Genetic changes in atypical hyperplasia and lymphoma with angioimmunoblastic lymphadenopathy and dysproteinaemia in the same patients

Peripheral T cell lymphoma, not otherwise specified: the stuff of genes, dreams and therapies

Peripheral T cell lymphomas (PTCL) account for about 12% of lymphoid tumours worldwide. Almost half show such morphological and molecular variability as to hamper any further classification, and to justify their inclusion in a waste-basket category termed “not otherwise specified (NOS)”. The latter term is used for neoplasms with aggressive presentation, poor response to therapy and dismal prognosis. In contrast to B cell lymphomas, PTCL have been the subject of only a limited number of studies to elucidate their pathobiology and identify novel pharmacological approaches. Herewith, the authors revise the most recent contributions on the subject based on the experience they have gained in the extensive application of microarray technologies. PTCL/NOS are characterised by erratic expression of T cell associated antigens, including CD4 and CD52, which have recently been proposed as targets for ad hoc immunotherapies. PTCL/NOS also show variable Ki-67 marking, with rates >80% heralding a worse prognosis. Gene expression profiling studies have revealed that PTCL/NOS derive from activated T lymphocytes, more often of the CD4+ type, and bear a signature composed of 155 genes and related products that play a pivotal role in cell signalling transduction, proliferation, apoptosis and matrix remodelling. This observation seems to pave the way for the use of innovative drugs such as tyrosine kinase and histone deacetylase inhibitors whose efficacy has been proven in PTCL primary cell cultures. Gene expression profiling also allows better distinction of PTCL/NOS from angioimmunoblastic T cell lymphoma, the latter being characterised by follicular T helper lymphocyte derivation and CXCL13, PD1 and vascular endothelial growth factor expression.

'Normal counterparts' of nodal peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCL) have been difficult to classify. A homogeneous principle of classification is still lacking, partly because lymph node compartments containing functionally distinct T-cell subsets have not been identified. A correlation to differentiated T-cell subsets, as CD4(+) or CD8(+) cells as well as cytotoxic populations has not revealed clinically meaningful entities. Upon antigen encounter, mature T-cells pass through distinct stages characterized by their surface molecule expression. Naïve T-cells are CD45RA(+)/CD45R0(-)/CD27(+)/CCR7(+), however, after antigen contact CD45RA expression is replaced by CD45R0. They differentiate to central memory cells, which retain CD27 and CCR7, or to effector-memory cells, which loose expression of both molecules depending on the strength of the antigen interaction. Immunohistological analysis of PTCL showed an effector or effector-memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(-)) for both angioimmunoblastic T-cell lymphoma (AILT) and anaplastic large cell lymphoma (ALCL), but different cytotoxic and activation markers expressed by these tumours. A subset of CD4(+) PTCL-not otherwise specified (PTCL-NOS) may correspond to a central memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(+)). Thus, a correlation of PTCL to stages of differentiation, rather than to the direction of differentiation, may reveal homogeneous categories. A comparison between the lymphomas and their normal counterparts may contribute to the understanding of the underlying transformation mechanisms.

Marker expression in peripheral T-cell lymphoma: a proposed clinical-pathologic prognostic score

PURPOSE

Although peripheral T-cell lymphoma, unspecified (PTCL/U), is the most common T-cell tumor in Western countries, no study to date has been based on the application of a wide panel of markers to a large series of patients and assessed the impact of phenotype on survival. We evaluated the expression of 19 markers in 148 PTCLs/U and 45 PTCLs of the angioimmunoblastic type (AILD).

PATIENTS AND METHODS

The analysis was performed on tissue microarrays by immunohistochemistry and in situ hybridization. Clinical data were available in 93 PTCL/U patients, most of whom had been included in a previous study proposing a prognostic index (PIT).

RESULTS

An aberrant phenotype with frequent loss of CD5 and/or CD7 was typical for PTCLs, irrespective of whether they were U or AILD. Aberrantly expressed proteins rarely included CD20, CD15, and CD30. Positivity for Epstein-Barr virus-associated small RNAs and CD15 expression emerged as adverse prognostic factors. Among PTCLs/U, the proliferation-associated protein Ki-67 turned out to be prognostically relevant and was integrated in a new predictive score, incorporating age (> 60 years), high lactate dehydrogenase, poor performance status, and Ki-67 > or = 80%. This score was associated with the patient outcome (P < .0001) and was found to be more robust than PIT (P = .0043) in the present series.

CONCLUSION

Our retrospective analysis shows a wide range of protein expression in PTCLs and proposes a new prognostic index. The latter represents one of the first examples of mixed score (including patient- and tumor-specific factors) applied to malignant lymphomas and may be the basis for future prospective therapeutic trials.

