Lymphocytosis
Increased numbers of lymphocytes in the blood may occur in infectious mononucleosis (mono), a self-limited viral infection common in young people, and acute infectious lymphocytosis, a benign self-limited viral disorder.
The Leukemias
Literally, a cancer of the white blood cells in which uncontrolled, increasing numbers of abnormal WBCs occur in blood forming and other tissues. Types of leukemia are identified by the dominant cell involved:
• Immature lymphocytes predominate in acute lymphocytic (or lymphoblastic) leukemias (ALL) and chronic lymphocytic leukemias (CLL)
• Myeloid cells predominate in acute myelocytic leukemia (AML)
• Granulocytes predominate in chronic myelocytic leukemia (CML)
CLL – Blood smear from an adult male with a marked lymphocytosis
Causes: Heredity, immune deficiencies, chronic marrow dysfunction, environmental factors (radiation, toxic chemicals), viruses.
Lymphomas
This group of neoplasms that arise in the reticuloendothelial system (RES) and lymphatic system include:
• Hodgkin‘s disease, a chronic disease involving the lymphatic system and a wide variety of changes in WBCs; eosinophilia may be present, and anemia may develop in advanced cases
• Malignant lymphomas and non-Hodgkin’s lymphomas
