[Renal lobar dysmorphism: dynamic CT or helical CT diagnosis].

Renal lobar dysmorphism (RLD), a developmental malposition of a renal lobe, contains both cortical and pyramidal structures. Of our ten cases, two were found as peripelvic masses on US, and one on MRI and angiography. The others were found incidentally within an eight-month period on abdominal helical CT performed for the detection of other diseases. These ten cases were correctly diagnosed on dynamic CT or helical CT because they clearly showed the typical cortical and pyramidal structures of RLD. In the corticomedullary phase of CT, the oval-shaped cortex of the RLD was demonstrated in the perihilar medulla of the kidney. The nephrographic phase revealed accumulation of contrast medium within the pyramid of the RLD. The so-called "junctional parenchyma" which was discussed recently was not confirmed in our cases. RLD has no pathological significance. To avoid unnecessary additional examinations or surgical intervention, it is important to recognize the entity of RLD and its correct diagnosis by dynamic or helical CT.