[1058] Multilocular Cystic Renal Cell Carcinoma: Similarities and Differences in Immunoprofile Compared to Clear Cell Renal Cell Carcinoma

Sean R Williamson, Shams Halat, John N Eble, David J Grignon, Antonio Lopez-Beltran, Rodolfo Montironi, Puay Hoon Tan, Mingsheng Wang, Shaobo Zhang, Gregory T MacLennan, Liang Cheng. Indiana University School of Medicine, Indianapolis; Oschner Medical Center, New Orleans; Cordoba University, Cordoba, Spain; Polytechnic University of the Marche Region (Ancona), Ancona, Italy; Singapore General Hospital, Singapore; Case Western Reserve University, Cleveland

Background: Multilocular cystic renal cell carcinoma (RCC) is an uncommon renal neoplasm, composed of thin fibrous septa lining multiple cystic spaces, associated with an excellent prognosis. Clear cells with generally low-grade nuclear features line cystic spaces and may be present within fibrous septa. Solid mass-forming areas are by definition absent. Findings in a recent study suggested that multilocular cystic RCC is a subtype of clear cell RCC. Immunohistochemical staining characteristics, however, have not been well elucidated.
Design: We studied 19 cases of multilocular cystic RCC, classified according to the 2004 WHO System. Immunohistochemistry was performed on an automated immunostainer for CD10, CK7, alpha-methylacyl-CoA-racemase (AMACR), epithelial membrane antigen (EMA), cytokeratin CAM 5.2, carbonic anhydrase IX (CA-IX), estrogen/progesterone receptors (ER & PR), smooth muscle actin (SMA), PAX-2, and vimentin. Nineteen cases of grade 1-2 clear cell RCC were stained for comparison.
Results: Multilocular cystic RCC and control cases of clear cell RCC showed the following results, respectively: CD10 (58%, 94%), CK7 (89%, 26%), AMACR (16%, 47%), vimentin (42%, 16%), ER (10%, 10%), EMA, CAM 5.2, CA-IX, PAX-2 (all 100%), PR and SMA (both 0%).
Conclusions: Tumors showed expression of common clear cell RCC markers CA-IX, EMA, and PAX-2, in support of the hypothesis that multilocular cystic RCC is a subtype of clear cell RCC. In contrast to clear cell RCC, tumors were less likely to express CD10 (58%) and more likely to express CK7 (89%). Of note, coexpression of CA-IX and CK7 represents a point of overlap with the recently described clear cell papillary RCC, which also may show a prominent cystic architecture. However, no cases of the latter have exhibited deletion of chromosome 3p by molecular testing.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 87, Wednesday Morning


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