T-lymphoblastic leukemia/lymphoma

T-lymphoblastic leukemia/lymphoma (WHO 2008),^[1]: 219 previously labeled precursor T-lymphoblastic leukemia/lymphoma (WHO 2001)^[1]: 219 is a form of lymphoid leukemia^[2][3] and lymphoma^[4] in which too many T-cell lymphoblasts (immature white blood cells) are found in the blood, bone marrow, and tissues, particularly mediastinal lymph nodes.^[1]: 635 Labeling as leukemia or lymphoma depends on which feature is more pronounced in a given situation, but has no biological or treatment implication.^[1]: 635

T-lymphoblastic leukemia/lymphoma
Other names	Precursor T-cell lymphoblastic lymphoma, Precursor T acute lymphoblastic leukemia/lymphoma
Specialty	Hematology, oncology

It is uncommon in adults, but represents 15% of childhood acute lymphoblastic leukemia and 90% of lymphoblastic lymphoma.^[1]: 635

The 2008 terminology dropped "precursor" to avoid linguistic redundancy because the lymphoblast is an immature precursor cell by definition.^[1]: 219