[788] Pax8, HIG- 2, KSP Cadherin and CA-IX Expression in Papillary RCC, Collecting Ducts RCC and MTSC

DE Baydar, L Schultz, PB Illei, R Albadine, R Sharma, S Abullazade, K Yildiz, GJ Netto. Johns Hopkins Univ, Baltimore; Hacettepe University, Ankara, Turkey

Background: Papillary renal cell carcinoma (PapRCC) displays variable morphology that may occasionally overlap with those of Mucinous Tubular & Spindle cell carcinoma (MTSC) in lower grade PapRCC and with those of Collecting Duct carcinoma (CDC) in high grade PapRCC. Here, we evaluated the expression of several novel renal markers in these three types of RCC including markers of renal differentiation [PAX8 and KSP-Cadherin (Kidney-specific Cadherin)] and markers of the hypoxia-induced pathway [HIG2 (hypoxia inducible gene 2) and CAIX (carbonic anhydrase IX)]. The findings were assessed for differences in expression pattern that could be of utility in the differential diagnosis.
Design: Standard immunohistochemical analysis for Pax8 (Protein tech group, Inc., USA), KSP-Cadherin (Cell Marque, USA), HIG2 (Novocastra, UK), and CAIX (Novocastra, UK) was performed on 45 PapRCC, 8 MTSC and 6 CDC tumors using routine formalin fixed paraffin embedded routine sections and TMA slides. For each marker, extent of staining was categorized as negative (<5%), focal (5-25%), multifocal (25-75%) or diffuse (>75%).
Results: AS illustrated in the table below, Pax8 and HIG2 were positive in all CDC and in the majority of PapRCC and MTSC. KSP-Cadherin showed similar expression in the three types of RCC (focal in 4/6 positive PapRCC, 1/1 MTSC and 1/1 CDC). CAIX was preferably expressed in MTSC (50%) with focal extent in all cases, while CAIX was positive in only 2/44 cases of PapRCC and focally in 1/6 CDC.

Immunoprofile of PapRCC,MTSC and CDC
PapRCC43/44 (96%)6/44 (14%)2/44 (5%)34/44 (77%)
MTSC7/8 (88%)1/8 (12%)4/8 (50%)7/8 (88%)
CDC6/6 (100%)1/6 (16%)1/6 (16%)6/6 (100%)
p valuep:NSp:NSp=0.001p:NS

Conclusions: CAIX was significantly more frequently expressed in MTSC compared to CDC and PapRCC. For the remaining tested markers, PapRCC, MTSC and CDC demonstrated an overall comparable immunohistochemical profile.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 134, Tuesday Morning


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