In this study we have investigated immunohistochemical biomarkers (cytokeratin 7/CK7, Caveolin-1/Cav-1 and S100 calcium-binding protein A1/S100A1) to aid in this difficult differentiation and attempted to validate their use in human renal tumour tissue to assess their discriminatory ability, particularly for chRCC and RO, in an Australian cohort of patients.
S100A1 was moderately-to-strongly positive in 45 of 56 (80%) RO and in 1 of 13 (8%) ChRCC (P < .001), with 39 of 56 (70%) and 2 of 13 (15%) cases, respectively showing positivity in >50% of tumor cells (P< .001).