Presentation Authors: Arun Menon*, Aly Ahmed, Tashionna White, Gaybrielle James, Paul May, Eric Kauffman, Buffalo, NY
Introduction: The tumor:cortex peak early-phase enhancement ratio (PEER) using multiphase CT has been prospectively validated for discerning CD117(+) chromophobe RCC from CD117(+) oncocytoma. We evaluate the effectiveness of routine preoperative biopsy and PEER evaluation to prevent resection of benign kidney tumors.
Methods: We retrospectively reviewed the pathology of all fat poor renal cortical tumors resected over a 5 year period by a single surgeon at a National Comprehensive Cancer Care Network institute who used the approach of routine biopsy combined with oncocytic tumor:cortex PEER evaluation to select patients for surgical resection. Biopsy was routinely performed for any renal cortical tumors with suspicion of benign histology. Biopsy showing benign oncocytoma were observed. CD117 positive oncocytic tumors suggestive of oncocytoma were confirmed to be oncocytoma on a tumor:cortex PEER value of more than 0.55.We looked at pathology of all resected renal cortical tumors over a 6 year period using this approach to determine the incidence of benign vs malignant histology.In parallel, we also determined the number of patients with benign renal tumor suggested on biopsy who went on active surveillance and avoided initial resection using this approach. Outcomes of benign tumor on surveillance, including progression and metastasis rates were reviewed.
Results: 167 patients with a preoperative diagnosis of renal cell carcinoma underwent surgery. 106 (63.47%) patients were diagnosed as malignant renal tumor on preoperative biopsy. 61 (36.52%) patients with frank features of malignancy clinically or on imaging directly proceeded to surgery without a biopsy. On review of the final resected tumor histopathology, no instance of resection for a benign tumor was found. One patient with a preoperative diagnosis of spindle cell tumor was found to have Epitheloid Angiomyolipoma with necrosis and indeterminate malignant potential on final pathology. During the same period, 35 patients were determined to have benign renal tumor on biopsy and PEER evaluation. These patients did not undergo surgery and were placed on surveillance. Over a median follow up of 24 months, no patient developed progression or metastasis.
Conclusions: A combination of routine biopsy for tumors with potential for benign histology and the PEER approach for discerning CD117(+) oncocytoma from CD117(+) chromophobe RCC is an effective diagnostic tool to avoid resection for benign tumors.