Kidney Mass Found on CT or MRI: What Should You Do?
Understanding an incidental finding and the tests that follow
Quick answer
A kidney mass discovered incidentally on CT or MRI is a legitimate source of concern, but it is not always a cancer: many masses are benign (cysts, angiomyolipomas). A further work-up clarifies the nature of the lesion and the course of action.
An increasingly common finding
With the widespread use of CT and MRI, more and more kidney masses are discovered incidentally, during an examination performed for an entirely different reason. This finding is a legitimate source of concern, but not all kidney masses are cancers.
Is a kidney mass always a cancer?
No. Many kidney masses are benign: simple cysts (very common and harmless), angiomyolipomas, or other benign lesions. However, some solid masses require further tests to rule out a malignant tumour (renal cell carcinoma).
Which further tests are performed?
The work-up generally relies on CT or MRI with contrast injection, which allows the mass to be characterised. Depending on the results, a percutaneous biopsy may be offered to confirm the nature of the lesion before any treatment decision.
What happens if a tumour is confirmed?
If a kidney tumour is confirmed, management is discussed at a multidisciplinary team (MDT) meeting. Depending on size and location, several minimally invasive options exist, including percutaneous cryoablation and radiofrequency ablation.
Frequently asked questions
Is a kidney cyst dangerous?
Does every suspicious kidney mass need to be operated on?
How quickly can I get a specialist opinion?
Diagnosis, cryoablation, radiofrequency, follow-up: everything about the management of kidney tumours.
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Why this page is trustworthy
Written by the Interventional Radiology team at Cochin Hospital AP-HP, Université Paris Cité. Medically reviewed by an interventional radiologist of the department. Last updated: August 2026.