Neoplasia is the scientific term for the group of diseases commonly known as tumours (tumors) or cancer, although neoplasms can be benign, like a nevus (or 'mole'). Neoplasia is defined by an abnormal proliferation of cells in the body, the result of which is called a neoplasm.
According to the British oncologist R.A. Willis, "A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues, and persists in the same excessive manner after cessation of the stimulus which evoked the change."
A neoplasm can be benign, a potentially malignant 'pre-cancer', or a malignant cancer.[1][2]