What is the difference between Peripheral T-cell Lymphoma (PTCL) and Angioimmunoblastic T-cell Lymphoma (AITL)?

From the Guidelines

Peripheral T-cell lymphoma (PTCL) and angioimmunoblastic T-cell lymphoma (AITL) are distinct subtypes of non-Hodgkin lymphomas with different characteristics, and AITL is a specific subtype within the PTCL group that typically presents with generalized lymphadenopathy, hepatosplenomegaly, skin rash, and systemic symptoms. The main differences between PTCL and AITL are:

• PTCL is a broader category that includes several subtypes of T-cell lymphomas, while AITL is a specific subtype within the PTCL group 1.
• AITL typically presents with generalized lymphadenopathy, hepatosplenomegaly, skin rash, and systemic symptoms like fever and weight loss, along with characteristic immunological abnormalities such as hypergammaglobulinemia and autoimmune phenomena 1.
• Genetically, AITL frequently shows mutations in TET2, RHOA, and IDH2, while PTCL-NOS has more heterogeneous genetic alterations 1.
• Both conditions are typically treated with anthracycline-based chemotherapy regimens like CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone), often followed by stem cell transplantation in eligible patients, though AITL may sometimes respond to immunomodulatory approaches due to its immune dysregulation component 1. Some key points to consider in the treatment of PTCL and AITL include:
• The prognosis of PTCLs is generally poorer than that of aggressive B-cell lymphomas, with a 3-year PFS and OS rate of 32% and 52%, respectively 1.
• ALCL, ALK-positive is associated with better clinical outcomes than ALCL, ALK-negative, PTCL-NOS, or AITL, with a 5-year FFS rate of 60% and OS rate of 70% 1.
• A novel prognostic score (AITL score) based on age, ECOG performance score, elevated C-reactive protein, and elevated β2 microglobulin can stratify patients into 3 risk groups with estimated 5-year OS rates of 63%, 54%, and 21%, respectively 1.

From the Research

Overview of PTCL and AITL

• Peripheral T-cell lymphoma (PTCL) is a category of non-Hodgkin lymphoma that originates from T-cells [(2,3,4)].
• Angioimmunoblastic T-cell lymphoma (AITL) is a subtype of PTCL, representing about 15-20% of cases 2.
• AITL is characterized by a unique clinical presentation and distinct pathologic and molecular features [(2,3)].

Clinical Presentation and Diagnosis

• AITL typically presents with advanced disease, systemic symptoms, and immune deregulation [(4,5)].
• Diagnosis of AITL is challenging and requires a constellation of clinical, laboratory, and histopathological findings 3.
• Significant progress has been made in understanding the molecular pathophysiology of AITL, with characteristic genomic features recognized 3.

Treatment Approaches

• Frontline treatment for AITL typically involves chemotherapy, with consideration for autologous stem-cell transplant (SCT) 4.
• In the relapsed and refractory settings, allogeneic SCT offers the chance for long-term remission 4.
• Novel agents, such as brentuximab vedotin, have shown promise in AITL treatment [(6,4)].
• Ongoing studies are evaluating new potential targets for AITL, with a focus on identifying markers of response and resistance 4.

Comparison of PTCL and AITL

• PTCL is a broader category of lymphoma, while AITL is a specific subtype [(2,3)].
• AITL has distinct clinical and pathological features compared to other types of PTCL [(2,3)].
• Treatment approaches for AITL may differ from those for other types of PTCL, with a focus on targeted therapies and SCT [(6,4)].