Choristoma

Choristomas, a form of heterotopia, are masses of normal tissues found in abnormal locations.^[1][2][3][4] In contrast to a neoplasm or tumor, the growth of a choristoma is normally regulated.^[5]

It is different from a hamartoma. The two can be differentiated as follows: a hamartoma is disorganized overgrowth of tissues in their normal location (e.g., Peutz–Jeghers polyps), while a choristoma is normal tissue growth in an abnormal location (e.g., osseous choristoma,^[6] gastric tissue located in distal ileum in Meckel diverticulum).