Fig. 2

a The non-encapsulated tumor was sharply demarcated from the adjacent renal parenchyma (H&E staining, × 40). b The neoplasm consisted of polygonal tumor cells with clear and granular cytoplasm arranged in nests and cords delimited by thin-walled fibrovascular septa as well as numerous neoplastic cells containing intracytoplasmic brown pigment that were found throughout the lesion (H&E staining, × 100). c Occasional nuclear pseudoinclusions (arrow) were present (H&E staining, × 200). d Thick-walled blood vessels were observed(H&E staining, × 100)