Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Pathology

Introduction Stromal invasion occurs when malignant epithelial cells extend beyond the myoepithelial cell layer and break through the basement membrane, thus myoepithelial cells markers are useful tool to discriminate between benign and / or non-invasive breast lesions from invasive breast cancer. DOG1 has been known to be a useful marker of gastrointestinal stromal tumors (GISTs), and was not widely studied before as MECs marker AIM OF THE WORK Aim of the study is to assess the immunohistochemical expression of DOG1 in various reactive, benign, and malignant breast lesions and to evaluate its use as a novel myoepithelial marker for discriminating between invasive breast carcinoma and noninvasive breast lesions. Results DOG1 reactivity in this study was 40 cases of different breast lesions with the following distribution 13 cases benign breast lesions in which there is 12 cases positive for DOG1 reaction 92.3% and one case DOG1 negative staining with 7.7%, 7 cases DCIS in which there is 6 cases positive for DOG1 reaction 85.7% and one case have negative DOG1 staining 14.3% and 20 cases invasive breast carcinoma (one is invasive lobular carcinoma and 19 are invasive duct carcinoma) all are negative to DOG1 staining 100%. With the following diagnostic accuracy; sensitivity of DOG 1 100%, its specificity 90%, PPV 90%, NPV 100% with over all Accuracy 95%. This means that DOG1 may be a tool for MECs Staining

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