Kidney tumors can be divided into benign and malignant tumors, the vast majority of which are malignant and benign ones are rare.
Benign tumors of the kidney
Benign tumors in most cases have no health consequences and usually do not recur after treatment or surgical removal. The tumor does not invade surrounding tissues and does not metastasize to other organs.
The most common benign tumors of the kidney are pheochromocytomas and renal vascular smooth muscle lipomas (renal malignancies), in addition to papillary adenomas of the kidney, which are often found incidentally in surgically resected specimens because of their small size.
Malignant tumors of the kidney
Malignant tumors of the kidney account for the majority of renal tumors, have a significant impact on health, are prone to recurrence after resection, and often invade surrounding tissues and metastasize to other organs.
Renal cell carcinoma accounts for about 85% of all kidney malignancies, and we often refer to renal cell carcinoma when we say “kidney cancer”. The most common pathological type of renal cell carcinoma is clear cell carcinoma, followed by papillary renal cell carcinoma and suspicious cell carcinoma.
Another common type of malignancy is uroepithelial carcinoma of the renal pelvis (pelvic carcinoma), which is a group of malignant tumors that occur in the urinary outflow tract and can often be accompanied by or followed by the same pathologic type of tumor in the ureter and bladder (ureteral carcinoma, bladder carcinoma).
Another type of kidney tumor that occurs in children is called Wilm’s tumor, or nephroblastoma, and other types of kidney cancer are extremely rare in children.