Dr. Obek presented to an audience of urologists that a renal mass biopsy is clearly underutilized. Renal mass biopsy is often an office procedure with no need for hospitalization. It has a relatively short learning curve (a few dozen cases) and can be safely performed by a urologist rather than a radiologist in most cases. The biopsy is ultrasound-guided and thus obviates the need for CT scanners at a hospital setting. Since renal tumors are highly heterogeneous, it is recommended to sample at least 2 cores using an 18-gauge needle. Core needle biopsy is considered superior to aspiration.
Renal mass biopsy is a safe procedure with an acceptably low rate of mainly minor complications. The most common complication is a subcapsular or perirenal hematoma. It is largely subclinical, does not require treatment, and the need for blood transfusion or angioembolization is rare. Hematuria can appear in 5% of patients but it is self-limiting and does not require intervention. Other complications such as pneumothorax or infection are rare. Tumor seeding is exceedingly rare, and only a few case reports are found in the literature.
Ten to 20% of renal mass biopsies are nondiagnostic. This is mostly true for small, endophytic, and cystic lesions. With continuous improvements in imaging and biopsy techniques, the actual rate of nondiagnostic biopsies is around 10%. A repeat biopsy, however, is diagnostic in 80-100% of cases. Sensitivity and specificity of renal mass biopsy are both 96-99%, and are noninferior, if not superior to biopsies of other solid organ tumors. The diagnostic accuracy for tumor grade using the 4-grade system is 63%. However, when using low (grade 1-2) or high (grade 3-4) grading system, accuracy increases to 88%.
In conclusion, renal mass biopsy is an office procedure that can often be performed by a urologist using ultrasound guidance. It is a safe procedure with lower complications rate. The diagnostic accuracy is comparable to biopsies of other solid organs. Biopsy of small renal masses, however, remains underutilized among urologists.
Presented by: Can Obek, MD, Professor, Department of Urology, Acibadem Taksim Hospital, Istanbul, Turkey
Written by: Shlomi Tapiero, MD, Department of Urology, University of California-Irvine, medical writer for UroToday.com at the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France
Read: State of the Art: Small Renal Masses, the Moderated Session by Jaime Landman, MD
Read:State of the Art: Small Renal Masses – Active Surveillance by David Duchene, MD
Read: State of the Art: Small Renal Masses - Imaging by Francesco Porpiglia, MD
Read: State of the Art: Small Renal Masses – Latest in Partial Nephrectomy, Duke Herrell, MD