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WHO Classification of Tumours
Anaplastic large cell lymphoma, ALK negative
Tumours of haematopoietic and lymphoid tissues


Definition

ALK-negative anaplastic large cell lymphoma (ALCL, ALK-) is included as a provisional entity, and is defined as a CD30+ T-cell neoplasm that is not reproducibly distinguishable on morphological grounds from ALK-positive ALCL (ALCL, ALK+), but lacks anaplastic large cell lymphoma kinase (ALK) protein. Most cases express T-cell-associated markers and cytotoxic granule-associated proteins. ALCL, ALK- must be distinguished from primary cutaneous anaplastic large cell lymphoma , other subtypes of CD30+ T- or B-cell lymphoma with anaplastic features, and classical Hodgkin lymphoma (CHL).

> Synonyms and historical annotation

ALCL, ALK- was included in the third edition of the WHO classification, together with ALCL, ALK + in the broader entity of “anaplastic large cell lymphoma”

Click to access Pubmed
Delsol G, Ralfkiaer E, Stein H, Wright D, Jaffe ES (2001)
Anaplastic large cell lymphoma.
In: WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues, 3rd Edition. Pathology and Genetics. IARCPress: Lyon: pp 230–235.



. However, it was also recognized that ALCL, ALK- (mainly because of their older median age and more aggressive clinical course) are felt to be distinct from ALCL, ALK+
Click to access Pubmed
Delsol G, Ralfkiaer E, Stein H, Wright D, Jaffe ES (2001)
Anaplastic large cell lymphoma.
In: WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues, 3rd Edition. Pathology and Genetics. IARCPress: Lyon: pp 230–235.



. However, there are also valid arguments for excluding ALCL, ALK- from the category of peripheral T-cell lymphoma (PTCL), not otherwise specified (NOS)
Click to access Pubmed
Falini B (2001)
Anaplastic large cell lymphoma: pathological, molecular and clinical features.
Br J Haematol 114: 741-60




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Jaffe ES (2001)
Anaplastic large cell lymphoma: the shifting sands of diagnostic hematopathology.
Mod Pathol 14: 219-28




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Skinnider BF, Connors JM, Sutcliffe SB, Gascoyne RD (1999)
Anaplastic large cell lymphoma: a clinicopathologic analysis.
Hematol Oncol 17: 137-48




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Wolf BC, Kumar A, Vera JC, Neiman RS (1986)
Bone marrow morphology and immunology in systemic amyloidosis.
Am J Clin Pathol 86: 84-8



. Unfortunately, there are few detailed clinicopatho - logical studies of ALCL, ALK-
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ten Berge RL, Oudejans JJ, Ossenkoppele GJ, Meijer CJ (2003)
ALK-negative systemic anaplastic large cell lymphoma: differential diagnostic and prognostic aspects--a review.
J Pathol 200: 4-15



and no specific oncogenic abnormalities (e.g. comparable to ALK gene rearrangement) have been identified. Thus, the distinction between PTCL, NOS, and ALCL, ALK- is not always straightforward. The current WHO Classification considers ALCL, ALKto be a provisional entity within the spectrum of mature T-cell lymphomas, distinct from both ALCL, ALK+ and PTCL, NOS.

> Related Topics
Anaplastic large cell lymphoma, ALK positive
Primary cutaneous anaplastic large cell lymphoma
Peripheral T-cell lymphoma, (NOS)
Introduction: Classification of lymphoid neoplasms