T-cell acute lymphoblastic leukemia

Overview
T-cell acute lymphoblastic leukemia (T-ALL) is a type of acute lymphoblastic leukemia (ALL), a cancer of the lymphocyte-forming cells called lymphoblasts.

Presentation
About 13% to 15% of children with ALL have T-cell ALL. This type of leukemia affects boys more than girls, and generally affects children at an older age than B-cell ALL does. It is often associated with an enlarged thymus (which can sometimes cause breathing difficulty) and with early spread to the cerebrospinal fluid (the fluid that surrounds the brain and spinal cord).

Pathophysiology
T cells help protect us against foreign substances (those not normally present in the body). They recognize specific chemicals, such as those found on the outside of virus-infected cells. They then destroy these cells by releasing substances that cause them to develop holes and become leaky. T cells can also release substances called cytokines that attract other types of white blood cells, such as macrophages, which then surround and digest the infected cells.

Diagnosis
Normal B cells and T cells can be recognized by laboratory tests that identify distinctive chemicals on their surfaces. Some chemical substances are found only on B cells, and others are found only on T cells.

Causes
T-ALL is believed to be caused by a defect in the Notch signaling pathway.