Overgrowth of a skin structure at a localised region -

Hamaoma is a mass of disorganized tissue indigenous to the paicular site. A polyp is a mass that projects above a mucosal surface, as in the gut, to form a macroscopically visible structure. Choristoma is a congenital anomaly consisting of a heterotopic rest of cells. For example, a small nodule of well-developed and normally organized pancreatic tissue may be found in the submucosa of the stomach, duodenum, or small intestine. (Robbins Basic Pathology, 9 th edition. page : 162,163)