Contributed by Zaibo Li, MD, PhD, Amber Henry Hughes, MD and Rajiv Dhir, MD
51-year-old woman presented with chronic fatigue and weakness for approximately 6 months. A CT scan showed a large left renal mass. The patient underwent radical nephrectomy.
A mass is located in the upper pole and measures 15 x 9 x 8.5 cm. On cut section, the tumor is yellowish with whitish area and occasional hemorrhagic areas, and no apparent necrosis is identified. The tumor is very close to the vessel, but not grossly invades into the vascular wall. Ureter and pelvis appear to be involved by tumor.
The tumor is composed of sheets and nests of apparently poorly-differentiated round cells separated by sparse intervening stroma. These cells show characteristic hyperchromatic nuclei with stippled chromatin and inconspicuous nucleoli. The cytoplasm is scant in some cells, but is eosinophilic in other cells. Mitoses are numerous (Figures 3. 4 and 5). Vascular invasion (Figure 6) and perineural invasion (Figure 7) are present. Metastatic tumor is also present in hilar lymph nodes (image not shown).
Immunostains for CA9, CD10, CK7, CD56 and synaptophysin were performed and the representative images are shown (Figures 8, 9, 10, 11 and 12).