Contributed by Angela Sanguino Ramirez MD, MPH; Thu Tran MD and Rajiv Dhir MD
An 80 plus year-old female with past medical history of coronary disease was found to have an incidental mass in the right kidney during an ultrasound performed for a recent elevated creatinine level. No previous history of chronic renal failure, hypertension or diabetes was reported.
CT scan and an MRI showed a 3.8 cm partially cystic, enhancing lower pole mass in the right kidney, measuring 2.8 cm in greatest dimension.
The patient was admitted for right partial nephrectomy.
The excised partial nephrectomy show a 3.3 cm cystic mass, partially hemorrhagic with no gross extension into the renal parenchyma or capsular resection margin. Microscopic examination shows a solid and cystic neoplasia with solid, papillary and tubular architecture (FIGURE 1). The neoplastic cells have clear cytoplasm, small and bland nuclei with inconspicuous nucleoli. Within the solid areas the neoplasia shows morphologically features similar to clear cell renal cell carcinoma (FIGURE 2). Focally, there was a region with tubular and papillary architecture where the nuclei are aligned away from basement membrane, similar to the subnuclear vacuoles of early secretory endometrium. (FIGURES 3, 4 and 5) By immunohistochemistry, the neoplastic cells are diffusively positive for CK7 (FIGURE 6). Carbonic anhydrase IX (CA-IX) stains positive in the basolateral lining of cells (cup-like pattern) (FIGURES 7 and 8). CD10 positivity is limited to the cystic areas staining only cystic lining cells (FIGURES 9 and 10). Racemase is negative (Not shown).