[Rupture of renal artery aneurysm into the renal pelvis].

We report a case of ruptured renal artery aneurysm into the renal pelvis. A 48-year-old woman presented with complaints of gross hematuria and right back pain. Abdominal ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) revealed the aneurysm, which was 5 x 5 cm in diameter. Enhansed CT revealed blood flow from the renal artery aneurysm into the renal pelvis. Radical nephrectomy was performed. Rupture of renal artery aneurysm into the renal pelvis is the 3rd case in the Japanese literatures. Pathogenesis and management of this rare condition are discussed.