OFP-08-010 Salivary duct carcinoma: Morphological and immunohistochemical study of 15 cases M. Vazmitel * , A. Dubrovskij, R. Smoljakova, S. Rjabceva * Minsk, Belarus Objective: An evaluation of morphological and imunohistochemical features of salivary duct carcinoma (SDC). Method: 15 cases SDC were retrieved from tumor archives collected at Belarusian Cancer Centre from 2002 to 2011 years. Immunohistochemistry, FISH. Results: A man to women ratio was 10:5; median age 61,5 years (average . Tumors arose in the parotid (n=13), submandibular (n=2) glands. SDC developed from pleomorphic adenoma (n=3) or de novo (n=12), there were foci of ductal carcinoma in situ (n=4), sialodochodysplasia (n=4) and Pagetoid spread (n=1) additionally to usual features of SDC. As well, tumors demonstrated acinic cell carcinoma-like (n = 2) and micropapillary growth patterns (n=1), oncocytic (n=4), clear cells (n=3), apocrine (n=1) and mucinous (n=1) changes. Immunohistochemically, tumors were characterized by AR-expression (n= 9), Her2/neu overexpression (n=7), of them score 2+ in 2 cases. CK8 and S-100 positivity, STAT5 negativity was detected in one case with acinic cell carcinoma-like pattern. Foci of SDC in situ were highlighted by CK14 and calponin. Amplification of c-erb2-gene was found in 1 case, ETV6/NTRK3 gene was not identified in acinic cell carcinoma-like SDC. Conclusion: Salivary duct carcinoma, like breast cancer, is characterized by wide variability of morphological patterns and immunohistochemical features reflecting possible molecular heterogeneity, which need further investigation. Sunday, 9 September 2012, 17.00-19. Objective: Quantification of protein expression based on immunohistochemistry (IHC) is an important step for translational research and clinical routine. However, routinely used eyeballing scoring systems are time-consuming and subject to significant intra-and interobserver variability. Aim of our study was to explore, whether an image analysis software proves sufficient as an alternative tool to assess protein expression. Method: 630 prostate cancer specimens were stained with one nucleus specific marker (i.e., ERG), one cytoplasmic specific marker (i.e., SLC45A3), and one marker expressed in both compartments (i.e., TMPRSS2). A pathologist visually quantified all stainings, applying a four-step scoring system. For digital quantification, an image analysis software (Tissue Studio v.2.1) obtained a continuous spectrum of staining intensity. Results: For each of the three antibodies we found a strong correlation of the eyeballing protein expression score and the score of the image analysis software (correlation coefficient of 0.94, 0.92, and 0.90 for ERG, SLC45A3, and TMPRSS2, respectively, p<0.01). Conclusion: Our data suggest that Tissue Studio is a powerful tool for the quantification of protein expression in IHC stainings. Further, since the digital analysis is precise, it might help to overcome intra-and interobserver variability and increase objectivity of IHC based protein assessment.