The vast majority of kidney cysts are asymptomatic and do not have a significant impact on human health. However, about 3% to 7% of kidney cysts may turn into kidney cancer, which requires timely detection and aggressive treatment.
The more reliable methods for diagnosing kidney cysts are ultrasound, x-ray imaging, radionuclide scanning, CT (computed tomography), and MRI (magnetic resonance imaging). Clinicians can grade renal cysts for malignancy using ultrasound and CT, a grading system known as the Bosniak grading system.
- Grade I cysts: simple benign cysts with thin walls, no separation or calcification, and watery fluid;
- Grade II cysts: benign cysts with small separations and or calcified spots, with no enhancement of the separations;
- Grade III cysts: thick walls, multiple intracapsular compartments and calcifications, with enhancement of the compartments, more than 50% malignant cysts;
- Grade IV cysts: malignant cysts with an enhancing soft tissue component within the cyst.
Therefore, for grade I-II cysts, observation follow-up is an option, whereas grade III-IV cysts should be surgically explored and removed as soon as possible.