Non-lymphoid tissue lesions induced by or associated with herpesvirus.

The members of herpesvirus group are variable in their effects on tissues of the human body. This results in a wide variety of clinical diseases and syndromes. Some produce impressive pathological lesions. Those produced by the viruses with tropism for ectodermally derived cells include herpes simplex virus and varicella zoster virus are well recognized by practically all medical specialists and even by those who are not medically oriented. Cytomegalovirus has tropism for epithelial cells that are ectodermally derived. Epstein-Barr virus (EBV) and human lymphotropic virus induce profound changes in the proliferative capabilities of lymphoid tissues. The non-lymphoid lesions induced by EBV are unique and fascinating. Leading the list is nasopharyngeal carcinoma (NPC), not all of which seem related to EBV. Only the non-keratinizing NPC has a convincing relationship to the virus. Other unusual lesions with suggested association with EBV are salivary glands tumors (benign and malignant) and undifferentiated thymic carcinomas. Both malignant lymphoepithelial lesions (anaplastic carcinoma) of salivary glands and anaplastic carcinoma of the thymus have microscopic similarity to undifferentiated NPC.