Epithelial-myoepithelial tumour of the lung: a case report referring to its molecular histogenesis

We present the case of a 76 year-old woman with no interesting pathological history, to whom a pulmonary nodule is detected during a study of unknown origin neutropenia. An upper right lobectomy is performed.After macro and microscopic study, the diagnosis of pulmonary epithelial-myoepithelial tumour is made. It is a low malignant potential tumour with capacity to locally recur and less frequently to metastasize. Our case has the peculiarity of not being connected neither to visceral pleura nor to bronchial tree; we have not found this characteristic in any literature reviewed case.These tumours have been named in a lot of different ways, including adenomyoepithelioma, epithelial-myoepithelial tumour, epithelial-myoepithelial carcinoma or epithelial-myoepithelial tumour of uncertain malignant potential.The p27/kip-1 protein plays a fundamental role in the development of these neoplasms. As we have verified in our case, its aberrant cytoplasmic location, besides its proved oncogenic function, would favour the proliferation of stem cells, which would explain both dual phenotype with presence of myoepithelial cells without connection with the bronchial tree, and TTF-1 immunostaining in epithelial cells.Epithelial-myoepithelial tumours are rare neoplasms that occur more frequently in salivary glands, where they represent approximately 1% of primary tumours. In this location, they are considered as low malignant potential tumours with capacity to locally recur and less frequently to metastasize; that is why they are known as epithelial-myoepithelial carcinoma. Other sites where these neoplasms can arise are breast and skin.We present the case of a 76 year-old woman with an asymptomatic mass in the upper lobe of her right lung, which was diagnosed as epithelial-myoepithelial tumour.Myoepithelial cells play a fundamental role in the development of this kind of tumours. A subcellular aberrant location of p27/kip-1 inside myoepithelial cells would provoke loss of their growt