Renal mass biopsy (RMB) is a procedure that involves taking a small sample of tissue from a kidney tumor and examining it under a microscope. RMB can help diagnose the type and grade of the tumor, as well as guide the treatment plan. However, the utility of RMB for large renal masses (>7 cm) is still controversial, as some studies have suggested that it may not be accurate or reliable enough.
A recent study published in Research and Reports in Urology aimed to evaluate the utility of RMB in large renal masses and compare it with the final pathology results after surgery. The study included 103 patients who underwent RMB for renal masses larger than 7 cm between 2014 and 2020. The researchers analyzed the concordance rate, sensitivity, specificity, positive predictive value, and negative predictive value of RMB for different histological types and grades of renal tumors.
RMB Results Matched with Final Pathology in Most Cases
The study found that RMB results matched with the final pathology results in 88.3% of cases for histological type and 76.7% of cases for histological grade. The most common histological type was clear cell renal cell carcinoma (RCC), followed by papillary RCC and chromophobe RCC. The most common histological grade was Fuhrman grade 2, followed by grade 3 and grade 4.
The concordance rate of RMB for histological type was higher for clear cell RCC (94.9%) than for non-clear cell RCC (66.7%). The concordance rate of RMB for histological grade was higher for Fuhrman grade 2 (86.8%) than for grade 3 (69.6%) or grade 4 (50%). The sensitivity, specificity, positive predictive value, and negative predictive value of RMB for histological type and grade were also calculated and reported in the study.
RMB Can Help Avoid Unnecessary Surgeries
The study also highlighted the clinical implications of RMB for large renal masses. The researchers noted that RMB can help avoid unnecessary surgeries for benign tumors or low-grade malignancies that can be managed conservatively or with minimally invasive techniques. For example, in their study, 11 patients had benign tumors and 9 patients had low-grade malignancies that were diagnosed by RMB. These patients were spared from radical nephrectomy, which is a major surgery that involves removing the entire kidney and can have significant complications and impact on quality of life.
The researchers also pointed out that RMB can help select the appropriate surgical approach for malignant tumors, such as partial nephrectomy, radical nephrectomy, or cytoreductive nephrectomy. For instance, in their study, 15 patients had high-grade malignancies that were diagnosed by RMB. These patients underwent radical nephrectomy or cytoreductive nephrectomy, which are more aggressive surgeries that aim to remove all the tumor tissue and prevent metastasis.
RMB Is a Safe and Feasible Procedure
The study also demonstrated that RMB is a safe and feasible procedure for large renal masses. The researchers reported that none of the patients had any major complications from RMB, such as bleeding, infection, or tumor seeding. The only minor complication was pain at the biopsy site, which was managed with analgesics. The researchers also noted that RMB has a high success rate, as only 3 patients had inadequate samples that required repeat biopsy.
The researchers concluded that RMB is a useful tool for large renal masses, as it can provide accurate and reliable information on the histological type and grade of the tumor, as well as guide the treatment plan and avoid unnecessary surgeries. They recommended that RMB should be performed routinely for large renal masses before deciding on the surgical approach.