Peripheral T-cell lymphoma with involvement of the expanded mantle zone

Abstract

Peripheral T-cell lymphoma (PTCL) with a nodular architecture is rare. Recently, two variants have been described with infiltration of the B-cell follicle, one variant that localizes to the marginal zone with a so-called perifollicular growth pattern, and a variant that localizes to the germinal center. These lymphomas have a CD4+ phenotype and may express Bcl-6. We have studied five similar cases of PTCL with involvement of the B-cell follicle. However, our cases differ from the cases previously described by their predominant and frequently patchy involvement of the expanded mantle zone of the B-cell follicle at onset. Later biopsies in three of the cases show diffuse infiltration of the lymph node, without features of angioimmunoblastic TCL (AILT). All cases expressed Bcl-6 in addition to CD4. Cytogenetics was available in four of the cases but revealed no recurrent chromosomal aberrations or changes associated with other types of PTCL. No mutations of the BCL-6 gene were observed. Together, the cases seem to have an intermediately aggressive clinical behavior. Whether our cases are part of a spectrum of PTCLs that encompasses previously described variants with predominant marginal zone or germinal center infiltration or they represent a separate T-cell lymphoma type remains to be demonstrated by a study of more of such cases.

Nodal follicular helper T-cell lymphoma may present with different patterns. A case report

“…Our case shows that the same clone of T cell expressing a phenotype similar to that of normal follicular helper T cells may present with different patterns: AITL, a condition well known [1][2][3]6]; FTCL, a less frequent condition [7][8][9][10][11][13][14][15]; and PTCL-unspecified, large-cell predominant.…”

“…Different variants have been described, based on the predominant site of infiltration of the follicles by neoplastic helper T cells: a parafollicular or marginal zone type, a GC type, and a progressively transformed follicular type with mantle B-cell hyperplasia [7][8][9][10]. Combinations of patterns have been found in the same patient, either simultaneously or during progression: follicular T-cell lymphoma (FTCL) and AITL [10,11], FTCL and diffuse PTCL, unspecified [7], and FTCL transformed into a diffuse PTCL-unspecified [8]. The immunophenotype of the neoplastic helper T cells in these FTCLs is also that of the subtype of helper T cells observed in AITL.…”

The gene expression profile of nodal peripheral T-cell lymphoma demonstrates a molecular link between angioimmunoblastic T-cell lymphoma (AITL) and follicular helper T (TFH) cells

“…Our findings also reinforce the hypothesis of the relationship of AITL to a peculiar form of PTCL-u with a follicular growth pattern and suspected to be derived from germinal center T cells, 46 and perhaps to another form of PTCL with a parafollicular pattern of growth 47 or with involvement of the follicular mantle zone. 48 It is remarkable that a minor subset of normal T cells 34 would be the cell of origin of one of the most frequent type of T-cell lymphoma. In view of the major role of the B-cell follicle in B-cell lymphomagenesis, with more than half of mature B-cell lymphomas deriving from germinal center cells, it is questionable whether mechanisms of genetic alterations similar to those operating in B-cell transformation may also target T FH cells.…”

The inducible T-cell co-stimulator molecule is expressed on subsets of T cells and is a new marker of lymphomas of T follicular helper cell-derivation

“…In our study, the expression of ICOS was restricted to T-cell lymphomas, specifically to AITL and PTCL of follicular variant. This latter variant has only recently been described 43,44 and shows some morphological and many phenotypic features in common with AITL. 29,31 Overall, ICOS expression showed a close correlation with PD-1, but in contrast to PD-1, which was detected in some cases of B-cell lymphomas, 45 none of the investigated cases of B-cell neoplasms was ICOS-positive (Table 1) including three cases of diffuse large B-cell lymphoma that we previously reported to express PD-1.…”