Biopsy of Renal Masses 1. Biopsy is not necessmy before excision of a primary solid renal mass because most of these lesions are malignant. Although biopsy is not part of the standard evaluation, it can be considered when: a. There is suspicion that the renal lesion may be infectious, inflammatory, angiomyolipoma, lymphoma, or a tumor metastatic to the kidney. b. A surgical candidate chooses to undergo surveillance, ablation, or embolization rather than nephrectomy. The 2009 AUA guideline states that renal biopsy is not indicated ...for older patients who will only consider conservative management options regardless ofbiopsy results. c. To confirm the diagnosis ofRCC before systemic therapy in a patient with metastases who is not a candidate for cytoreductive nephrectomy. In this case, the renal lesion or a metastatic lesion may be biopsied. 2. Biopsies of a renal mass are nondiagnostic in up to 20% of cases. 3. False negatives occur in 1-2% ofbiopsies when adequate tissue is obtained. A false negative biopsy can occur when a benign tumor coexists with RCC (although rare, RCC can coexist with oncocytoma). 4. Side effects-bleeding or infection are serious in < 2% of cases. Tumor spread along the biopsy tract occurs in< 0.1% of cases. Pe7form the biopsy using a coaxial technique through a cannula to minimize the risk of tumor seeding along the biopsy tract. Biopsy of a cystic mass may have a higher risk of tumor spillage. 5. Metastatic melanoma and AML stain positive for HMB-45. If a biopsy of a primary renal tumor stains positive for HMB-45, it is probably an AML.
Posted on: Fri, 26 Dec 2014 23:04:24 +0000