#AUA14 - Incidence of hybrid tumors found in excised renal masses: A multi-institutional analysis - Session Highlights

ORLANDO, FL USA (UroToday.com) - Renal biopsy for small renal masses, specifically those less than 4cm in size, is becoming more popular given improved techniques. David Fumo in their studies wanted to quantify the prevalence of tumors with multiple histologies in order to assess the accuracy of renal biopsy.

This was a multi-institutional study, where authors retrospectively studied RCC cases from 1998-2012. Patients who did not have information on pathologic stage, size, and histology were excluded from the study. The authors considered tumors to be hybrid if they had more than one histologic subtype.

auaThey identified 427 tumors that fit the criteria for analysis. Forty-eight tumors displayed hybrid characteristics based on the authors’ definition. There were no differences between the two groups with regards to mass size, stage, and age. The majority of the hybrid tumors were stage T1a and contained a combination of clear cell and papillary histology. Half of the hybrid tumors were smaller than 4cm. Seven out of 48 hybrid tumors contained a mixture of malignant and benign characteristics.

The authors concluded that most of the hybrid tumors in their cohort were low-stage tumors. Only a small percentage contained both benign and malignant components. This low percentage of tumors that contain both benign and malignant components is important because it allows renal biopsy to reliability assess a renal mass. The findings are significant clinically in that when a benign finding is found upon renal biopsy, urologists may be able to reassure patients that they are unlikely to have a malignancy. However, the accuracy of biopsy devices will need to be adjusted for this association. In addition, review of actual histology slides will need to be performed to confirm the previously reported pathology results.

Presented by David Fumo, MD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA

Hackensack, NJ USA

Written by Garen Abedi, MD, University of California (Irvine), and medical writer for UroToday.com