T-lymphoblastic leukemia/lymphoma (WHO 2008), previously labeled precursor T-lymphoblastic leukemia/lymphoma (WHO 2001) is a form of

lymphoid leukemia Lymphoid leukemias are a group of leukemias affecting circulating lymphocytes, a type of white blood cell. The lymphocytic leukemias are closely related to lymphomas of the lymphocytes, to the point that some of them are unitary disease entities t ...

and

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enla ...

in which too many

T-cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

lymphoblasts __NOTOC__ A lymphoblast is a modified naive lymphocyte with altered cell morphology. It occurs when the lymphocyte is activated by an antigen (from antigen-presenting cells) and increased in volume by nucleus and cytoplasm growth as well as new mRN ...

(immature

white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

) are found in the

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

, bone marrow, and tissues, particularly mediastinal lymph nodes. Labeling as

leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...

depends on which feature is more pronounced in a given situation, but has no biological or treatment implication. It is uncommon in adults, but represents 15% of childhood acute lymphoblastic leukemia and 90% of lymphoblastic lymphoma. The 2008 terminology dropped "precursor" to avoid linguistic redundancy because the

lymphoblast __NOTOC__ A lymphoblast is a modified naive lymphocyte with altered cell morphology. It occurs when the lymphocyte is activated by an antigen (from antigen-presenting cells) and increased in volume by nucleus and cytoplasm growth as well as new mRN ...

is an immature precursor cell by definition.

References

External links

Precursor T-lymphoblastic leukemia
entry in the public domain NCI Dictionary of Cancer Terms Acute lymphocytic leukemia Lymphoma {{Oncology-stub