Peter L Royce
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.
Joan, 64 years of age, has a past medical history of hypertension, rheumatic fever, appendicectomy and cholecystectomy. She presented to her general practitioner with difficulty in swallowing. Joan was otherwise well with no constitutional symptoms and no recent weight loss. She was suspected to have a foreign body lodged in her oesophagus.
Joan underwent an ultrasound which excluded a foreign body but detected an incidental finding of a right superior pole renal mass. A four phase computerised tomography scan was performed in order to further characterise the lesion. This showed a 25 mm enhancing lesion in the supero-posterior aspect of the right kidney (Figure 1). The contralateral kidney appeared normal. There was no renal vein tumour, thrombus or lymphadenopathy evident. Laboratory testing revealed renal impairment with a serum creatinine of 160 μmol/dL and an estimated glomerular filtration rate (eGFR) of 41.
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