An immunohistochemical diagnostic panel for Xp11.2 translocation renal cell carcinoma: A diagnostic accuracy study

Transcription factor binding to IGHM enhancer 3 (TFE3) break-apart fluorescence in situ hybridization (FISH) is the gold standard for the diagnosis of Xp11.2 translocation renal cell carcinoma (tRCC). However, FISH is costly and not accessible in all laboratories. We aimed to develop a surrogate immunohistochemical panel to recognize Xp11.2 tRCC. We retrospectively enrolled 84 patients who underwent surgery for renal lesions from September 2017 to August 2022. Both immunohistochemistry and FISH analysis were performed on their specimens. The sensitivity, specificity, and accuracy of each immunohistochemical marker and combinatorial immunohistochemical panels were calculated. A total of 17 patients were diagnosed with Xp11.2 tRCC using FISH. In patients with Xp11.2 tRCC, 77% (13/17), 100% (17/17), 88% (15/17), 88% (15/17), 100% (17/17), and 71% (12/17) were tested positive for AE1/AE3, CD10, P504S, PAX8, TFE3, and vimentin, respectively, while 94% (16/17) were tested negative for cytokeratin 7 (CK7). The immunohistochemical panel combining negative CK7, positive CD10, positive P504S, and positive TFE3 exhibited a sensitivity of 0.824, a specificity of 0.672, and a highest accuracy of 0.702. The immunohistochemical panel combining negative CK7, positive CD10, positive P504S, and positive TFE3 was a potentially useful tool for the diagnosis of Xp11.2 tRCC.