Heterotopic gastrointestinal mucosa in the oral cavity of adults.

Heterotopic gastrointestinal mucosa (HGM) is a rare entity observed in the head and neck region and occurs more frequently in male infants and children. The floor of the mouth and anterior aspects of the tongue are the most commonly affected sites. Histologically, HGM resembles gastric, intestinal or colonic mucosa with areas of squamous epithelium, which can be cystic or solid. In the current report, 2 cases of HGM affecting the oral mucosa in patients over 35 years of age are presented, and one of these cases presented 2 nodules in different locations. Both cases represented solid lesions instead of the more common cystic presentation showing gastric glandular-type tissue that was lined with pseudostratified columnar epithelium containing crypts and fundic glands. Immunohistochemical analysis revealed positive expression of cytokeratins 7, 8 and 18 and smooth muscle actin (SMA). In both cases, the final diagnosis was HGM, and conservative surgical excision was performed.