Should a normal kidney be traversed to biopsy a renal cell carcinoma (RCC)?

From the Guidelines

Traversing normal kidney tissue to biopsy a renal cell carcinoma (RCC) should generally be avoided whenever possible. The preferred approach is to select a biopsy path that avoids normal renal parenchyma, instead accessing the tumor directly through the capsule or via an approach that minimizes passage through healthy kidney tissue. This recommendation stems from several important considerations, including the risk of tumor seeding along the needle tract, potentially spreading cancer cells to previously uninvolved areas, as well as the increased risk of bleeding complications due to the high vascularity of normal kidney tissue 1. Additionally, traversing normal kidney tissue may contaminate the sample with normal tissue, potentially leading to sampling error and inaccurate diagnosis.

When planning an RCC biopsy, imaging guidance (ultrasound or CT) should be used to map the safest and most direct route to the tumor, as recommended by the European Association of Urology guidelines on renal cell carcinoma 1. In cases where traversing normal kidney tissue is unavoidable due to tumor location, using a coaxial technique with a guiding cannula can help minimize the risk of tumor seeding, and the smallest gauge needle that will provide adequate tissue should be selected to reduce trauma to normal kidney tissue. It is also important to consider the use of non-ionizing modalities, such as MRI and contrast-enhanced ultrasound, for further characterization of small renal masses, tumor thrombus, and differentiation of unclear renal masses if results for contrast-enhanced CT are indeterminate 1.

Key considerations in the management of RCC include:

• The use of multiphase contrast-enhanced CT of the abdomen and chest for the diagnosis and staging of renal tumors 1
• The importance of individualizing treatment decisions for frail patients, weighing the risks and benefits of partial nephrectomy versus radical nephrectomy, and considering the risk of developing or worsening chronic kidney disease postoperatively 1
• The recommendation to perform a renal tumor biopsy before ablative therapy and systemic therapy without previous pathology, and to use a core biopsy technique rather than fine needle aspiration for histological characterization of solid renal tumors 1.

Overall, the goal of RCC management is to achieve cure in localized disease, while minimizing morbidity and mortality, and optimizing quality of life 1.

From the Research

Biopsy of Renal Cell Carcinoma (RCC)

• The decision to biopsy a renal mass, including RCC, is crucial for diagnosis and treatment planning 2, 3.
• Renal biopsy is reported as a safe procedure with a low complication rate, as seen in a study where the complication rate was 4.8% overall, with all complications being Clavien grade I and without serious sequelae 2.
• The use of imaging techniques such as ultrasound (US) and computerized tomography (CT) is essential in the diagnosis of RCC, but discrepancies between US and CT findings may occur, highlighting the need for renal biopsies in such cases 3.

Traversing a Normal Kidney for Biopsy

• There is no direct evidence in the provided studies to support or refute the practice of traversing a normal kidney to biopsy a RCC.
• However, the studies suggest that renal biopsy is a safe and effective procedure, with a high concordance between biopsy results and definitive pathology 2.
• The decision to perform a biopsy and the approach used (US-guided or CT-guided) should be based on individual patient factors and the specific clinical scenario, taking into account the potential risks and benefits 2, 4.

Diagnostic Challenges and Considerations

• RCC can present differently on US and CT scans, and renal biopsies may be necessary to confirm the diagnosis, especially in cases where imaging findings are discordant 3.
• Fat necrosis can mimic RCC recurrence on imaging, highlighting the need for careful evaluation and consideration of alternative diagnoses in patients with a history of RCC 5.
• The American College of Radiology Appropriateness Criteria provide guidelines for the use of imaging modalities in the follow-up and active surveillance of patients with clinically localized RCC 6.