Bilateral multifocal papillary type I renal cell carcinoma: Clinical characteristics and association with chronic renal insufficiency.

482 Background: Patients with bilateral multifocal (BMF) RCC are at risk for multiple surgeries, progressive loss of renal tissue and chronic renal insufficiency. Although BMF papillary type I RCC is commonly associated with Hereditary Papillary Renal Cell Carcinoma (HPRC), with mutation of the MET proto-oncogene, sporadic (non-familial) BMF Pap1 RCC is far more common. Here we describe the histologic and clinical phenotype as well as clinical management of a population of patients with BMF RCC that has papillary type I histology that is distinct from the HPRC population. Methods: From 2000 to 2013, patients who were evaluated at the National Cancer Institute and were diagnosed with BMF on cross sectional imaging were included. Patients who tested negative for MET proto-oncogene mutation, who have a pathologic diagnosis of papillary type I were included. Phenotypic manifestations and clinical management were analyzed. Results: 61 patients with an average age of 54.3 years were identified. A disproportionate number (22, 36%) of these patients were of African American descent. Fifty seven (93%) were male. Two patients were found to have had metastatic disease on presentation (3%); 17 patients underwent unilateral radical nephrectomy for renal mass (28%) even though the average largest tumor diameter was only 2.9 cm. 12 patients (19%) underwent partial nephrectomy. The average preoperative serum creatinine was 1.48 mg/dl and average eGFR 62.2 ml/min, there was no difference between in eGFR in African American patients and Caucasian patients (62.09 ml/min and 63 ml/min). This population had an average of 2 tumors per side, many patients also had numerous cysts on both kidneys. Conclusions: BMF papillary type I RCC represents a novel entity which disproportionally affects African Americans. These patients often present with renal insufficiency and are at significant risk for further renal deterioration. As a small percentage of these patients with BMF papillary type I will present with metastatic disease, active surveillance until the largest renal tumor reaches 3 cm is recommended.