Benign renal tumors: diagnosis and treatment

Renal tumors both benign and malignant have two basic growth patterns. One pattern is that of appositional growth in which a round mass is shown displacing the normal kidney. The other is that of infiltrative growth. In this situation, the tumor cells grow between the scaffolding of the normal glomerulae and tubules. Thus, in this situation, kidney function appears normal until late in the disease. The kidney thus keeps its reniform shape but does increase in size (bean or orange to grapefruit pattern).