[Diagnostic utility of immunohistochemistry in differential diagnosis of renal tumors with oncocytic features].

Objective: To investigate the morphological features and immunophenotypes of eosinophilic renal tumors in order to provide references for the differential diagnosis of this tumor. Methods: A cohort of 75 cases of eosinophilic renal tumors were collected. The morphological features of the tumors were observed under microscope, and the immunophenotypes of the tumors were detected using tissue microarray and immunoshistochemistry. Results: There were some overlaps between the different types of eosinophilic renal tumors in morphology, but each had its distinct characteristics. Immunohistochemically, renal oncocytoma (RO) and eosinophilic chromophobe renal cell carcinoma (ChRCC) shared some common immumophenotypes, except for the expression of CK7, with the expression rates of 2/19 in RO and 17/20 in eosinophilic ChRCC, respectively. Eosinophilic clear cell renal cell carcinoma mainly showed positive immunostaining for Vimentin and CAⅨ, whereas negative for CK7 and CD117 in most cases (10/15). AMACR was diffusely expressed in the majority of eosinophilic papillary renal cell carcinoma (PRCC, 10/13). Furthermore, vimentin, CK7 and CD10 were positively expressed in eosinophilic PRCC with the expression rates of 8/13, 9/13 and 6/13, respectively; while CAⅨ, CD117 and TFE3 were all negatively expressed in eosinophilic PRCC.Epithelioid angiomyolipoma generally showed positive expression of vimentin, SMA and HMB45, but negative expression of CAⅨ and CK7. Vimentin, CD10, AMACR and TFE3 were strongly expressed in XP11.2 translocation renal cell carcinoma; on the contrary, CK7, CD117 and HMB45 were not expressed in the majority of the tumor. Conclusion: With full understanding of the morphology of different types of eosinophilic renal tumors, the immunostaining of vimentin, CAⅨ, CK7, CD10, AMACR, CD117, TFE3 and HMB45 could play a crucial role in the differential diagnosis of these tumors.