A 22 year old male with fatigue, recurrent fever, and enlarged cervical lymph nodes has numerous atypical lymphocytes in his peripheral blood smear. A biopsy from the patient's enlarged node shows expansion of lymphoid follicles with preservation of the underlying architecture. Numerous atypical lymphocytes are present in the paracoical areas. This patient most likely has ?

Infectious mononucleosis is a benign infection caused by the Epstein-Barr Virus (EBV), a herpesvirus. Although B lymphocytes are infected by the virus, the characteristic atypical cells are activated suppressor T cells - thus the paracoical location (T cell zone) in the lymph node. Lymph nodes in viral infections show expansion of germinal centers without loss of normal architecture. All lymphomas, including Burkitt's, Hodgkin's and non-Hodgkin's lymphomas, destroy the normal architecture of the lymph node. Burkitt's lymphoma produces a sea of monotonous, mitotically active cells in a "starry sky" appearance. Hodgkin's lymphoma also can show nodular or diffuse patterns, but is characterized by the presence of Reed-Sternberg cells. AIDS is associated with a number of neoplastic and infectious processes that may alter the lymph node structure. The characteristic lymph node changes in AIDS are progressive transformation of the germinal centers, not paracoical hyperplasia. Ref: Brooks G.F., Carroll K.C., Butel J.S., Morse S.A., Mietzner T.A. (2013). Chapter 33. Herpesviruses. In G.F. Brooks, K.C. Carroll, J.S. Butel, S.A. Morse, T.A. Mietzner (Eds), Jawetz, Melnick, & Adelberg's Medical Microbiology, 26e.