Marrow involvement common (85% have paratrabecular lymphoid aggregates); with marrow involvement, 40% have tumor cells in blood, which may resemble CLL 10% have peripheral lymphocytosis … These may be memory B cells, circulating after initial stimulation In rare cases, can see pronounced peripheral blood B lymphocytosis (often secondary to infection), with … Lymphocytosis, reflecting blood involvement, may also be present.
Lymphocytosis, along with greater than 10% atypical lymphocytes and mild thrombocytopenia, can be found in mononucleosis. … Results consistent with the diagnosis Peripheral white blood cell (WBC) count with differential: expect neutrophil predominance for strep throat and lymphocytosis for mononucelosis … However, infectious mononucleosis is more common in persons 10 to 30 years of age and is associated with fatigue, posterior cervical adenopathy, and atypical lymphocytosis
Blood smear may reveal lymphocytosis. … Blood work usually reveals presence of lymphocytosis and the diagnosis is confirmed with the Monospot test. … Lymphocytosis and thrombocytopenia alone are not confirmative for infectious mononucleosis because such a finding can be seen with many other noninfectious causes (malignancies