Choristoma

CHORISTOMA, choristia, choristoblastoma (from Greek choristo- meaning I separate). Choristia (chorista) - a term introduced by E. Albrecht in 1904 to denote a developmental anomaly of tissues consisting of the detachment, separation of certain parts of tissues and their inclusion in adjacent tissues; for example, additional pancreatic glands in the wall of the stomach and intestines, birthmarks having as their basis the separation of epithelial islets and their inclusion in the underlying connective tissue, the presence of areas of adrenal cortex under the kidney capsule. If choristia takes the form of a tumor, it is called a choristoma; this includes, for example, dermoid cysts that have developed from separated parts of the skin epithelium, chondromas of the lungs from separated bronchial cartilages, as well as various cysts and tumor-like formations that develop from separated parts of various embryonic clefts and ducts; e.g., branchiogenic cysts, tumors from Müllerian ducts of the uterus, from Wolffian-Gartnerian ducts, etc. (see Heteroplasia, Heterotopia). If a true tumor develops from choristia or choristoma, e.g., cancer, it is designated as a choristoblastoma.