The virus HTLV-1 is associated with adult T cell lymphoma/leukemia in Japan and the Carribean islands and is likely significant for the pathogenesis of this T cell lymphoma. Otherwise, there are no known environmental factors increasing the chance for developing these lymphomas. Enteropathy-type T cell lymphoma in adults is observed in patients with coeliac disease.
Overview of T/NK cell lymphomas
T cell pre-stages
- T-lymphoblastic leukemia/lymphoblastic lymphoma
Mature T/NK cell lymphomas
- Primary cutaneous anaplastic large cell lymphoma
- Mycosis fungoides/Sezary syndrome
- Aggressive T/NK cell lymphomas
- Enteropathy-type T cell lymphoma
- Hepatosplenic T cell lymphoma
- Angioimmunoblastic T cell lymphoma (AILT)
- Peripheral T cell lymphoma, UNS
- Anaplastic large cell T/0 cell lymphoma
The group is heterogenous and the morphology varies significantly between the different subgroups.
Monoclonal rearrangement of T cell receptor γ/δ may be helpful where it is difficult to determine a certain diagnosis of malignancy. Most T cell lymphomas are CD4+/CD8 except for subcutaneous panniculitis-like T celle lymphoma (CD4-/CD8+), enteropathy-type T cell lymphomas (CD4-/ CD8+) and hepatosplenic γ/δ T cell lymphoma (CD4–/CD8–).
In total, the group constitutes about 10% of NHL in which peripheral T cell lymphoma UNS is the largest subgroup (about 4%).
With the exception of primary cutaneous anaplastic large cell lymphoma, anaplastic large cell alk+ T cell lymphoma and mycosis fungoides, the prognosis for mature T cell lymphomas is poorer than for large cell B cell lymphomas. Five-year survival varies between 10% and 45%. The poorer prognosis is partly due to a larger number of patients with poor prognostic factors (high IPI score) and partly that T cell phenotype itself indicates a poorer prognosis. Certain subgroups have an especially poor prognosis (extranodal NK/T cell lymphoma, hepatosplenic T cell lymphoma, enteropathy-type T cell lymphomas).
Aggressive T/NK cell lymphomas
Intensive chemotherapy is considered very important for this group since the overall prognosis is worse than for aggressvie B cell lymphomas.
The treatment goal is curative.
CHOP-based chemotherapy is preferred. It is recommended that patients < 65 years in stage II-IV are given CHOEP14, 6 cycles, (CHOP14 for patients 60-65 years), followed by HDT with SCS. Preferably, patients in this category under 60 years should be included in a multicenter phase III study initiated by the Nordic Lymphoma Group where treatment is CHOP14 +/- alemtuzumab, followed by HDT with SCS. Patients > 65 years stages II-IV are treated with CHOP14 with elevated LDH, otherwise CHOP21.
For localized disease, the same principles are followed as for aggressive B cell lymphomas, that is, 3-6 cycles followed by radiotherapy to the involved field with 2 Gy x 20 fractionation.
Patients with aggressive T/NK cell lymphomas in stages II–IV (enteropathy-type T cell lymphoma, hepatosplenic T cell lymphoma, angioimmunoblastic T cell lymphoma, peripheral T cell lymphoma UNS, NK/T cell lymphoma of nasal type) < 60 years are preferably included in a multicenter phase III study initiated by the Nordic Lymphoma Group, where they are treated with CHOP14 +/- alemtuzumab, followed by HDT with SCS.