21 Decoding Kidney Tumours: A Comparative Study of Immunohistochemical Markers in Renal Oncocytoma and Chromophobe Renal Cell Carcinoma

Abstract Introduction Renal oncocytoma and Chromophobe Renal Cell Carcinoma (ChRCC) are similar benign kidney tumours, but they have distinct histological and clinical differences. Accurate diagnosis is crucial, yet current methods face challenges. This study aimed to compare the diagnostic accuracy of various immunohistochemistry (IHC) markers. Method We analysed 100 cases of renal tumours between 2010 and 2022. IHC was performed using different markers, including cytokeratin 7 (CK7), cytokeratin 20 (CK20), CD117, CD10, Hale's colloidal iron, and parvalbumin. The results of IHC staining were categorised as positive, negative, or equivocal. We calculated the sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV), and accuracy of each marker. Results Of the 100 cases analysed, 51 were male and 49 were female. Baseline characteristics of the patients were similar between the two groups. CK7 showed the highest sensitivity (86%), followed by CD117 (76%) and CK20 (54%). Hale's colloidal iron had the highest specificity (96%), followed by CD10 (92%) and CK20 (88%). CD117 had the highest PPV (96%), followed by CK7 (91%) and CK20 (79%). Hale's colloidal iron had the highest NPV (91%), followed by CK20 (83%), and CD10 (80%). The combination of CK7 and Hale's colloidal iron showed the highest accuracy (90%). Conclusions CK7, CD117, and CK20 are the most accurate IHC markers for distinguishing renal oncocytoma from ChRCC. Hale's colloidal iron and CD10 also show promise. Using CK7 and Hale's colloidal iron together significantly improves diagnostic accuracy. IHC markers can be valuable tools for differentiation, but larger studies in diverse populations are needed for confirmation.