I am a potential kidney donor and upon having a CT with contrast to clear me as a donor they found a 1.4cm renal cyst on my left kidney that they were not concerned about. On my right kidney they found a 1.9x2.1cm indeterminate renal cortical lesion with slight internal septation and borderline enhancement. They are sending me for an MRI on Monday but I'm very concerned that this is likely to be cancer. Can you give me some insight into how often a cyst with these features I described (borderline enhancement and thin septation) are benign vs malignant? I'm afraid and would like the insight of someone who sees this regularly.