[751] Relationship between Sporadic Clear Cell-Papillary Renal Cell Carcinoma (CP-RCC) and Renal Angiomyoadenomatous Tumor (RAT) of the Kidney: Analysis by Virtual-Karyotyping, Fluorescent In Situ Analysis and Immunohistochemistry (IHC).

Amir Behdad, Federico A Monzon, Ondrej Hes, Michelle Hirsch, Michal Michal, Eva Comperat, Philippe Camparo, Priya Rao, Maria Picken, Rudolfo Montironi, Chandrakanth Annaiah, Loren P Herrera, Komal Arora, Danielle E Westfall, Pheroze Tamboli, Mahul B Amin. Cedars-Sinai Medical Center, Los Angeles, CA; The Methodist Hospital, Houston, TX; Charles University, Plzen, Czech Republic; l'Hotel-Dieu, Place du Parvis, Paris, France; Hôpital Foch, Suresnes, France; Brigham and Women's Hospital, Boston, MA; MD Anderson Cancer Center, Houston, TX; Loyola University Hospital, Chicago, IL; Polytechnic University of the Marche Region, Ancona, Italy

Background: CP-RCC is a recently described (2006) unique subtype of renal cell carcinoma arising in the background of end-stage renal disease. Rare cases occurring sporadically have only recently been reported. RAT, a unique tumor composed of admixture of an epithelial clear cell component, and prominent leiomyomatous stroma, has also only recently (2009) been described. Both tumors display overlapping morphologic features including a distinct capsule, tubulopapillary architecture with luminal or mid-basally aligned nuclei resembling secretory endometrial glands with variable amount of clear cells. Papillae are seen secondarily within tubules and cysts occasionally with branching architecture. In addition, RAT has a conspicuous but still variable smooth muscle-rich stroma.
Design: We performed a detailed IHC (n=23) and molecular (n=6) profiling to understand the relationship between the two tumor types. We performed virtual karyotyping with SNP microarrys in representative samples of each tumor type to assess for chromosomal copy number imbalances. In addition, we performed 3p LOH, FISH for chromosomes 7, 17 and Y, and VHL mutation analyses.
Results: Both RAT (n=3) and CP-RCC (n=20) demonstrated identical immunoprofile: all tumors in both categories were positive for CK7, HMCK, PAX-2, PAX-8 and CAIX and negative for racemase and RCC. Neither tumor type showed any recurrent chromosomal imbalances by virtual karyotyping (n=3 each), FISH (n=10 CP-RCC, n=2 RAT) or 3p LOH (n=10 CP-RCC, n=2 RAT). Most tumors showed a normal diploid chromosomal complement. Only 3 CP-RCC tumors showed mutations in the VHL gene.
Conclusions: Both CP-RCC and RAT have identical morphologic features when the smooth muscle stroma of the latter is discounted. Similarities at the IHC and molecular levels further strengthen their interrelationship. Our analyses indicate that CP-RCC and RAT might be in the spectrum of the same category of tumors.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 87, Wednesday Morning


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