Postvaccinial lymphadenitis.Hyperplasia of lymphoid tissue that simulates malignant lymphomas

Nine of 20 cases of postvaccinial lymphadenitis were submitted to the Armed Forces Institute of Pathology as representing a malignant lymphoma. Histologically these lymph nodes are characterized by: (1) an increased number of reticular lymphoblasts, imparting a mottled appearance to the lymphoid tissue; (2) a diffuse, follicular or combined diffuse and follicular hyperplasia; (3) vascular and sinusoidal changes; and (4) a mixed cellular response. The reticular lymphoblasts can be misconstrued as Reed-Sternberg cells. These cells have scant cytoplasm, a large nucleus and one or more acidophilic nudeoli. The histologic changes of these lymph nodes are not pathognomonic because similar changes occur in infectious mononucleosis, herpes zoster and dcrmatopathic lymphadenitis. Significantly, in 14 cases the history of vaccination was overlooked; in 13 cases the lymph node was removed from the left supra-clavicular region and in 12 cases the patient complained of a mass that caused pain.