esophageal mucosa. Few studies have focused on the histomorphological features of the oral mucosa in celiac disease patients. Our objectives were: (i) to assess the presence, quality and intensity of lymphocytic infiltrate in clinically healthy oral mucosa and its relation to celiac disease severity (villous height to crypt depth ratio); and (ii) to detect any other histological features connected to celiac disease.METHODS:Twenty-one untreated celiac disease patients (age range 13-68 years) with clinically healthy oral mucosa were enrolled and compared with 14 controls. Intestinal and oral biopsies were carried out and specimens were evaluated after staining with hematoxylin and eosin.RESULTS:Intra-epithelial lymphocyte B and T infiltrates of the oral mucosa were found to be similar in both groups; likewise, intensity of the lymphocytic infiltrate in the lamina propria was similar in both groups and was not related to intestinal damage; important signs of spongiosis were found to be more significantly present in celiac disease patients compared with controls (P = 0.0002).CONCLUSIONS:Our study showed that the healthy oral mucosa of untreated patients does not reflect the intestinal damage by celiac disease, but it is unexpectedly affected by spongiosis, as being detected for the first time in the literature. This latter feature could be related to gliadin ingestion and could contribute to explain the higher susceptibility of celiac disease patients to suffering from oral mucosa lesions.