Some of you will be nervous when you get the CT or MRI report and see that there are cysts in the kidney, but before you get nervous, please take a closer look at the report to see which category the cysts in the kidney belong to. The incidence of kidney cysts is very high, and since kidney cysts can be benign or malignant, how exactly can we determine their benignity and malignancy? In fact, it is difficult to evaluate the image accurately, so many imaging experts have created some classification methods, each type corresponds to a different chance of malignancy, and the one that is more accepted by most people is Bosniak classification: Class I, simple cysts with clear margins, no separation, no calcification, no solid components, no enhancement. Class II, may have slender separations, calcification, and may have enhancement, but cannot be accurately measured. High density cysts (uniform density without enhancement) less than 3 cm in diameter. Category III, IIF (“F” for follow up) – those that cannot be classified as II or III, with slight thickening of the partitions or cyst wall, including high density cysts greater than 75 px in diameter. Class IV, cysts with heterogeneous density, measurable enhancement, thick compartments (greater than or equal to 2 mm), visible nodules, and irregular calcifications (centrally located, greater than or equal to 2 mm). Category V, cystic kidney cancer. In our own experience, the likelihood of Class I and II is almost zero. Class III has a 75% chance of malignancy, while Class IV has almost 100% chance. IIF is difficult to classify and does not require surgery for the time being, but needs to be followed up and reviewed.