Simple renal cysts are extremely common, and the incidence increases with age. Approximately 25% of people who are 40 years or older and approximately 50% of people who are 50 years or older have simple kidney cysts. Solitary renal cysts are usually incidentally discovered and are typically asymptomatic.
The Bosniak classification system of renal cystic masses divides renal cysts into 5 categories based on imaging characteristics (e.g., septations, calcifications, nodularity, and enhancement) on contrast-enhanced CT, although recent updates have proposed incorporating other modalities such as MRI:
Bosniak 1: Simple: No follow-up necessary
Bosniak 2: Minimally complex: No follow-up necessary
Bosniak 2F: Minimally complex: Recommend follow-up with CT and/or MRI
Bosniak 3: Indeterminate: Recommend surgery (biopsy controversial)
Bosniak 4: Malignant: Recommend surgery
You do not need to follow your 5 mm cyst in your lower right kidney. If no comment is made about its complexity, it is likely simple or too small to characterize.
Hello~First, when did you see the records, how long ago was the scan? If it was a while back, then I wouldn't worry about it, the ordering physician would certainly let you know if you needed to take any more tests, etc to rule out anything serious. That being said, even if they test was just done, if the doctor hasn't said anything, then I wouldn't worry about it.
If it makes you feel better, then check with the doctor, but as I said, I doubt if you have a thing to worry about, the doctor would have told you so otherwise.