Detection of Epstein-Barr virus in metastatic lymph nodes of patients with nasopharyngeal carcinoma and a primary unknown carcinoma.

BACKGROUND Nasopharyngeal carcinoma is often associated with neck lymph node (LN) metastases, which in many cases is the only manifestation of this disease. The submucosal and infiltrative characteristics of nasopharyngeal carcinoma make this type of cancer difficult to diagnose. Nasopharyngeal carcinoma has also been reported to be strongly associated with the Epstein-Barr virus. METHODS We examined 36 nasopharyngeal carcinomas (from 30 primary sites and from 6 metastasized LNs), 13 metastasized LNs of other head and neck cancers, and 12 primary unknown neck metastases using an in situ hybridization technique. RESULTS In the nasopharyngeal carcinomas, in situ hybridization with an Epstein-Barr virus-encoded small RNA identified the Epstein-Barr virus in 20 (67%) of the 30 primary sites and in 3 (50%) of the 6 metastasized LNs. Epstein-Barr virus was not detected in metastasized LNs of other head and neck cancers, but was detected in 1 of the primary unknown neck metastases. CONCLUSION In situ hybridization using a digoxigenin-labeled Epstein-Barr virus-encoded small RNA probe is useful for the differential diagnosis of metastasized LNs when the primary site is unknown.