P03.010 Leukemia

Leukemia is a group of hematologic malignancies characterized by the abnormal proliferation of immature blood cells in the bone marrow. These abnormal cells crowd out healthy blood cell production, leading to deficiencies in red blood cells (anemia), white blood cells (increased risk of infection), and platelets (increased risk of bleeding). Understanding leukemia is crucial for the PLAB exam, as it’s a relatively common malignancy with diverse presentations.

Classification:

Leukemias are broadly classified into two main categories:

• Acute Leukemia: Rapidly progressing disease with immature blasts (precursor cells) dominating the bone marrow. Requires urgent treatment.
• Chronic Leukemia: Slower-growing disease with a higher proportion of mature or maturing abnormal white blood cells. May present with a more indolent course.

Further subtyping is based on the cell lineage involved:

• Myeloid Leukemia: Arises from myeloid precursors, giving rise to various types like acute myeloid leukemia (AML) and chronic myeloid leukemia (CML).
• Lymphoid Leukemia: Develops from lymphoid precursors, encompassing acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL).

Clinical Features:

The presenting signs and symptoms of leukemia can vary depending on the type and severity. Here’s a general overview:

• B-symptoms (common to both acute and chronic leukemia):
  • Fatigue
  • Weight loss
  • Fever
  • Night sweats
• Cytopenias (deficiencies in blood cells):
  • Anemia: Pallor, weakness, easy fatigue, shortness of breath.
  • Neutropenia (low white blood cells): Increased risk of infections, particularly bacterial and fungal.
  • Thrombocytopenia (low platelets): Easy bruising, bleeding from mucous membranes.
• Other: Bone pain, lymphadenopathy (swollen lymph nodes), hepatosplenomegaly (enlarged liver and spleen), neurological symptoms (in some cases).

Diagnosis:

A comprehensive workup is necessary to diagnose leukemia:

• Complete blood count (CBC): Identifies abnormalities in blood cell counts.
• Peripheral blood smear: Microscopic examination of blood cells to detect abnormal morphology.
• Bone marrow aspiration and biopsy: Definitive test for diagnosing leukemia, identifying the cell type, and assessing disease burden.
• Cytogenetic and molecular analysis: Provides information on specific genetic changes in the leukemic cells, which can influence prognosis and treatment decisions.

Points to Remember for the PLAB Exam:

• Recognize the common presenting features of leukemia, including B-symptoms and cytopenias.
• Differentiate between acute and chronic leukemia based on clinical course and cell morphology.
• Understand the importance of bone marrow examination for diagnosis and subtyping.
• Be familiar with the different types of leukemia (AML, ALL, CML, CLL) and their general management approaches (intensive chemotherapy for acute leukemia, chemotherapy or targeted therapies for chronic leukemia).
• Prognosis in leukemia varies depending on the type, age of the patient, and other factors.

Additional Resources:

• National Cancer Institute: https://www.cancer.gov/types/leukemia/hp
• American Cancer Society: https://www.cancer.org/cancer/types/leukemia.html
• British Committee for Standards in Haematology: https://b-s-h.org.uk/guidelines/guidelines