Identification of the tumor cells in peripheral T-cell lymphomas by combined polymerase chain reaction-based T-cell receptor beta spectrotyping and immunohistological detection with T-cell receptor beta chain variable region segment-specific antibodies

Most nodal peripheral T-cell lymphomas (PTCL) originate from alphabeta-T cells, and they often contain reactive T cells that may hamper immunophenotyping. To specifically identify the neoplastic population in immunohistochemically stained slides, we assessed the heterogeneity of the T-cell receptor beta chain variable region (TCRVbeta). This region contains 65 gene segments, of which only one is expressed after rearrangement. To investigate PTCL, we developed a polymerase chain reaction assay to define the clonally rearranged TCRVbeta segment. Detecting the corresponding epitope with segment-specific antibodies enabled identification of tumor cells among the T cells. The TCRVbeta segment of the tumor cells was defined in 13 of 13 PTCL not otherwise specified and 11 of 13 angioimmunoblastic T-cell lymphomas. Antibodies corresponding to the respective TCRVbeta segment of the tumor were available for seven cases from each group. After applying these antibodies in combination with antibodies against CD3, CD5, CD4, CD8, and cytotoxic molecules, double stains were evaluated by confocal laser scanning microscopy. In 9 of 14 cases, less than 50% of T cells expressed the clonally rearranged TCRVbeta segment. Phenotypes defined in double stains differed from those obtained by conventional immunohistochemistry in 11 of 14 cases. The combination of TCRVbeta polymerase chain reaction and immunohistochemistry may facilitate more reliable detection and characterization of tumor cells in PTCL.

Angioimmunoblastic T cell lymphoma is derived from mature T-helper cells with varying expression and loss of detectable CD4

Angioimmunoblastic T cell lymphoma (AILT) is a rare lymphoma that is regarded as a clinicopathologic entity but shows considerable histomorphologic diversity, variable immunophenotypes and inconsistent T cell receptor (TCR) gene rearrangement. One hundred four paraffin blocks of AILT were investigated defining tumor cell lineage by triple immunostains with a confocal laser scanning microscope and correlating morphology, immunophenotype and TCRgamma gene rearrangement to clinical outcome. Ninety-nine cases were CD4(+), some of them showing a mixture of CD4(+) and CD4(-) tumor cells. The remaining 5 specimens were CD3(+)/CD4(-)/CD8(-). A considerable number of T cells of different subtypes could always be found, but even in 13 cases predominated by CD8(+) cells, proliferation could be attributed to atypical CD4(+) cells. TCRgamma gene rearrangement was monoclonal in 48 cases (69%) among 70 tested. In 29 of these semi-quantitative gene scan analysis resulted in a median proportion of monoclonal peak of 35% of PCR-products. Clinical outcome was identical grouping patients by clonality of TCRgamma, absence or presence of clear cell clusters and international prognostic index. We conclude that AILT is mainly derived from CD2(+)CD3(+)CD4(+)CD5(+)CD7(-) mature T-helper cells with varying expression and partial loss of detectable CD4. A significant number of non-neoplastic T cells (resting CD4(+) T cells and activated small or medium-sized CD8(+) lymphocytes) may coexist with a minor neoplastic T cell population. Clinicopathologic correlation suggests AILT to be a well defined homogeneous entity with poor prognosis. Currently no prognostic factors can be derived.

Neoplastic T cells in angioimmunoblastic T-cell lymphoma express CD10

Angioimmunoblastic T-cell lymphoma (AITL) is a systemic disease involving lymph nodes, spleen, and bone marrow. Although the histologic features have been well described, the diagnosis is often challenging, as there are no specific phenotypic or molecular markers available. This study shows that the neoplastic cells of AITL can be identified by aberrant CD10 expression. Archival material from 30 cases of AITL, 10 cases of peripheral T-cell lymphoma unspecified (PTL), and 10 cases of reactive lymphoid hyperplasia were reviewed. Single and double immunostaining for CD3, CD4, CD8, CD20, CD21, CD10, BCL6, Ki67, and LMP-1 in situ hybridization for Epstein-Barr early region and polymerase chain reaction (PCR) for T-cell receptor gamma chain gene and immunoglobulin heavy chain gene were performed. Three overlapping histologic patterns with hyperplastic follicles, depleted follicles, or without follicles were identified in AITL. Of the 30 cases of AITL, 27 contained CD10(+) T cells. No CD10(+) T cells were present in the cases of PTL or reactive hyperplasia. PCR confirmed a monoclonal or oligoclonal T-cell population in 29 of 30 cases of AITL and a monoclonal B-cell population in 6 cases. Analysis of microdissected CD10(+) single cells showed that they belonged to the neoplastic clone. In conclusion CD10 is a phenotypic marker that specifically identifies the tumor cells in 90% of AITL, including the early cases. The presence of these cells distinguishes AITL from other PTLs. This finding provides an objective criterion for accurate and early diagnosis of AITL.

