[880] Immunohistochemical Study of Clear Cell Papillary Renal Cell Carcinoma.

Song Lu, Priti Lal, John E Tomaszewski, Zhanyong Bing. University of Pennsylvania, Philadelphia

Background: Clear cell papillary renal cell carcinoma (CCPRCC) is a recently described renal neoplasm that has morphologic features of both clear cell renal cell carcinoma and papillary renal cell carcinoma. Due to its rarity, the morphologic and immunohistochemical features of CCPRCC need to be further defined.
Design: Potential CCPRCC cases were identified by a natural language computer search for the diagnostic description of both “clear cell” and “papillary” over a 4-year period on pathology reports from kidney tumor specimens from the Department of Pathology in our hospital. H&E stained slides were reviewed. A panel of immunohistochemical stains with appropriate controls was performed, including RCC, CD10, vimentin, CK7, EMA, E-cadherin, TFE-3, CK903, and AMACR. Demographic data, clinical information, Fuhrman nuclear grade and tumor stage were correlated.
Results: 18 out of 236 renal cell carcinomas had diagnostic description of both clear cell morphology and papillary architectures during the 4-year period. Out of these 18 cases, one needle biopsy and four nephrectomy specimens were confirmed to be CCPRCC based on the histologic features described in the literature. Of these, one was male and four female, with age ranged from 38-68 years (mean 61).Three patients had end stage renal disease, while the others had kidneys with normal function. Tumor could arise in either the native or the transplanted kidney. Tumor size varied from 0.1 cm to 3.6 cm. Two patients had multiple tumor nodules involving either unilateral or bilateral kidneys, one patient had concurrent papillary renal cell carcinoma, and another patient had multiple renal papillary adenomas. Tumor could be either solid or predominantly cystic. The nuclei of clear cells lining the papillary architecture were either located towards the luminal side or in the center. Immunostains for CK7, EMA, CK903 and E-cadherin were positive in all the cases tested, while RCC was consistently negative. AMACR, CD10, vimentin and TFE-3 immunostains were variably positive. All tumors were of low Fuhrman nuclear grade (I or II), at low tumor stage (pT1a), and organ confined.
Conclusions: Although rare, CCPRCC is not that uncommon among renal tumors with both clear cell morphology and papillary architecture. It can arise in kidney of end stage disease as well as of normal function. Bilateral kidneys can be involved simultaneously, and other concurrent renal cell neoplasms can be seen as well. CCPRCC has distinct histologic and immunophenotypic characteristics that can be reliably employed to separate it from close mimickers.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 103, Monday Morning


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