Figure 21-1 PROMINENT MONONUCLEAR LYMPHOCYTOSIS IN MONONUCLEOSIS.

Low power (A) illustrates the leukocytosis, mainly due to activated lymphocytes (B and C), which are contrasted with a normal small lymphocyte (D) and a monocyte and granulocyte (E). The large reactive lymphocytes are frequently confused with monocytes because of their morphologic resemblance and the term mononucleosis. Monocytes usually have a finer, lacy chromatin and a gray cytoplasm with small granules and vacuoles when compared with the large activated lymphocytes.

Figure 21-2 INFECTIOUS LIFE CYCLE OF EPSTEIN-BARR VIRUS.

Table 21-1 Frequently Determined EBV-Specific Antibodies

Modified from Schooley RT: Epstein-Barr virus (infectious mononucleosis). In Mandell GL, Bennett JE, Dolin R, editors: Principles and practice of infectious diseases, Philadelphia, 2000, Churchill Livingstone, p 1599.

Table 21-2 Clinical Manifestations of Infectious Mononucleosis

Modified from Schooley RT: Epstein-Barr virus (infectious mononucleosis). In Mandell GL, Bennett JE, Dolin R, editors: Principles and practice of infectious diseases, Philadelphia, 2000, Churchill Livingstone, p 1599.

Figure 21-3 PERIPHERAL BLOOD SMEAR IN INFECTIOUS MONONUCLEOSIS.

Low power (A) shows moderately high white blood cell count and high number of reactive, or “atypical” lymphocytes. Higher power (B to G) illustrates spectrum of lymphoid morphology, including small resting lymphocyte (B) for comparison, large granular lymphocyte (C), atypical forms (D to F), also referred to as “reactive” lymphs, and circulating plasma cell (G).

Figure 21-4 RUPTURED SPLEEN FROM PATIENT WITH INFECTIOUS MONONUCLEOSIS.

Sections from the spleen show increased white cells in the red pulp (A and B). These correspond to the proliferating activated lymphocytes seen in the blood. The lymphocytes can infiltrate into the splenic trabeculae (C), weakening the integrity of the spleen and making it more prone to rupture.

Table 21-3 Classification of Chronic Active EBV Infection