Renal artery aneurysm causing hydronephrosis.

A 42-year-old man presented with left hydronephrosis incidentally discovered on abdominal echogram during a routine health examination. Color Doppler ultrasonography, intravenous pyelography and angiography revealed a non-calcified renal artery aneurysm of 30 mm in size compressing the pyeroureteral junction and causing hydronephrosis. Three-dimensional computed tomography (3-D CT) using spiral CT clearly displayed the aneurysm located at the first bifurcation of the left renal artery and involving the anterior segmental artery. Decompression was successfully obtained via in situ revascularization of the renal artery after aneurysmectomy. A literature search revealed 12 cases of renal artery aneurysm causing hydronephrosis reported in Japan, although only three cases were documented in other countries, and these reports are reviewed. Use of 3-D CT for evaluation of renal artery aneurysm is advocated.