Figure 1.

Computed tomography scan and macroscopic findings. A round hypodense mass in the upper pole of the left kidney (A, B, arrows). The tumor with a diameter of 2.2 cm was ill-demarcated, and its cut surface showed brownish-white in color (C, arrow)."

Figure 2.

Microscopic findings of HE staining. The tumor had an indefinite fibrous capsule (A, ×40), and in some area it seemed that tumor cells broke through the capsule (B, ×40, arrow). The tumor consisted of sheets or nests of large polygonal cells with pale or eosinophilic cytoplasm (C, ×400) and abundant arborizing capillary network (D, ×400). Lipoblast-like cells with multiple vacuolization (C), rhabdoid cells (E, ×400, arrow), and hyalinization (F, ×100) were focally seen."

Figure 3.

Immunohistochemical and histochemical findings. SP ×100 Neoplastic cells were diffusely positive for vimentin (A), NSE (B), S100 protein (C), α-inhibin (D), and focally positive for CD10 (E). Eosinophilic globules imparted a positive reaction to periodic acid-Schiff stain with diastase treatment (F, arrow)."

Figure 4.

VHL gene molecular analysis. A. All three exons of VHL gene were detected by using polymerase chain reaction, and a gene mutation was found in exon 2. B. By gene sequencing analysis, we found a single base deletion (T)."