Sinonasal undifferentiated carcinoma, nasopharyngeal-type undifferentiated carcinoma and keratinizing and nonkeratinizing squamous cell carcinoma express different cytokeratin patterns - Franchi,A.; Moroni,M.; Massi,D.; Paglierani,M.; Santucci,M. (Am J Surg Pathol, 2002)