Histological and electron microscopic studies of endemic ethmoidal carcinomas in cattle.

In five cases of endemic ethmoidal carcinoma in cattle from the Dominican Republic three tumor types could be classified: undifferentiated carcinoma (3), adenocarcinoma (1), and squamous cell carcinoma (1). Electron microscopy showed that the tumor cells in undifferentiated carcinomas closely resembled the cells of the normal olfactory mucosa. This was especially true for the dark cells of Bowman's gland. Ultrastructurally, the lymphoid cells of the undifferentiated bovine carcinoma resembled the lymphoid cells of human nasopharyngeal carcinoma being closely associated with Epstein-Barr Virus. This and epidemiological observations suggested a viral cause of endemic ethmoidal carcinoma.