WBC DISORDERS

Infectious Mononucleosis ("Mono")

  • Definition: A self-limiting lymphoproliferative disorder.

  • Infection of: B lymphocytes.

  • Caused by: Epstein-Barr virus (EBV).

  • Prevalence: Most common in adolescents and young adults.

  • Transmission: Primarily through EBV-contaminated saliva.

  • Pathogenesis: Characterized by the proliferation of atypical lymphocytes.

  • Onset: Typically insidious, with an incubation period of 4-8 weeks.

Clinical Manifestations of Infectious Mononucleosis

  • Symptoms: Lymphadenopathy, hepatitis, splenomegaly.

  • Laboratory Findings:
      - WBC count increased (approximately 12,000 - 18,000 cells/mm³);
      - 95% of WBCs are lymphocytes.

  • Acute Phase Duration: 2-3 weeks.

  • Debility/Lethargy: May persist for 2-3 months.

  • Treatment: Symptomatic and supportive care.

Myelodysplastic Syndrome

  • Definition: A group of related hematologic disorders characterized by changes in the quantity and quality of bone marrow elements.

  • Demographics: Primarily affects elderly individuals (age > 65).

  • Clinical Manifestations: Cytopenias, which can include:
      - Anemia,
      - Increased risk of infection,
      - Spontaneous bleeding or easy bruising.

  • Etiology: Unknown; potential environmental triggers.

Diagnostics for Myelodysplastic Syndrome

  • Requires laboratory evaluation and bone marrow biopsy.

Treatment Options

  • Depends on disease severity, potential treatments include:
      - Supportive care,
      - Granulocyte colony-stimulating factor (G-CSF),
      - Erythropoietin,
      - Chemotherapy,
      - Bone marrow transplant.

Leukemias

  • Definition: A class of malignant neoplasms derived from a single hematopoietic cell line.

  • Characteristics of Leukemic Cells:
      - Immature and unregulated (undifferentiated).
      - Proliferate within the bone marrow, circulate in blood, and infiltrate spleen and lymph nodes.

  • Demographics: Affects both children and adults.

Classification of Leukemias

  • Classifications based on predominant cell type and the condition's acute or chronic nature:
      - Acute Lymphocytic Leukemia (ALL):
        - Most common leukemia in children.
      - Chronic Lymphocytic Leukemia (CLL):
        - Most prevalent leukemia in older adults.
      - Acute Myelocytic Leukemia (AML):
        - Primarily affects adults.
      - Chronic Myelocytic Leukemia (CML):
        - Can affect adults and children.

Leukemia Pathogenesis

  • Causes: Unknown, but increased exposure to radiation noted as a possible risk.

  • Characteristics of Leukemic Cells:
      - Immature type of WBC that proliferates rapidly and has a prolonged lifespan.
      - Cannot perform functions of mature leukocytes, rendering them ineffective as phagocytes.
      - Interfere with the maturation of normal bone marrow cells affecting RBCs and platelets.

Acute Leukemia

  • Onset: Sudden and stormy.

  • Symptoms: Related to decreased levels of mature WBCs, RBCs, & platelets.

  • ALL: Constitutes about 80% of childhood acute leukemias.

  • AML: Predominantly an adult disease.

  • Diagnosis: Blood and bone marrow tissue demonstrate immature WBCs (blasts) which may comprise 60-100% of cells.

Chronic Leukemia

  • Onset: More insidious.

  • Discovery: Often found during routine medical exams through blood counts.

  • CLL: Common in older adults, characterized by relatively mature but immunologically incompetent lymphocytes.

  • CML: Affecting adults and children, characterized by leukocytosis with immature cell types.

Treatment of Leukemias

  • Goal: Achieve remission.

  • Options:
      - Cytotoxic chemotherapy.
      - Stem Cell Transplant:
        - Allogeneic (from a volunteer donor),
        - Syngeneic (from an identical twin),
        - Autologous (from the patient’s own cells).

  • Risks: Infection, rejection, relapse of the disease.

Malignant Lymphomas

  • Definition: Neoplasms of cells derived from lymphoid tissue.

  • Types:
      - Hodgkin Disease
      - Non-Hodgkin Disease

Hodgkin Disease

  • Characteristics: Painless, progressive, rubbery enlargement of a single node or a group of nodes, often located in the neck area.

  • Reed-Sternberg Cell: Distinctive tumor cell identified in lymph node biopsies.

  • Diagnostics:
      - Peripheral blood analysis (abnormal CBC).
      - Lymph node biopsy.
      - Bone marrow examination.
      - Radiographic evaluation (CT, MRI, PET).

  • Etiology: Unknown; potential interacting factors include Epstein-Barr Virus, genetic predisposition, and exposure to toxins.

Clinical Manifestations of Hodgkin Disease

  • Insidious onset with painless enlarged lymph nodes and nonspecific symptoms.

Treatment Options

  • Chemotherapy.

  • Radiation.

  • Stem Cell Transplant.

  • Prognosis: Generally good since the condition typically spreads slowly and in a predictable pattern.

Non-Hodgkin Disease

  • Definition: Another neoplastic disorder of the lymphoid tissue.

  • Characteristics: Tends to spread early and can involve the liver, spleen, and bone marrow.

  • Clinical Presentation: Also characterized by painless, superficial lymphadenopathy and possible extranodal symptoms.

  • Etiology: Unknown; most patients have widely spread disease at diagnosis.

Clinical Manifestations of Non-Hodgkin Disease

  • Similar to Hodgkin lymphoma with painless lymph node enlargement and nonspecific symptoms.

Diagnosis and Treatment

  • Diagnostic methods similar to those for Hodgkin lymphoma, but with increased incidences of extranodal sites.

  • Treatment Options:
      - Chemotherapy.
      - Radiation.
      - For refractory cases: stem cell transplant.
      - Biological drug therapy.

  • Prognosis: Generally poorer compared to Hodgkin disease due to rapid and unpredictable spread.

Lymphadenopathy

  • Definitions: Enlargement of lymph nodes.

  • Locations:
      - Cervical nodes.
      - Axillary nodes.
      - Inguinal nodes.
      - Other lymphatic vessels.

  • Cervical Lymphadenopathy: Specific mention regarding the neck region's lymph nodes.

Multiple Myeloma

  • Definition: A type of plasma cell cancer affecting B cells.

  • Characteristics: Atypical proliferation of one type of immunoglobulin, referred to as “M protein” (a monoclonal antibody).

  • Pathophysiology: Malignant cells invade bone leading to increased osteoclast activity that results in bone destruction/resorption.

  • Impact on the Body: Results in impaired humoral immunity.

  • Clinical Manifestations:
      - Bone pain and fractures.
      - Symptoms related to impaired production of RBCs and WBCs.

  • Demographics: Men affected twice as often as women, average age at diagnosis is 65 years, more prevalent in African Americans compared to Whites.

  • Etiology: Unknown.

Clinical Features (CM) of Multiple Myeloma

  • Symptoms often present slowly and insidiously include:
      - Skeletal pain.
      - Hypercalcemia.

Diagnostics for Multiple Myeloma

  • Laboratory findings:
      - Presence of monoclonal antibody protein in serum and urine.
      - Pancytopenia.
      - Hypercalcemia.
      - Presence of Bence Jones proteins in urine.
      - Elevated serum creatinine levels.
      - X-rays showing osteolytic lesions.

Treatment Options for Multiple Myeloma

  • Monitoring.

  • Corticosteroids.

  • Chemotherapy.

  • Biological therapy.

  • Stem cell transplant.

  • Bisphosphonates.

  • Importance of adequate hydration is emphasized.

References