Lymphoepithelioma-like carcinoma of the lung.

Originally described in the nasopharynx, lymphoepitheliomas are undifferentiated carcinomas with prominent lymphoid infiltration. Recently this tumor has been described in a number of other sites. An association with prior infection by the Epstein-Barr virus has been recognized in cases from the nasopharynx. We report four cases of lymphoepithelioma-like carcinoma arising in the lung. Epstein-Barr virus serology indicated prior infection in two cases, one of which was also found by in situ hybridization to have the virus genome. Lymphoepithelioma-like carcinoma must be considered in the differential diagnosis of primary lung tumors, particularly when an extensive infiltrate by lymphoid tissue is present and may even suggest lymphoma.