Fei Yang, MD, FACMG, Kaiser Permanente Northwest
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General Disease Overview / Description of Cancer Category
T-lymphoblastic leukemia/lymphoma (T-cell ALL/LBL) constitute heterogeneous neoplastic lymphoid disorders characterized by the proliferation of immature (blast) cells of T-cell lineage. Cases with 25% or greater bone marrow involvement of lymphoid blasts have been designated acute lymphoblastic leukemia (T-ALL); while cases with tissue involvement (such as thymus, lymph node or extranodal sites including skin, tonsil, liver, spleen, central nervous system and testis in males) and less than 25% replacement of the bone marrow cellularity by lymphoid blasts have been designated as lymphoblastic lymphomas (T-LBL) .
T-ALL/LBL can occur at any age and have a bimodal age distribution, with a higher incidence peak in early childhood with median age of 10 years for T-ALL and a second lower incidence peak in older adults . In the Western countries, T-ALL accounts for about 15% of childhood ALL with slight male predominance and about 25% of adult ALL. T-LBL comprises about 85-90% of all lymphoblastic lymphomas . Patients with ataxia telangiectasia (AT) have increased risk of developing T-ALL .
There are two new entities under the 2016 version World Health Organization (WHO) classification: early T-precursor lymphoblastic leukemia (ETP T-ALL) and Natural killer (NK) cell lymphoblastic leukemia/lymphoma .
Chromosomal abnormalities are seen about 50-70% of cases of T-ALL/LBL. Rearrangements of T cell receptor (TCR) genes, involving alpha and delta (loci at 14q11), beta (locus at 7q35), and gamma (locus at 7p14-15) chain, are the most common recurrent aberrations. Other cytogenetics aberrations observed in T-ALL/LBL often involve transcription factors HOX11 (TLX1) (10q24) and HOX11L2 (TLX3) (5q35), occurring in 7% and 20% of childhood cases as well as in 30% and 10-15% of adult cases, respectively; and less frequently involve MYC (8q24.1), TAL1 (1p32), RBTN1 (LMO1) (11p15), RBTN2 (LMO2) (11p13) and LYL1 (19p13). Deletions of 9p resulting in loss of the tumor suppressor gene CDKN2A have been reported in about 30% of T-ALL. The molecular genetics of T-ALL are less well understood. Activation of the NOTCH1 signaling pathway occurs in about 50-80% of cases, but it is infrequent in ETP T-ALL. Other recurrently mutated genes are FBXW7, K-RAS, PTEN, and TP53, which may be associated with prognosis in adult T-ALL .
In childhood cases, T-ALL patients in general have poor outcome compared to B-ALL patients. The prognosis of T-ALL may be better than B-ALL in adult cases .
WHO Classification Pages (Includes Links to Content)
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- Borowitz MJ, et al., (2016).T-lymphoblastic leukemia/lymphoma, in World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4thedition.Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J, Vardiman JW, Editors. IARC Press: Lyon, France, p176-178.
- Choi JK, (2017).Precursor lymphoid neoplasms, in Hematopathology, A Volume in the Series: Foundations in Diagnostic Pathology, 3rd Edition. Hsi E, Editor. Elsevier, p467-481.
- Gatti R, Perlman S. Ataxia-Telangiectasia. 1999 Mar 19 [Updated 2016 Oct 27]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26468/
- Arber, Daniel A.; et al. (2016-05-19). "The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia". Blood. 127 (20): 2391–2405. doi:10.1182/blood-2016-03-643544. ISSN 1528-0020. PMID 27069254.
- Trinquand, Amélie; et al. (2013-12-01). "Toward a NOTCH1/FBXW7/RAS/PTEN-based oncogenetic risk classification of adult T-cell acute lymphoblastic leukemia: a Group for Research in Adult Acute Lymphoblastic Leukemia study". Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology. 31 (34): 4333–4342. doi:10.1200/JCO.2012.48.5292. ISSN 1527-7755. PMID 24166518.
- Stengel, Anna; et al. (2014-07-10). "TP53 mutations occur in 15.7% of ALL and are associated with MYC-rearrangement, low hypodiploidy, and a poor prognosis". Blood. 124 (2): 251–258. doi:10.1182/blood-2014-02-558833. ISSN 1528-0020. PMID 24829203.
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