Is there a contemporary role for percutaneous needle biopsy in the era of small renal masses?

Study Type – Diagnostic (case series) Level of Evidence 4 What's known on the subject? and What does the study add? The diagnosis of small renal masses (SRMs) has increased in recent years partly as a consequence of the liberal use of radiological imaging in an ageing co‐morbid population. Our knowledge of the natural history of SRMs now informs us of the indolent nature of most SRMs which parallels the expansion of management strategies for SRMs, including nephron sparing surgery, radiofrequency ablation, cryotherapy and active surveillance. Though conventional imaging has improved, imaging does not have the ability to characterise the biological or aggressive potential of an SRM. Renal mass biopsy (RMB) has increased in popularity in recent years and is a potential valuable tool in the assessment of SRMs. The facts that (1) a significant number of SRMs are diagnosed in an elderly patient cohort, (2) 20% of SRMs are benign on formal histology, (3) there are various management strategies now available and (4) modern RMB has a diagnostic accuracy >90% with few complications, are all reasons why there has been renewed interest in RMB. However, clinical judgement is paramount as there remains an unpredictable non‐negligible risk of disease progression and metastasis whilst on surveillance. OBJECTIVE•  To evaluate based on the best available data whether there is a contemporary role for percutaneous needle biopsy in the era of small renal masses.PATIENTS AND METHODS•  SRMs are acknowledged to be tumours less than 4 cm and account for 48%–66% of new kidney cancers. Renal mass biopsy (RMB), traditionally limited to specific clinical scenarios and with inherent diagnostic accuracy problems has increased in popularity in recent years and is a potential valuable tool in the assessment of SRMs. Our discussion focusses on these issues. •  We performed a thorough Medline literature review using a combination of the following keywords; small renal mass, renal biopsy, percutaneuous renal biopsy, renal mass biopsy and renal cell carcinoma. We identified the seminal articles with data/information pertaining to renal mass biopsy in small renal masses.RESULTS•  The facts that 1) a significant number of SRMs are diagnosed in an elderly patient cohort, 2) 20% of SRMs are benign on formal histology, 3) there are various management strategies now available and 4) modern RMB has a diagnostic accuracy >90% with few complications, are all reasons why there has been renewed interest in RMB.CONCLUSION•  There is a contemporary role for RMB in the era of SRM as the incorporation of molecular profiling of tissue from RMB would augment our ability to risk stratify SRMs on an individual patient basis and adopt management accordingly. However, clinical judgement is paramount as there remains an unpredictable non‐negligible risk of disease progression and metastasis whilst on surveillance.