Contributed by Shveta Hooda, MD and Anil V Parwani, MD, PhD
A 69 year old African American female on hemodialysis for chronic renal failure was found to have a 2.6cm enhancing renal mass in the posterior right renal mid pole on abdominal CT scan. The patient underwent a laparoscopic nephrectomy. Her past medical history is significant for diabetes, hypertension, coronary artery disease status post coronary artery bypass graft and hyperlipidemia.
The gross examination of the nephrectomy specimen showed a well circumscribed tan yellow mass with cystic areas in the mid portion with a maximum dimension of 2.4 cm. The histologic sections showed the tumor delimited by a fibrotic capsule (Figure 1) and composed of clear cells with tubulocystic and papillary components. The nuclei had a Fuhrman grade of 2 and were arranged in a linear manner mostly in the center of the cells (Figure 2). No mitotic figures or areas of necrosis were seen. No angiolymphatic invasion was identified. All surgical margins were free of tumor. The TNM stage was pT1a.
The results of immunostains are summarized in Table 1.
|Cytokeratin7 (Figure 3)||Strong positive|
|Carbonic anhydrase 9 (Figure 4)||Strong positive|