6.2 Lecture - Leukocytes and Leukocytosis

• Leukocytes include granulocytes, monocytes, and lymphocytes.
• Leukocyte disorders are categorized as quantitative or qualitative.
• Quantitative disorders involve the number of leukocytes
• Qualitative disorders involve leukocyte function.

Leukocytosis

• Leukocytosis denotes a higher-than-normal leukocyte count.
• It is a normal protective response to stressors.
• Stressors can include infection, exercise, or emotional changes.
• Leukemia is never a normal condition.
• It can be caused by radiation, anaphylactic shock, autoimmune disease, or certain drugs.

Granulocytosis

• Granulocytosis involves an increase in granulocytes released from the bone marrow.

Shift to the Left (Leftward Shift)

• Shift to the left occurs when the demand for mature neutrophils exceeds the supply.
• The bone marrow releases immature neutrophils.

Eosinophilia

• Eosinophilia is an increase in the number of circulating eosinophils.
• It is associated with allergic disorders like asthma and parasitic infections.

Monocytosis

• Monocytosis represents an increase in circulating monocytes.
• It is commonly associated with bacterial infections.

Lymphocytosis

• Lymphocytosis refers to an increase in lymphocytes
• It often occurs in acute viral infections.

Infectious Mononucleosis

• Infectious mononucleosis is a benign, self-limiting syndrome.
• It is caused by acute viral infection of B lymphocytes with EBV, a herpes virus.
• Transmission is usually through saliva, hence the name "kissing disease".

Leukemia

• Leukemia is a disorder of leukocytes in the bone marrow and blood.
• It involves uncontrolled proliferation of malignant leukocytes.
• There is a decreased production and function of normal hematopoietic cells.
• Acute leukemia has undifferentiated or immature cells and rapid onset.
• Chronic leukemia has more differentiated cells but impaired function and slow progression.
• Acute leukemias include Acute Lymphocytic Leukemia (ALL) and Acute Myelogenous Leukemia (AML).
• Chronic leukemias include Chronic Myelogenous Leukemia (CML) and Chronic Lymphocytic Leukemia (CLL).
• CLL is rare in individuals under 45 and more common between 50 and 70 years old.
• Chronic leukemias have a longer life expectancy.
• There is a statistical tendency for leukemia to reappear in families.
• Increased risk in adults is associated with exposure to cigarette smoke, benzene, and ionizing radiation.

Lymphadenopathy

• Lymphadenopathy is caused by an increase in size and number of germinal centers of the lymph nodes.
• Localized lymphadenopathy usually indicates drainage of an area with inflammation or infection.
• Generalized lymphadenopathy usually results from a malignant or non-malignant disease.

Lymphomas

• Lymphomas develop from proliferation of malignant lymphocytes in the lymphoid system.
• Hodgkin lymphoma and non-Hodgkin lymphoma occur in children and adults.
• Treatment and prognosis depend on the stage and type of lymphoma.
• The rate of non-Hodgkin's lymphoma has doubled since the 1970s.
• This increase in the number of cases is possibly due to immune deficiencies, including AIDS and organ transplants

Hodgkin Lymphoma

• Classic Hodgkin lymphoma is derived from a B cell that has not undergone successful immunoglobulin gene rearrangement.
• Survival of the cell may be linked to EBV infection.
• Clinical manifestations include fever, weight loss, night sweats, fatigue, and large, painless neck nodes.
• Early detection is difficult, and early lymphadenopathy can progress undetected for years.
• Survival rate depends on early detection.

Non-Hodgkin Lymphoma

• Non-Hodgkin lymphoma features progressive clonal expansion of B cells, T cells, and/or NK cells.
• Lymphomas originate from mutations in cellular genes, possibly environmentally induced.
• Successful treatment depends on the type and stage of lymphoma, cell type, and other factors.
• Overall survival rate is less than Hodgkin lymphoma.

Burkitt Lymphoma

• Burkitt lymphoma is a highly aggressive B-cell non-Hodgkin lymphoma.
• It accounts for 30% of childhood lymphomas worldwide.
• EBV is associated with almost all cases.
• Tumors in the jaw and facial bones are indicative of lymphoma.

Lymphoblastic Lymphoma

• Lymphoblastic lymphoma is a rare variant of non-Hodgkin lymphoma.
• It accounts for 20% of cases in children and adolescents.
• The T-cell variant is associated with a mediastinum mass.
• It results in chest pain and may cause compression of bronchi or the superior vena cava.

Conditions Mimicking Lymphomas

• Important distinction between lymphomas and other conditions is localized lymphadenopathy.

Multiple Myeloma

• Multiple myeloma is a biologically complex disease with wide range of genetic alterations.
• It has a poor prognosis.
• Median survival is three years.

Spleen Functions

• The spleen's relationship to the immune and hematologic systems was identified in the 18th century.

Splenomegaly

• Splenomegaly without a specific etiology is seen in 7-15% of individuals.

Overactive Spleen

• An overactive spleen results in hematologic alterations, reducing circulating blood cells.
• The spleen can sequester up to 50% of the red blood cell population, potentially leading to anemia.
• Splenectomy is a treatment option but not always the best choice.
• Individuals can lead normal lives after splenectomy, but hematologic abnormalities often exist.

Leukocytes include granulocytes, monocytes, and lymphocytes. Leukocytosis denotes a higher-than-normal leukocyte count, which is a normal protective response to stressors such as infection, exercise, or emotional changes. Leukemia is never a normal condition.