A tumour, or neoplasm, is a tissue growth with no physiological function. The first sign of tumour growth in a tissue is the appearance of a small number of cells which multiply with uncontrolled division and lose lose their capacity for differentiation. The tumour enlarges solely as a result of multiplication of its own cells. Tumour growth proceeds through stages of disorderly increase in the number of cells, focal growth, benign growth and malignant growth; the stages immediately preceding malignancy are called precancerous.