T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia
T-lymphoblastic cells of acute leukemia in the bone marrow. In some cases, the cytoplasm is concentrated at one pole of the cell, forming "hand mirror cells".
Specialty	Haematology, oncology
Symptoms	Recurrent infections, unusual or common bleeding and bruising, extreme tiredness, unexplained fever, unexplained weight gain, swollen lymph nodes
Usual onset	Most prevalent in the adult population with incidence diminishing with age. Amongst pediatric population, median onset of age 9. Marked male predominance [1]
Causes	Currently unknown
Diagnostic method	Blood test, bone marrow aspiration,[2] biopsy, CT, MRI, lumbar puncture,[2] genetic testing
Treatment	Long-term chemotherapy,[3] CNS radiation therapy,[1] stem cell transplantation [4]
Prognosis	5-Year Event Free Survival: 70%, Overall Survival: 80% [1]
Frequency	7% at ages 1-10, 14% at ages 10-15, and 29% at ages 15-18 [5]

T-cell acute lymphoblastic leukemia (T-ALL) is a type of acute lymphoblastic leukemia characterized by an aggressive malignant neoplasm of the bone marrow.^[6] Acute lymphoblastic leukemia (ALL) is a condition, wherein immature white blood cells accumulate in the bone marrow and crowd out normal white blood cells.^[7] Accumulation in the liver, spleen, and lymph nodes frequently occurs as well.^[8]

The two most common cells involved in ALL are B-lymphocytes and T-lymphocytes. B-lymphocytes protect the body against viruses and bacteria through antibody production, whereas T-lymphocytes destroy bacteria or cells infected with viruses.^[9] Approximately 20% of ALL patients suffer from T-ALL, which is more prevalent in the adult population compared to children, with incidence rates diminishing as the age of the patient increases.^[6][10]

Among T-ALL cases in the pediatric population, the median onset is age 9, and the disease is particularly prominent among adolescents.^[6] The disease arises when certain cytogenetic and molecular abnormalities result in the disruption of developmental pathways that control thymocyte development, tumour suppressor development, and alterations in the control of cell growth and proliferation become dysregulated.^[1]

Distinct from adult T-cell leukemia (in which T-cell lymphotropic virus Type I causes malignant maturation of T-cells), T-ALL is a precursor for lymphoid neoplasm.^[6] Its clinical presentation most commonly includes infiltration of the central nervous system (CNS, i.e. brain and spinal cord), and is often associated with a mediastinal mass that originates from the thymus, as well as extramedullary involvement of multiple organs (particularly lymph nodes) as a result of hyperleukocytosis.