Retroperitoneal mass and hydronephrosis

Abstract

T 49-year-old man presented to the hospital with a 3-day history of left flank pain. His past urologic history is significant for several bouts of gross hematuria after participating in long-distance running. On physical examination, the patient was normotensive. There was mild costovertebral angle tenderness. The urinalysis showed trace blood. A film of the kidney, ureter, and bladder (KUB) showed a 9 3 9-cm calcific mass inferior to the left kidney margin (Fig. 1). A computed tomography scan of the abdomen demonstrated left hydronephrosis with an obstructing stone in the proximal left ureter. There was a complex left retroperitoneal mass corresponding to the large rim calcification seen on the KUB film (Fig. 2). The patient underwent cystoscopy, a retrograde ureteropyelogram, and placement of a left JJ stent. A large proximal ureteral stone was now seen having been hidden within the outline of the calcified mass (Fig. 3). A magnetic resonance image of the abdomen further characterized this mass as separate from the kidney and arising from the retroperitoneum/psoas muscle (Fig. 4). The patient underwent extracorporeal shock wave lithotripsy using a Dornier HM4 unit (2000 shocks at 29 kV) with successful fragmentation of the stone. No intervention is planned at this time for the retroperitoneal mass as the patient was asymptomatic prior to the colic episode. It is believed that the mass was related to the blunt trauma sustained in a motor vehicle accident 18 years before this hospitalization. The differential diagnosis for this mass would include an old retroperitoneal hematoma or urinoma. The mass was only brought to our attention because of the acute renal obstruction. One can hypothesize that the mass may have impeded urinary drainage, resulting in stasis and subsequent stone formation.