Leukemia - Acute
Other ALL
T cell acute lymphoblastic leukemia / lymphoma

Topic Completed: 1 March 2013

Revised: 17 September 2019

Copyright: (c) 2001-2018, PathologyOutlines.com, Inc.

PubMed Search: T cell acute lymphoblastic leukemia / lymphoma [title]

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Cite this page: Mihova D. T cell acute lymphoblastic leukemia (T ALL) / lymphoma (T LBL, T lymphoblastic leukemia / lymphoma). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/leukemiaTall.html. Accessed October 15th, 2019.
Definition / general
  • Neoplasm of T lineage lymphoblasts which may form lymphomatous masses, involve blood and bone marrow (Stanford School of Medicine: Precursor T Lymphoblastic Leukemia / Lymphoma [Accessed 13 April 2018])
  • Also called pre T cell acute lymphocytic leukemia / lymphoma (preT ALL), T lymphoblastic leukemia / lymphoma (T LBL)
  • See also Lymphoma and plasma cell neoplasms chapter
  • Teens and young men (older than B ALL)
  • Most cases begin after birth (Blood 2007;110:3036)
  • T ALL versus T LBL: T ALL has more immature phenotype, CD47 expression, no 11q23 rearrangement (Pediatr Blood Cancer 2006;47:130), different gene expression profile and may derive from T cell progenitor of bone marrow; T LBL is derived from thymocytes (Leuk Lymphoma 2007;48:1745)
  • T ALL constitutes 15% of childhood and 20 - 25% of adult ALL cases
  • T LBL constitutes 85 - 95% of LBL, usually presents as mediastinal mass with no / minimal marrow involvement
  • CNS involvement if untreated
  • T LBL frequently presents with mass in anterior mediastinum, rapid growth, respiratory emergency, pleural effusion
  • Younger (age 16 - 60 years) patients compared to older (61+ years) patients have more hepatosplenomegaly, present with mediastinal mass and lymphadenopathy; myeloid antigens and lineage inappropriate gene rearrangements are less common (Am J Clin Pathol 2002;117:252)
  • Diagnosis: T ALL if lymphoblasts are 25% or more of marrow cells; T LBL otherwise
Prognostic factors
  • Chemotherapy cures 60%
  • Patients have earlier relapse, induction failure and isolated CNS relapse compared to preB ALL
Microscopic (histologic) description
  • Similar to B cell disease; scant cytoplasm, delicate chromatin, indistinct nucleoli, convoluted nuclear membrane and grooves
  • Frequent mitotic figures; starry sky pattern produced by interspersed benign macrophages
  • Usually features of FAB L1 or L2; pattern in marrow is usually interstitial
  • Lymph nodes: complete architectural effacement or partial involvement with paracortical infiltrate with germinal center sparing
  • Thymus: replacement of normal parenchyma
  • Occasionally eosinophilia and myeloid hyperplasia with variable t(8;13)(p11.2;q11-22) involving FGFR1 gene; some develop myeloid malignancy (MDS, AML, or myeloid sarcoma)
Microscopic (histologic) images

Images hosted on PathOut server:
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Blood smear shows markedly elevated leukocyte count
with variable lymphoblast size and chromatin density

L2 type (blood smears):
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Large leukemic blasts; also small cells with minimal
cytoplasm, markedly hyperchromatic nuclei and prominent
nuclear convolution, suggestive of T cell ALL

Bone marrow biopsy:
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Sheets of lymphoblasts with variable size and
moderate nuclear irregularity, also mitotic figures

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Focal paranuclear acid phosphatase staining

Positive stains
Negative stains
  • CD19, CD20; double negative CD4 / CD8 (40%)
  • Note: ALL with aberrant myeloid antigen expression is correct name, not biphenotypic leukemia
Molecular / cytogenetics description

  • MYC (8q24.1)
  • TAL1 (1p32)
  • RBTN1 (LMO1) (11p15)
  • RBTN2 (LMO2) (11p13)
  • HOX11 (TLX1) (10q24)
  • HOX11L2 (TLX3) (5q35)
  • LYL1 (19p13)
  • LCK (1p34.3-35)
Molecular / cytogenetics images

Images hosted on other servers:
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Rearrangements involving T cell receptor genes

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FISH: t(5;14)(q35;q32)

Differential diagnosis
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