Incidentally detected small renal masses - investigation and management

With increasing use of imaging to diagnose other conditions, incidentally detected small renal masses and cysts are now a common clinical scenario for both the general practitioner and the urologist.

This article outlines a diagnostic and management approach to the incidental finding of a small renal mass or cyst.

Renal cell carcinoma represent 2-3% of all cancers and more than 50% of these are detected incidentally. Small renal masses are defined as renal masses less than 4 cm in diameter. They comprise a heterogeneous group of lesions; 20% are benign and only 20-25% prove to be potentially aggressive kidney cancers at the time of diagnosis. Work-up involves a full history, looking for evidence of paraneoplastic syndromes and examination, which is usually normal. Recommended blood tests include basic biochemistry and haematology, and imaging. A four phase contrasted computerised tomography scan of the kidneys allows a detailed examination of each aspect of the functional anatomy of the kidney, which can help approximate risk of malignancy and direct management. Not all patients with small renal masses require a biopsy. However, biopsy is required in patients who opt for active surveillance or ablative therapy. Management options include surveillance, surgery and ablative techniques.