RESUMO

Heterotopic gastrointestinal cysts of the oral cavity are benign lesions usually discovered during infancy. Their pathogenesis is not very clear. They are rare congenital anomalies that result from remnants of foregut-derived epithelium in the head, neck, thorax or abdomen during embryonic development. The majority of these lesions occur in the anterior ventral surface of the tongue and extend to the floor of the mouth. They are confused clinically by surgeons in cases of head and neck masses in children as ranulas, dermoid and thyroglossal cysts, and lymphangioma. We report the case of a 28-day newborn with a 3.6 cm oval mass on the floor of the mouth causing difficulty eating and cyanosis during crying. Complete surgical excision was performed by an oral approach under general anesthesia. Microscopic examination revealed gastric epithelium with tall columnar mucous cells on the surface and numerous short closed crypts, resembling fundal glands and mature gastric epithelium.