Basophilia is an uncommon cause of leukocytosis. Basophils are inflammatory mediators of substances such as histamine. These cells, along with similar tissue-based cells (mast cells), have receptors for IgE and participate in the degranulation of white blood cells that occurs during allergic reactions, including anaphylaxis. Causes of basophilia, some of uncertain origin, are listed in Table 3.
|Table 4 - Etiology of Lymphocytosis|
|Absolute lymphocytosis |
Acute infections: cytomegalovirus infection, Epstein-Barr virus infection, pertussis, hepatitis, toxoplasmosis
Chronic infections: tuberculosis, brucellosis
Lymphoid malignancies: chronic lymphocytic leukemia
Normal in children less than 2 years of age
Acute phase of several viral illnesses
Connective tissue diseases
Splenomegaly with splenic sequestration
|Table 5 - Clinical Factors Increasing Suspicion of an Underlying Bone Marrow Disorder|
|Leukocytosis: white blood cell count greater than 30,000 per mm3 (30 X 109 per L)* |
Concurrent anemia or thrombocytopenia. Organ enlargement: liver, spleen or lymph nodes.
Life-threatening infection or immunosuppression.
Bleeding, bruising or petechiae Lethargy or significant weight loss
Leukocytosis with Primary Bone Marrow Disorders
Clinical factors that increase suspicion of an underlying bone marrow disorder are listed in Table 5. Bone marrow disorders are generally grouped into leukemias and myeloproliferative disorders.
Marrow abnormalities may occur with stem cells (acute leukemia) or more differentiated cells (chronic leukemia). Delineating acute leukemias from chronic leukemias is clinically important because the acute forms are more often associated with rapidly life-threatening complications such as bleeding, brain infarction and infection. Differences in the clinical presentations of acute and chronic leukemias are provided in Table 6.
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