Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 35 3-4 1997 12 15 90 94 G. Irvanlou F. Mahjoub 2015 09 28 A 41 year old woman was referred to our center because of a left breast mass lesion of about two months duration. Routine pathologic examination of the mass revealed a .neoplastic tissue composed of large ovoid cells with clear cytoplasm arranged in broad sheets that were separated by thin bundles of connective tissue. Immunohistochemically tumor cells express smooth muscle actin, cytokeratin, and SI00 protein. Also two axillary lymph nodes were positive for tumor involvement, hence the name malignant myoepithelioma was applied for definition. Because of rarity of this type of tumor and paucity of the reported cases worltlwide, it appears to he an interesting case report. https://acta.tums.ac.ir/index.php/acta/article/view/1728 https://acta.tums.ac.ir/index.php/acta/article/download/1728/1721