BASALOID-SQUAMOUS CARCINOMA OF THE NASOPHARYNX - AN EPSTEIN-BARR VIRUS-ASSOCIATED NEOPLASM COMPARED WITH MORPHOLOGICALLY IDENTICAL TUMORS OCCURRING IN OTHER SITES

Background. Basaloid-squamous carcinoma is a newly characterized, high ly aggressive neoplasm occurring mostly in the base of tongue, hypopha rynx, larynx, and esophagus, Its occurrence in the nasopharynx is rare . Methods. The clinicopathologic features of three cases of basaloid-s quamous carcinoma of the nasopharynx are described and were studied fo r the presence of Epstein-Barr virus (EBV) by in situ hybridization fo r EBV-encoded small nuclear RNA (EBER). For comparison, basaloid-squam ous carcinomas occurring in other sites also were studied for the pres ence of EBV. Results. EBER was detected in all 3 cases of basaloid-squ amous carcinoma occurring in the nasopharynx, but in none of the 13 ca ses from other sites including the esophagus, larynx, pharynx, hypopha rynx, and nasal cavity, The nasopharyngeal basaloid-squamous carcinoma s occurred in two male and one female patients with an age range of 48 -70 years. The serum immunoglobulin A against the EBV-viral capsid ant igen was elevated in all three cases. Two patients developed cervical lymph node involvement during the course of the disease. All three pat ients were treated by radiotherapy and survived for longer than 34 mon ths compared with the average reported median survival of approximatel y 2 years for basaloid-squamous carcinomas occurring in the usual site s. Conclusion. Based on this limited study, basaloid-squamous carcinom a occurring in the nasopharynx appears to be an EBV-associated neoplas m, whereas the same tumor occurring in other sites is not, The prognos is is potentially better for patients with nasopharyngeal basaloid-squ amous carcinoma, which appears to be pathogenetically and biologically more related to the much more common nasopharyngeal undifferentiated carcinoma.