Subtypes of acute lymphoblastic leukemia (ALL)

Acute lymphocytic leukemia can start in either B cells or T cells (lymphoblasts). The World Health Organization (WHO) classifies ALL by cell line (B cell or T cell) and by how mature the cell is (precursor or mature). There are 4 main subtypes of childhood ALL. Precursor B-cell ALL is further divided into subtypes.

World Health Organization (WHO) classification system

Cell line or subtype	Approximate % of cases
Precursor B-cell ALL Pro-B ALL Common B-cell ALL Pre-B ALL	80–85
Transitional pre-B ALL	Rare (3)
B cell	Rare (2–3)
T cell	13

The French-American-British (FAB) classification system is used along with the WHO classification, but not as a separate classification system.

French-American-British (FAB) classification system

FAB subtype	Approximate % of cases	Cell description
L1	90	small size regular shape small amount of cytoplasm
L2	10	large size nucleus has irregular shape moderate amount of cytoplasm
L3	Rare (1)	large size round shape cytoplasm overlies the nucleus

References

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