[832] Clear Cell-Papillary Renal Cell Carcinoma (CP-RCC) Not Associated with End Stage Renal Disease: Clinicopathologic Analysis of 50 Tumors Confirming a Novel Subtype of Renal Cell Carcinoma (RCC) Occurring in a Sporadic Setting.

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

Background: RCC with clear cell & papillary features includes numerous distinctive subtypes including a recently described subtype arising in end-stage kidneys. Accurate subtyping of RCC is essential as each represents a distinctive clinicopathologic entity associated with prognostic & predictive significance.
Design: A detailed clinicopathologic study of 50 tumors occurring in 48 patients was performed.
Results: The mean age of the pts. was 63 (range 32-83) yrs. with slight male predominance (1.3:1). All tumors were well circumscribed, averaged 2.2 (range 0.5-6) cm. Tumors had relatively typical morphology with encapsulation & tubular, tubulopapillary, tubulocystic & cystic morphology. The papillary architecture was unique in that it occurred secondarily within tubules and cysts, occasionally with branching. The cytoplasm was variable although all tumors had clear cytoplasm with distinct nuclear arrangement aligned circumferentially, resembling secretory endometrium. The nuclei of all cases were low grade, mostly Fuhrman nuclear grade 2 with only focal areas showing prominent nucleoli. Necrosis, mitotic activity, vascular invasion, or sarcomatoid change were not observed in any case. The stroma varied from being hyalanized to occasionally fibromuscular. 94% of tumors were pT1a & 6% were pT1b. Immunostudies showed CK7 (100%), HMCK (96%), PAX-2 (100%), PAX-8 (100%), vimentin (100%), CAIX (97%) positivity, & negativity for racemase, TFE3 & RCC Ag. Follow up in 25 pts.; mean 19 (range 1-91) mos. showed no evidence of local recurrence, distant metastasis or death due to disease.
Conclusions: 1) CP-RCC may occur in a sporadic setting and is distinctive from other unique subtypes of RCC. 2) The tumors are frequently small and invariably of low nuclear grade and low pathologic stage with extremely favorable prognosis. 3) Its distinctive immunoprofile has utility in the accurate distinction from other RCC with clear and papillary features.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 1:15 PM

Platform Session: Section A, Tuesday Afternoon


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