Undifferentiated nasopharyngeal carcinoma (lymphoepithelioma) is defined as a carcinoma with cytologically uniform cells with ovoid vesicular nuclei, prominent nucleoli, and indistinct cell borders resulting in a syncytial pattern. Usually, an inflammatory infiltrate rich in mature lymphocytes and occasionally eosinophiles is also present (Sternberg's Diagnostic Surgical Pathology, 3rd ed., 1999). --2002
