Horseshoe kidney on FDG positron emission tomographic imaging is easily confused with malignancy
Tomography, X-Ray Computed
Conjoined or "horseshoe" kidneys are congenital anomalies that result from fusion of the independent metanephric blastemas during the second gestational month before their cephalad migration. It occurs once in every 400 births, for a prevalence of approximately 0.25% of the population. Positron emission tomography with fluorodeoxyglucose is an effective imaging technique for detecting and staging various neoplastic diseases. However, assessment of the kidneys can be confounded by accumulation of radioactivity in regions of urinary stasis. Capacious collecting systems and urinary stasis are common in horseshoe kidneys. This can make horseshoe kidneys challenging to recognize because of their atypical location and structure. This report documents a case that would have been confused with malignancy without correlation with anatomic images.