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Peripheral T-cell lymphoma, pleomorphic medium and large cell
Peripheral T-cell lymphoma, pleomorphic small cell
T-cell lymphoma, NOS
T-zone T-cell lymphoma
A large group of lymphomas which we collectively refer to as peripheral T-cell lymphomas with the optional addition of "unspecified" to emphasize that these cases do not belong to any better defined entities. Attempts to distinguish between them on morphological basis have met with poor reproducibility.
Peripheral T-cell lymphoma, NOS (PTCL) presents with peripheral lymph node involvement but any site may be affected. Disease is often generalized with infiltrates in the bone marrow, liver, spleen, and extranodal tissue. Peripheral blood is sometimes involved, but leukemic presentation is uncommon. Extranodal presentations may occur with the skin and GI tract representing the most commonly affected areas. Other less frequently involved sites include the lung, salivary gland, and CNS. The diagnosis of PTCL, NOS would be made ONLY when other specific entities have been excluded. Patients most often present with LN enlargement and a majority have advanced disease with B-symptoms. Paraneoplastic features such as eosinophilia, pruritis, or rarely hemophagocytic syndrome may be seen.
There are four variants of PTCL, NOS: Lymphoepitheliod (Lennert lymphoma); follicular T-cell lymphoma, NOS; T-zone lymphoma, and anaplastic large cell lymphoma, ALK-negative.
Lymphoepitheliod (Lennert lymphoma) shows diffuse or more rarely interfollicular growth. There can be scattered Reed-Sternberg-like cells (usually EBV+). In the majority of cases the neoplastic cells are CD8 positive.
Follicular T-cell lymphoma, NOS (perifollicular T-cell lymphoma, intrafollicular T-cell lymphoma, paracortical nodular T-cell lymphoma, expanded Mantle zone T-cell lymphoma) usually consists of atypical clear cells forming intrafollicular aggregates (mimicking follicular lymphoma), small nodular aggregates in a background of progressively-transformed germinal center (mimicking nodular lymphocyte-predominant Hodgkin lymphoma), or enlarged perifollicular zones/nodular aggregates surrounding hyperplastic follicles (mimicking nodal Marginal zone lymphoma). Partial lymph node involvement, lack of enlarged follicular dendritic cells and meshworks and lack of prominent high endothelial venules distinguish it from typical angioimmunoblastic T-cell lymphoma.
T-zone T-cell lymphoma variant is characterized by a perifollicular growth pattern throughout the lymph node. Some studies suggest this variant may have a more indolent course than other PTCL, NOS.
Anaplastic large cell lymphoma, ALK-negative (ALCL-ALK negative involves both lymph nodes and extranodal tissue although the latter sites are less commonly involved than in ALCL-ALK+.) Extranodal sites include bone, soft tissues, and skin.
These are highly aggressive lymphomas with a poor response to therapy. There are frequent relapses and the 5-year overall survival and failure-free survival is 20-30%.
Definitive Diagnostic Methods
Recurrent chromosomal genes 7q, 8q, 17q, and 22q
Recurrent losses in chromosomes 4q, 5q, 6q, 9p, 10q, 12q, and 13q
T-cell receptor (TCR) genes are clonally rearranged
CD3+ (T-zone variant)
CD4+ (NOS and T-zone variant)
CD8+ (lymphoepitheliod variant)
CD30+ (alcl, ALK negative)
Scattered Reed-Stermberg-like cells usually EBV+ (Lymphoepitheliod variant)