or hypernephroma Malignant tumour of the cells that cover and line the kidney. It usually affects persons over age 50 who have vascular disorders of the kidneys. It seldom causes pain, unless it is advanced. It may metastasize to other organs (e.g., lungs, liver, brain, bone) and go unrecognized until these secondary tumours cause symptoms. Blood can appear in the urine early on but is painless and usually disregarded. Even when the cancer is in the early stages, X-ray films can show deformity in kidney structures