A mass composed of histologically normal tissue found in an abnormal anatomic location (e.g., pancreatic tissue cells found in the liver, or smooth muscle proliferating along the facial nerve) is called a:

A choristoma is normal tissue in an abnormal location. A hamartoma, by contrast, is a disorganized overgrowth of tissue that IS normally found at that site. A teratoma contains tissue from multiple germ layers (often within a cyst), and a neoplasm is an abnormal, uncontrolled proliferation of cells (which may or may not be normal-appearing).