An MRI done on me last May 7 reveals the presence of 3 cortical systic foci in each kidney with the largest seen in the upper pole of the left kidney measuring 0.7 x 1 cm. I had a partial robotic nephrectomy on my left kidney early last year to remove a malignant tumor which measured 3cm x 2.3 cm. Does this mean that the cortical systic foci which were so small (sub-centimeter) on the MRI done 7 months prior to the May 7 MRI develop into a malignant tumor? Note that from sub-centimeter it grew to 0.7 x 1 cm in just 7 months.
Dear friend, welcome to Chat Doctor.  If you had a malignant tumor removed last year with partial neurectomy, it could very well be the same kind this time also due to microscopic spread. Was it in the same upper pole area last year?they need evaluation and close watch for malignancy again. Benign cysts are very common. But, in your case caution is necessary. Better consult your neurosurgeon in time.  I hope to have satisfied your query. Keep me posted. Good luck !!