Should a biopsy be performed on a suspicious renal (kidney) mass?

From the Guidelines

Yes, a biopsy should be performed on a suspicious renal mass.

Indications for Biopsy

The indications for renal mass biopsy have expanded in recent years due to the increasing incidence of incidental small renal masses and the development of minimally invasive treatment and active surveillance strategies for low-risk RCC 1.

• Benign renal tumors, such as lipid-poor AML and oncocytoma, can mimic RCC at imaging, and biopsy can help guide decision making aimed at minimizing kidney function loss 1.
• Biopsy should be strongly considered when there are imaging features suggestive of a benign mass, such as a fat-poor AML 1.
• Decision-modeling studies have suggested that percutaneous biopsy can prevent unnecessary surgery in many cases 1.

Benefits and Limitations of Biopsy

• Renal mass biopsy may assist clinical management in patients with limited life expectancy or significant comorbidities 1.
• Significant biopsy-related complications are infrequent, with one study reporting significant complications in 0.9% of patients 1.
• An important limitation of biopsy is the rate of nondiagnostic results, especially for small renal masses, with one study reporting a diagnostic rate of 80.6% for biopsies of renal masses <4 cm 1.

Clinical Management

• The results of the biopsy can be used to guide decision making, with active surveillance being chosen in cases of benign or favorable histology 1.
• In patients with significant medical comorbidities, active surveillance may be a better option than surgical intervention or ablation 1.
• The optimal indications for partial nephrectomy, radical nephrectomy, or thermal ablation depend on various factors, including the size and location of the tumor, as well as the patient's overall health and life expectancy 1.

From the Research

Indications for Renal Biopsy

• A renal biopsy is indicated for suspicious renal masses to determine the presence of malignancy and to guide clinical management 2, 3, 4.
• The procedure is safe, reliable, and accurate, with a low risk of major complications 2, 3, 5, 6.
• Renal biopsy can help avoid unnecessary nephrectomy or other surgical options in cases where the mass is benign or non-malignant 2, 3, 4.

Diagnostic Accuracy of Renal Biopsy

• The diagnostic accuracy of renal biopsy for renal masses is high, with a sensitivity and specificity of 93% and 87% for peripheral biopsies, and 90% and 93% for central biopsies, respectively 6.
• The overall accuracy of renal biopsy for subclassification of renal masses is 76% 3.
• Renal biopsy can accurately identify malignancies, with a concordance rate between biopsy and surgical pathology of 97.1% 5.

Predictors of Successful Renal Biopsy

• Small tumor size, cystic nature of tumors, and biopsy during the initial years of the study are independent predictors of nondiagnostic biopsy 5.
• A second biopsy should be considered in cases where the initial biopsy is nondiagnostic 5.
• The presence of necrosis on CT scans and cigarette smoking are associated with an increased risk of malignancy in renal masses 6.

Clinical Management Based on Renal Biopsy Results

• Renal biopsy results can significantly impact clinical management, with 41% of patients avoiding nephrectomy or other surgical options due to a benign or non-malignant diagnosis 2, 3.
• Chemoradiation can be avoided in patients with a diagnosis of benign tumors or lesions, and primary renal carcinoma 3.
• Active surveillance is a viable option for patients with benign conditions or small renal masses 3, 5.