A case of foregut cyst communicated with esophagus and lined by bronchial mucosa is reviewed and its embryologic base of maldevelopment is discussed. It is not always easy to distinguish between digestive and respiratory cyst in mediastinum. There is whole range of intermediate between a cyst with ciliated and one with squamous or columnar mucosa. Origin of this dysembryoplasia is difficult to determine when one consider that the esophagus is covered with ciliated epithelium until the eleventh week of fetal life and that ciliated growth are found on its wall until the sixth month of the fetal life. And we concluded, general agreement is that cysts which have gastric epithelium in whole or in part, represent a distinct type and should be classified as (gastro) enteric cyst, mediastinal cyst containing cartilage were considered definitely as respiratory(bronchial or bronchogenic) cyst.