Abstract
We studied six cases of a novel type of nodal peripheral T-cell lymphoma. Three cases with this disease were recently described by de Leval et al. (de Leval L, Savilo E, Longtine J, et al. Peripheral T-cell lymphoma with follicular involvement and a CD4+/bcl-6+ phenotype. Am J Surg Pathol2001;25:395–400). The entity was named peripheral T-cell lymphoma with follicular involvement because of its distinctive histological features. We report an additional six well-characterized cases and describe the molecular and cytogenetic findings. The neoplastic T-cells of this lymphoma type express CD4 and Bcl-6, and home to the B-lymphoid follicles. This suggests an origin of the lymphoma from an as yet poorly characterized subset of Bcl-6 expressing intra-follicular T-helper cells. Of interest, the cytogenetic data and/or the study of T-cell receptor gamma gene rearrangements revealed more than one clone in each case. Cytogenetics further revealed complex karyotypes without recurrent chromosomal aberrations. We also studied the presence of somatic mutations in the 5′ untranslated region of the BCL-6 gene in four of the cases but no somatic hypermutation was detected. Clinically, the cases presented with widespread lymph node involvement at diagnosis and multiple relapses occurred after treatment. All patients received a CHOP-based chemotherapy regimen, later followed by high dose chemotherapy with stem cell rescue in five patients. One patient died with lymphoma and hemophagocytic syndrome 24 months after diagnosis, one patient is alive with disease after 27 months from diagnosis, whereas the other four patients are in complete remission 12 to 124 months after diagnosis. In conclusion, we confirm that peripheral T-cell lymphoma with follicular involvement is a distinct lymphoma type and we show that the lymphoma is oligo-clonal. The clinical findings are those of an intermediately aggressive lymphoma type. Although minimal lymph node infiltration with lymphoma cells at diagnosis and oligo-clonality is also characteristic of angio-immunoblastic T-cell lymphoma, we believe that peripheral T-cell lymphoma with follicular involvement is a distinct T-cell lymphoma type. In contrast to angio-immunoblastic T-cell lymphoma it is characterized by the typical infiltration of lymphoma cells in B-lymphoid follicles, coagulation necrosis, the absence of proliferation of high endothelial venules and follicular dendritic cells in T-cell areas, as well as the absence of EBV infection. It is likely that T-cell lymphoma with follicular involvement arises from Bcl-6+ intra-follicular T-cells. No recurrent genetic defects have been identified but the oligo-clonal nature of the lymphoma is intriguing. The latter suggests that the triggering oncogenic factors are external, such as infection.
An Unusual Case of Enteropathy-associated T-cell Lymphoma Type 2 with Pulmonary Metastasis