Fig. 2

Hematoxylin/eosin staining (a) showing that the cyst wall is lined by a monolayer of cuboidal tumor cells. × 100 magnification. Hematoxylin/eosin staining (b) showing tumor cells in the solid areas arranged into a papillae pattern, as well as an enlarged nucleus with prominent eosinophilic nucleoli and a peripheral halo × 200 magnification. Immunohistochemistry (c) showing positive nuclear expression of PAX8 protein in the tumor cells × 200 magnification. Immunohistochemistry (d) showing the absence of Fumarate hydratase protein in the tumor cells; additionally, the nonneoplastic renal cells that served as the internal control showed granular positive expression in the cytoplasm. × 200 magnification