Epipalatus: a rare intraoral teratoma.

A wide range of discrete head and neck tumors are developmental, including those termed choristoma, hamartoma, dermoid cysts, teratoid tumors, and true teratomas. In classifying various teratomas, consideration is given to the embryonal layers represented within the substance of the tumor and to their level of organizational complexity. By definition, a hamartoma is a tissue mass, present at or near the time of birth, that is benign and native to the site of origin. Growth capacity of a hamartomatous process parallels that of the host organism. A choristoma, on the other hand, is a mass of tissue that is foreign to the site of discovery and is thought to result from growth to displaced primordial tissue that is histologically normal for that tissue.