A neoplasm is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed.[3][4][5] This abnormal growth usually forms a mass, which may be called a tumour or tumor.[6]

Reference
Wiki: Skin tumor