Lymphocytosis: Should i Panic?


A high lymphocyte count is usually found when your doctor has ordered tests to help diagnose a condition you’re already experiencing. It’s rarely an unexpected finding or simply discovered by chance. Talk with your doctor about what your test results mean. A high lymphocyte count and results from other tests may indicate the cause of your illness. Or your doctor may suggest other tests to further check your condition.

How to Approach to the child with lymphocytosis

Lymphocytes are a subset of white blood cells (WBC) that form an integral part of the immune system. They facilitate the body’s humoral and cellular immunity against foreign proteins and pathogens. An increase in circulating lymphocytes (lymphocytosis) can be seen following infections such as infectious mononucleosis and pertussis, or in lymphoproliferative disorders such as acute and chronic lymphocytic leukemia. A similar array of disorders can cause a decrease in lymphocyte counts (lymphocytopenia), although immunodeficiency states must also be considered, especially in infants and young children.

The various causes of lymphocytosis and lymphocytopenia in children will be reviewed here. Information on acute lymphoblastic leukemia (ALL), neutrophilia, neutropenia, and lymphocytosis/lymphocytopenia in adults is presented separately.