Histological and ultrastructural changes in experimentally produced post-vaccinial lymphadenitis in rabbits.

Light and Electron microscopic alterations in lymph nodes after intradermal vaccinia virus inoculation are described. In the early stages the lymph nodes show a diffuse lymphoreticular proliferation associated with the appearance of peculiar large cells called reticulolymphoblasts. This appearance can be mistaken for malignant lymphoma. Later on, these changes are replaced by markedly hypertrophied lymphoid follicles which persist for long periods. These alterations can be mistaken for follicular lymphoma. Evidence is presented that reticulolymphoblasts are derived from transformed lymphocytes.