Xp11.2 translocations in adult renal cell carcinomas with clear cell and papillary features.

4613 Background: Xp11.2 translocation renal cell carcinoma (RCC) is a rare tumor with unpredictable clinical course and prognosis in adults. Recognition of these tumors depends on the identification of a RCC with unique histology, particularly clear cell and papillary (CCP) features. Our objectives were to determine the incidence of Xp11.2 translocations in adult RCCs with clear cell and papillary features, and to characterize the clinicopathological features and prognosis of adult Xp11.2 RCCs. Methods: Slides for 1047 RCCs in adults (1999-2009) were retrieved from multiple institutions. Cases were reviewed histologically in order to detect any degree of clear cell and papillary change. Tissue microarrays were constructed from the clear cell and papillary RCCs as well as 40 non-papillary clear cell, 5 papillary, 3 chromophobe and 2 unclassified RCCs. Immunohistochemistry using TFE3, a marker highly sensitive (97.5%) and specific (99.6%) for Xp11.2 translocations was performed. Four pathologists independen...