In the former FAB classification, ALL was divided into three types based on cell size, prominence of nucleoli, and amount and appearance of cytoplasm:
- L1 (found mostly in children)
- L2 (found mostly in older children and adults)
- L3 (associated with Burkitt's Lymphoma)
The image to the right is a smear from a bone marrow that was diagnosed as ALL L1, often seen in children. Notice the consistently sized lymphoblasts with scant cytoplasm.