San Antonio, Texas USA (UroToday.com) In this session, Dr. Bill Huang moderated a panel discussion on the utility of renal mass biopsy in the diagnosis and management of the small renal mass. Historically, renal mass biopsy had a limited role.
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This was due to the high diagnostic accuracy of cross sectional imaging, high false negative rates of biopsy, and the relatively high potential for biopsy-associated complications. Therefore, biopsy was limited to patients with prior malignancies, disseminated metastatic renal cell carcinoma (RCC), unresectable tumors, or bilateral multifocal tumors. However, improving biopsy techniques and accuracy have reinvigorated a debate about the appropriate clinical scenarios for renal mass biopsy. On one hand are those who believe that renal mass biopsy should be universally performed in patients with small renal masses (Richard et al, Eur Urol 2015, 68, 1007). On the other hand are those who argue for a more nuanced approach (Kutikov et al, Eur Urol 2016, 70, 403). So, where are we in 2016?
The panel discussed several cases of incidentally detected small renal masses to tease out the ideal indications for renal mass biopsy. For all patients, management options for small renal masses elaborated by the panel consisted of active surveillance, ablation, and surgical excision. The panel did not universally recommend renal mass biopsy. Rather, biopsy was favored in patients with prior malignancies or in situations where biopsy would help inform and potentially change the management decision between surveillance and treatment.
Dr. Chen discussed some of the limitations in rendering accurate pathologic diagnoses on renal mass biopsy tissue. For common renal histologic subtypes, the diagnostic rates are quite good; however, as more renal histologic subtypes are being defined, some challenges remain for the rarer subtypes. Diagnostic accuracy regarding grade in small renal masses is meaningful if a high-grade diagnosis is rendered. In contrast, the concordance between a low-grade biopsy diagnosis and the final surgical pathology is only about 50% due to challenges associated with tumor heterogeneity. Thus, problems in accurately determining tumor grade on biopsy tissue remain.
Dr. Parsons spoke eloquently about trying to perform histologic subtyping using imaging. The progress in this space is encouraging. However, she cautioned the audience that tremendous overlap in imaging appearance among renal masses remains. For example, while papillary tumors are typically hyperdense on computed tomography and hypointense on T2 weighted magnetic resonance imaging sequences, these features are not specific. Rather, there is considerable overlap between papillary tumors and fat poor angiomyolipomas. Thus, while great potential exists to use imaging for the purposes of subtyping, the technology is not quite there to definitively classify on subtype based on imaging.
In conclusion, the SUO panel put forth a nuanced discussion of appropriate renal mass biopsy. It seems the consensus remains that renal mass biopsy should be performed “more than never, but less than always.” (Kutikov et al, Eur Urol 2016, 70, 403).
Moderator: William C. Huang, MD
Panelists: Ying-Bei Chen, MD, PhD, Todd M. Morgan, MD, Rosaleen B. Parsons, MD, FACR, FSAR, R. Houston Thompson, MD, and Christopher G. Wood, MD, FACS
Written By: Benjamin T. Ristau, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center
17th Annual Meeting of the Society of Urologic Oncology - November 30 -December 2, 2016 – San Antonio, Texas USA