Fig. 4

a 77-year-old man, presented in 2007 with a 3 cm diameter lower polar enhancing soft tissue mass as shown in this delayed phase of a contrast-enhanced CT study, for which RFA was done. b Same patient during the session, air bubbles are seen around the probe, reflecting successful delivery of the waves and tissue necrosis. c Same patient. Contrast-enhanced CT; coticomedullary phase at 1-month follow-up reveals the density of the mass is heterogeneous with areas of fat and non-enhancing tissue strands. d Follow-up was continued yearly onwards, this is a contrast-enhanced CT image from the 4-year follow-up reveals the decreasing size of the lesion, also noted are fine dystrophic calcifications around the fibrous capsule. The kidney shows hydronephrotic changes, with thin parenchyma and dilated kinked ureter down to the level of the mass, thought to be secondary to entangling of the ureter within the focal fibrotic process of the lesion, for which the patient refused further management. e Same patient, contrast-enhanced CT study at nephrographic phase at 13-year follow-up reveals the increase in dystrophic calcifications inside the lesion with absence of measurable enhancement