Study of Epithelial to Mesenchymal Transition in Atypical Fibroxanthoma and Undifferentiated Pleomorphic Sarcoma to Discern an Epithelial Origin.

Atypical fibroxanthoma (AFX) is considered a fibroblastic or myofibroblastic neoplasm probably corresponding to a superficial variant of undifferentiated pleomorphic sarcoma (UPS). However, an epithelial origin has also been postulated. An immunohistochemical study of the epithelial to mesenchymal transition (EMT) phenomenon was performed in a series of 19 AFX and 4 UPS to discern an epithelial origin. A panel of epithelial (cytokeratins AE1-AE3 panel, podoplanin D2-40, and E-cadherin) and EMT (vimentin, Twist, Zeb1, and Snail1) markers were evaluated in both tumoral cells and the adjacent epidermis. Podoplanin and Snail1 were negative in all the samples. Nuclear E-cadherin, Twist, and Zeb1 were detected in most lesions, as previously reported in other sarcomas. In the epidermis, E-cadherin showed a normal membranous pattern and only isolated cells were positive for vimentin. Twist and Zeb1 were mainly negative in the epidermis. None of the immunohistochemical markers mentioned above elicited a conspicuous bridging between the epidermis and the dermis. Our findings suggest that EMT does not play a role in the development of AFX or UPS.