melanoma in situ

Definition of melanoma in situ

melanoma in situ

(MEH-luh-NOH-muh in SY-too)
Abnormal melanocytes (cells that make melanin, the pigment that gives skin its natural color) are found in the epidermis (outer layer of the skin). These abnormal melanocytes may become cancer and spread into nearby normal tissue. Also called stage 0 melanoma.

Source: NCI Dictionary of Cancer Terms