[795] Comparison of Immunohistochemical Profiles of Papillary Renal Cell Carcinoma Subtypes

Ahmed Alomari, Harriet Kluger, Kenneth Haines, Dinesh Singh, Manju L Prasad, Adebowale J Adeniran. Yale School of Medicine, New Haven, CT

Background: Papillary renal cell carcinoma (PRCC) is characterized morphologically by the presence of fibrovascular cores, lined by papillae of malignant epithelial cells. It is further sub-classified into 2 types based on cell type. Type 2 tumors are generally believed to have a poorer prognosis than type 1 tumors. This prognostic difference has led some to believe that some of the type 2 tumors may actually represent a separate entity from PRCC. This study was designed to compare the immunohistochemical profiles in both subtypes of PRCC.
Design: A tissue microarray block with 124 cases of PRCC was constructed. The tumors were stained with the following diagnostic antibodies: CK7, EMA, CD10, CAIX, vimentin, CK903, C-kit, racemase, PAX-8, PAX-2 and CEA. A stain was deemed to be positive if it demonstrated at least weak intensity in at least 10% of the tumor cells. Intensity was scored as 1+, 2+ and 3+ for weak, moderate and strong intensity, respectively. A score of 0 was given for negative staining.
Results: Results of the immunohistochemical stains are listed in Table 1.

Table 1: Results of Immunohistochemical Stains
 Type 1Type 2Mixed

The best immunohistochemical profile for both subtypes is: CK7: positive, EMA: positive, racemase: positive, PAX-8: positive, CD10: variable, PAX-2: variable, CAIX: negative, vimentin: negative and CK903: negative. There was no correlation between the staining pattern and tumor characteristics such as tumor type, location, nuclear grade, and presence of desmoplasia.
Conclusions: The immunohistochemical profiles of both types 1 and 2 PRCC are essentially the same. There is no prognostic significance to any of the immunostains. The similar immunohistochemical profile confirms that PRCC is one entity with divergent histologic features. The 2 subtypes can only be differentiated based purely on morphologic features.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 174, Monday Afternoon


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