[1053] Unclassified Renal Cell Carcinoma and Invasive High Grade Urothelial Carcinoma: Is the Distinction Possible by Immunohistochemistry and Clinically Important?

Katherine E Watts, Jordan P Reynold, Paula Carver, Ming Zhou. Cleveland Clinic, Cleveland, OH

Background: The differential diagnosis for a poorly differentiated carcinoma in the kidney includes renal cell carcinoma (RCC) and urothelial carcinoma (UC). Such distinction is presumed to be clinically important as the chemotherapeutic and surgical regimens for them are different. This study aimed to investigate: 1) whether a panel of immunostain markers could differentiate between poorly differentiated RCC and UC, and 2) whether the distinction between the two is clinically important?
Design: A tissue microarray was constructed to include 11 unclassifiable RCC (including 3 with features of collecting duct RCC), 2 renal UC and 16 invasive high grade pelvic UC and was stained with a panel of markers (PAX-8, K903, p63, CK7, CK20). Clinical information was obtained by chart review and patient contact.
Results: The mean age of RCC and UC patients was 60.3 (range 45-81) years and 70.1 (range 54-95) years. The male/female ratio was 9/2 for RCC and 13/5 for UC patients. PAX-8, K903, p63, CK7 and CK20 were positive in 10, 0, 0, 2 and 2 of 11 RCC, and 3, 9 18, 17 and 7 UC, respectively. Therefore, a PAX-8 positive/K903 negative/p63 negative phenotype identified 10/11 (90.9%) RCC, and a PAX-8 negative/K903 or p63 positive phenotype identified 15/18 (83.3%) UC. The follow-up for RCC patients was an average of 11 months, and in UC patients was an average of 10.4 months. 9/11 (81.9%) RCC patients and 13/18. (72.2%) UC patients died of disease, which was not found to be statistically significant (p=0.55).
Conclusions: Immunostains using a panel of markers (PAX-8, K903 and p63) could reliably distinguish poorly differentiated RCC and invasive high grade UC. However, all these patients had extremely poor prognosis; therefore, the distinction between the two tumors seem to be of limited clinical prognostic significance.
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 151, Tuesday Morning


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