Classification of leukemia?

Leukemia can be classified into four main types based on the type of white blood cell affected and the rate of progression of the disease:

1. Acute lymphoblastic leukemia (ALL): This type of leukemia affects lymphoid cells and progresses rapidly. It is most common in children, but can also occur in adults.

2. Acute myeloid leukemia (AML): AML affects myeloid cells and also progresses rapidly. It can occur in both children and adults.

3. Chronic lymphocytic leukemia (CLL): CLL affects lymphoid cells and progresses slowly. It is most common in older adults.

4. Chronic myeloid leukemia (CML): CML affects myeloid cells and progresses slowly. It can occur in both children and adults.

There are also other less common types of leukemia, such as hairy cell leukemia and large granular lymphocytic leukemia.

By Cell of Origin:

- Myeloid leukemia: Arising from myeloid progenitor cells
- Lymphoid leukemia: Arising from lymphoid progenitor cells

By Stage of Differentiation:

- Acute leukemia: Blasts (immature cells) make up more than 20% of bone marrow cells
- Chronic leukemia: Blasts make up less than 20% of bone marrow cells

By Lineage:

- Myeloid leukemia:
- Acute myeloid leukemia (AML)
- Chronic myeloid leukemia (CML)
- Lymphoid leukemia:
- Acute lymphoblastic leukemia (ALL)
- Chronic lymphocytic leukemia (CLL)
- Follicular lymphoma

By Cytogenetics:

- Specific chromosomal abnormalities:
- Philadelphia chromosome (t(9;22)), in CML
- Down syndrome, in some cases of AML
- Numerical abnormalities:
- Trisomy 8, in AML
- Deletion 5q, in myelodysplastic syndrome

By Immunophenotype:

- Surface marker expression:
- CD34+ in ALL
- CD19+, CD20+ in CLL
- CD33+ in AML

Other Classifications:

- Secondary leukemia: Occurring after exposure to certain toxins or radiation
- T-cell leukemia: Arising from T-lymphocytes
- B-cell leukemia: Arising from B-lymphocytes
- Hairy cell leukemia: A rare type of chronic lymphoid leukemia