[795] Renal Cell Carcinoma with Extensive Clear Cell Component and Papillary Architecture: Value of Immunohistochemistry.

Lei Duan, Ramy F Youssef, Vitaly Margulis, Yair Lotan, Prasad Koduru, Wareef Kabbani, Payal Kapur. University of Texas Southwestern Medical Center, Dallas

Background: The current classification of renal epithelial tumors is based on morphology and recognizes their distinct cytogenetic abnormalities. However, tumors with overlapping morphologic features can sometimes be encountered. We aim to further characterize renal cell carcinomas (RCC) with extensive clear cell changes and papillary architecture that are distinct from the previously described entity of clear cell papillary RCC (ccPRCC).
Design: We reviewed over 632 RCC cases diagnosed during the past 10 years at our institution and identified 15 cases that had extensive tubulo-papillary architecture lined exclusively with clear cells. Of these, 10 cases that morphologically fit ccPRCC were excluded. Two to five 1.0 mm cores of representative tissue was obtained from each case to construct a tissue microarray. A comprehensive analysis of standardized immunohistochemical (IHC) markers and fluorescence in-situ hybridization (FISH) for chromosomes 3, 7, 17, and Y were obtained.
Results: The patients included 2 African Americans and 3 Caucasians (age 25-72 yr, median 53 yr) with normal baseline creatinine (except in 1 case with ESRD). Compared to ccPRCC, these tumors were predominantly large (range 2.5 to 8.5 cm, median 5.5 cm) and had high pathologic stage (3 cases were pT3a) and high Fuhrman nuclear grade (G2-G4). Positive lymph nodes were present at time of surgery in 1 case. None of the cases showed recurrence (median follow up time 17 months). The tumors were negative for CK7 (100%), HMWCK (100%), PAX2 (80%), EMA (60%), TFE3 (100%), and cathepsin K (100%), and positive for racemase (100%), CD10 (100%), vimentin (60%), weak PAX8 (80%), GLUT-1 (40%), RCC (80%), and CAM5.2 (60%). Four cases showed polysomy 7, three cases showed polysomy 17, and four cases showed loss of chromosome Y. Deletion of 3p was not detected.
Conclusions: These tumors with papillary architecture and exclusive clear cell cytology show IHC and molecular profile similar to papillary RCC. Our study emphasizes the utility of IHC and molecular studies in making accurate diagnosis of renal cell tumors.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 82, Wednesday Morning


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