![]() ![]() BIA-ALCL is included as a provisional entity in the 2017 WHO classification. 3 BIA-ALCL represents a distinct entity from systemic ALCL and other forms of primary breast lymphoma (which are usually of B-cell origin). 15 In the 2017 WHO classification, ALCL, ALK-negative is listed as a definite entity. 14 Most patients with systemic ALCL present with advanced stage III or IV disease (65% for ALK-positive and 58% for ALK-negative) frequently associated with systemic symptoms and extranodal involvement. ALCL, ALK-positive is most common in children and young adults and is characterized by the overexpression of ALK-1 protein, resulting from a chromosomal translocation in 40%–60% of patients. There are now 4 distinctly recognized subtypes of ALCL: systemic ALCL, ALK-positive systemic ALCL, ALK-negative breast implant-associated ALCL (BIA-ALCL), and primary cutaneous ALCL. 5, 13ĪLCL is a CD30-expressing subtype that accounts for fewer than 5% of all cases of NHL. 10 – 12 AITL occurs mainly in older patients, and the prognosis is similar to PTCL-NOS. 10 AITL is also characterized by the frequent presence of Epstein-Barr virus (EBV)-positive B cells and cases of coexistent EBV+DLBCL are reported. 3ĪITL is the classic form of the TFH phenotype, usually presents with generalized lymphadenopathy, and is often with associated hypergammaglobulinemia, hepatomegaly or splenomegaly, eosinophilia, skin rash, and fever. ![]() WHO classification also recognizes the clinical significance of GATA3 and TBX21 expression in PTCL-NOS subtypes. 6 – 9 In a multivariate analysis, a high international prognostic index (IPI) score and PTCL-GATA3 subtype identified by IHC were independently associated with poor OS. 4, 5 Gene expression profiling studies and immunohistochemistry (IHC) algorithms have identified 2 major molecular subgroups of PTCL-NOS (characterized by high expression of either GATA3 or TBX21). PTCL-NOS is associated with poorer overall survival (OS) and event-free survival (EFS) rates compared with aggressive B-cell lymphomas. PTCL-NOS most often involves nodal sites however, many patients present with extranodal involvement, including the liver, bone marrow, gastrointestinal tract, and skin. 2 In the 2017 WHO classification, nodal PTCL with T-follicular helper (TFH) phenotype (PTCL,TFH) and follicular T-cell lymphoma (FTCL) are also included as provisional entities of TFH origin (which were previously classified as PTCL-NOS). 1 PTCL-not otherwise specified (PTCL-NOS 26%) is the most common subtype, followed by angioimmunoblastic T-cell lymphoma (AITL 19%), anaplastic large cell lymphoma (ALCL), anaplastic lymphoma kinase (ALK)-positive (7%), ALCL, ALK-negative (6%), and enteropathy-associated T-cell lymphoma (EATL <5%). ![]() Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoproliferative disorders arising from mature T-cells, accounting for about 10% of non-Hodgkin lymphomas (NHLs). ![]()
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