- 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)