Angiogenesis and mast cells in non-Hodgkin's lymphoma: a strong correlation in angioimmunoblastic T-cell lymphoma

Mast cells are likely to play a role in angiogenesis under pathological conditions. Solid tumor growth is dependent on angiogenesis, but the influence of mast cells on angiogenesis in non-Hodgkin's lymphoma, (NHL) is not clear. We investigated mast cell number and vessel count in 61 cases of NHL. We also evaluated expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), both important cytokines for angiogenesis. The number of mast cells was greater in T-cell lymphomas than in B-cell lymphomas. Of the T-cell lymphomas, the greatest number of mast cells was observed in the angioimmunoblastic T-cell lymphoma (AIL). In all NHLs, significant correlation was found between vessel count and the number of mast cells (p < 0.0001) and between vessel count and the number of VEGF-expressing cells (p < 0.05) but not between vessel count and bFGF-expressing cells. Strong correlation was detected between the number of mast cells and the number of VEGF-expressing cells (p < 0.0001) in all NHLs. Double fluorescence staining of VEGF mRNA and mast cell tryptase revealed that mast cells expressed VEGF mRNA. Our data suggest that mast cells play a very important role in angiogenesis by expressing VEGF in NHL, especially in AIL.

Circulating CD4+ T lymphocytes with intracellular but no surface CD3 antigen in five of seven patients consecutively diagnosed with angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) accounts for less than 1% of all lymphatic malignancies. Oligoclonality or monoclonality for any of the T-cell receptor (TCR) chain genes can be demonstrated in the majority of the cases. During systematic screening for the presence of circulating lymphocytes with atypical coexpression of differentiation antigens in patients with T-cell lymphomas, we have discovered a minor population (accounting for 0.2% to 10.% of all lymphocytes) of atypical lymphocytes in the blood of five of seven patients consecutively diagnosed in 1997/1998 by lymph node histology to have AITL. The major distinguishing feature of these cells consists of the lack of the surface expression of the CD3 antigen, but not of the intracellular expression. These cells express the T-cell antigens CD2 and CD5 on their surface, but not CD7, and they express CD4 and CD45 at numbers of molecules per cell typical for T lymphocytes. Gene scan analyses for the TCR gamma chain revealed oligoclonality of these flow-sorted cells in one patient and monoclonality in two patients, the same patterns of TCR gamma chain gene as determined processing the respective diagnostic lymph nodes. Circulating CD4-expressing T lymphocytes with exclusively cytoplasmic expression of CD3 appear to represent the malignant population in patients with histologically diagnosed AITL.

An autopsy case of angioimmunoblastic T-cell lymphoma with a high content of epithelioid cells in the lymph node: immunohistochemical and genomic analyses

A 79-year-old female developed red papulonodular eruptions on her extremities, facial erythema, generalized lymphadenopathy and high fever. Histopathology of an affected lymph node showed the features of angioimmunoblastic T-cell lymphoma with a high content of epithelioid cells. She died about two years after the onset despite therapy. Genomic Southern blotting and immunostaining of the lymph nodes were performed twice. In August of 1993, Southern blotting did not show any rearrangement of the immunoglobulin or the T-cell receptor (TCR) gene. Small or medium-sized lymphoid cells were positive for CD4 or CD8 (CD4:CD8 = 2:1). However, in September of 1994 (at autopsy), rearrangements of TCK C beta 1, J beta 2 and J gamma genes were observed. Small or medium-sized lymphoid cells were positive for CD4, but negative for CD8. Several large cells were positive for Latent Membrane Protein 1 (LMP1) of the Epstein-Barr virus (EBV). Our results proved that selective oligoclonal proliferation of tumor cells (probably CD4+) accompanied the disease progress.

Clonal identification of trisomies 3, 5 and X in angioimmunoblastic lymphadenopathy with dysproteinemia by fluorescence in situ hybridization

Trisomies 3, 5 and X in six Japanese patients with AILD were detected by fluorescence in situ hybridization (FISH). Trisomies 3 and X were detected using centromeric probes. Cosmid probes locating on 5q31.1, the commonly deleted region, was used to detect trisomy 5. FISH detected three patients with trisomy 3 alone, one with trisomy 5 alone and one with all the three trisomies analysed. The sample that showed all three aberrations was further analysed by dual color FISH. The three trisomies were present on different cells. The AILD cells with trisomy 5 tended to replicate slowly, whereas those with trisomy 3 seem to have a proliferative advantage. An increase in the histopathological stage was reflected in the increase in the percentage of trisomy 3 cells in one patient.

Cutaneous involvement in prelymphomatous angioimmunoblastic lymphadenopathy

We describe prelymphomatous angioimmunoblastic lymphadenopathy with cutaneous involvement in a 73-year-old female patient. A maculopapular skin eruption was the first sign of the disease. Skin histology showed extensive perivascular and periadnexal mixed lymphoid infiltrates including centroblasts and immunoblasts with a high proliferative index and with focal erythrocyte extravasation. Lymph node histology confirmed the diagnosis, showing nearly complete effacement of the follicular architecture, a mixed lymphoid infiltrate, and numberous high endothelial venules in an expanded T-cell zone. Immunohistochemistry, however, demonstrated preservation of at least some follicular structures. T-cell receptor gene rearrangement analysis revealed oligoclonal patterns in both lymph node and skin specimens. In contrast, immunoglobulin heavy-chain gene rearrangement analysis revealed a polyclonal pattern. Accordingly, the disease was classified as a prelymphomatous stage of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) with specific involvement of both lymph node and skin. The patient was treated with high-dose corticosteroids, and long-lasting remission was induced. In contrast to our case, most reported cases of AILD show a monoclonal T-cell pattern indicating AILD-type lymphoma. