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Spontaneously thrombosed polar renal artery aneurysm: multidetector computed tomography findings.

CLINICAL PRESENTATION A 64-year-old white man had high blood pressure for 10 years which was controlled with medication. He presented with right upper quadrant pain and underwent ultrasound imaging, which revealed a solid exophytic lesion in the upper pole of the right kidney. Multidetector computed tomography (MDCT) was planned to exclude renal cell cancer. MDCT demonstrated an exophytic lesion that had rim calcification in noncontrast images (Figure 1). The lesion demonstrated no enhancement after administration of contrast material but was associated with a vascular structure. The main renal artery produced a branch (polar artery) near the hilum and the polar renal artery demonstrated a thrombosed aneurysm. The polar renal artery was larger than the main renal artery in addition to showing irregularity in contour (Figure 2). A renal artery aneurysm (RAA) is a rare abnormality with an incidence of less than 1% (ranging from 0.01% to 1%) and it is usually single and unilateral. RAA is asymptomatic and is found incidentally by diagnostic imaging. To the best of our knowledge, spontaneous thrombosis of a polar RAA has not been previously reported. As in our case, a thrombosed RAA may be misdiagnosed as a solid lesion such as renal cell cancer, and MDCT by dynamic examination demonstrates the vascular origin of the lesion. REFERENCES