Epithelial-myoepithelial carcinoma ex pleomorphic adenoma in breast : An exotic rarity

Abstract

Similarities in the embryogenesis of breast and salivary gland and the dual epithelial myoepithelial cell differentiation in both anatomical sites account for the occurrence of salivary gland-type neoplasm in the breast [1]. Pleomorphic adenoma (PA) is one such benign neoplasm that occurs in both salivary gland and breast. In salivary gland, malignant transformation of PA is a well-recognized, albeit relatively, uncommon event. Malignant transformation can take the form of superimposed adenocarcinoma or development of a malignant mixed tumour with dual epithelial and mesenchymal elements [2]. PA, also known as benign mixed tumour, accounts for 45 to 74% of all major and minor salivary gland tumours and has been reported in other, less common sites such as the paranasal sinuses, larynx, palate, nasal septum, skin and breast [3, 4], It occurs less frequently in the human breast. Since the first case report by Lecene [4] in 1906, 68 cases of PA of the human breast have been documented in the world literature [5]. Malignant PA has been reported to occur outside of the major salivary glands but its occurrence in breast is rare. There are only three such case reports in English language literature [1]. However, there is no case of epithelial-myoepithelial carcinoma on a PA of breast reported. We describe a case of epithelial-myoepithelial carcinoma ex pleomorphic adenoma of breast diagnosed and managed at our hospital.