The appearance of the lesion helps a doctor differentiate between kidney cysts and cancer from an ultrasound picture, according to the Kidney Cancer Institute. A simple kidney cyst has no chance of being malignant, while a complex kidney cyst is potentially cancerous.
A simple kidney cyst is a spherical space within the kidney filled with yellow or clear fluid, explains the Kidney Cancer Institute. In some cases, the cyst contains blood. The walls of the cyst are thin with no irregularities. As people age, it is not unusual for simple kidney cysts to develop. Doctors often discover them accidentally when performing diagnostic tests for other issues. Simple cysts are not a cause for concern and are not cancerous.
A complex kidney cyst has irregular walls or contents, states the Kidney Cancer Institute. The walls may be fine and thin or thick and coarse. A complex cyst with multiple thick walls suggests the presence of cancer. If a contrast agent used during the imaging test "enhances," this indicates that a blood supply is present in the cyst, and it is likely to harbor cancer.
The Bosniak classification provides a way for doctors to classify cysts and determine the risk that they are cancerous, notes the Kidney Cancer Institute. Using this classification, doctors can create a plan to treat the cyst. Observation with periodic follow-up imaging is a possible approach, states CNN. Absence of change indicates a benign cyst, while progression suggests malignancy, in which case the doctor may conduct a biopsy or remove the kidney.