Acute Leukemia WHO Classification Flashcards

Study Notes

Definition and Differentiation of Acute and Chronic Leukemias

Leukemia, lymphoma, and myeloma are malignant blood cell disorders.
Leukemias typically originate in the bone marrow; lymphomas originate in lymphoid tissues.
Leukemias commonly involve white blood cells; may also affect red blood cells and platelets.
Myelomas specifically involve plasma cells, lymphocytes that have responded to antigens.

Causes of Acute Leukemias: Triggers of Genetic Changes

Acute leukemia is a clonal disease caused by mutations in hematopoietic precursors.
Specific triggers for genetic changes are often unidentified but include:
- Environmental factors (e.g., radiation exposure).
- Chemical exposures (e.g., benzene, organic solvents).
- Immunosuppression (e.g., in organ transplant patients).
- Pre-existing genetic conditions (e.g., Down Syndrome, Fanconi's Anemia).
- Certain viruses related to chronic leukemias or lymphomas.
- Previous cancer treatments involving chemotherapy/radiation.

Types of Genetic Changes in Acute Leukemia

Acute leukemia displays various gene mutations and chromosomal abnormalities.
Genetic alterations typically include:
- Oncogenes: Cause neoplastic conditions, affecting DNA repair, immune response, and cell growth.
- Protooncogenes: Upregulate cell growth; mutations can lead to oncogenes.
- Tumor suppressor genes: Downregulate growth; alterations lead to unchecked proliferation.
Common chromosomal abnormalities observed:
- Translocations: Chromosomal pieces swap places; notable for the Philadelphia Chromosome linked to Chronic Myeloid Leukemia.
- Inversions: Chromosomal segments are reversed, altering gene expression.
- Deletions: Loss of chromosome segments; impacts tumor suppressor gene functions.
- Additions: Gaining chromosome segments or additional chromosomes, potentially leading to oncogene excess.

Occurrence and Frequency of Acute Leukemia

Lymphomas are more prevalent than acute leukemias.
Among acute leukemias, acute myeloid leukemia (AML) is more common than acute lymphoid leukemia (ALL).
AML predominantly affects adults; ALL is more prevalent in children.
Mixed phenotype acute leukemia (MPAL) is rare and can occur in both demographics.
Males exhibit a slightly higher incidence of leukemia compared to females in the US.
Despite rising incidence rates, mortality has decreased due to advancements in treatment and early detection.

Classification Systems

The French-American-British (FAB) system initially classified acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) based on cell staging and morphology.
The classification of blood disorders focuses on cellular characteristics identified through cytochemical staining.

Description

This set of flashcards focuses on the WHO classification of acute leukemias, distinguishing them from chronic leukemias. Learn essential definitions and understand the key differences and characteristics of these neoplastic blood cell disorders.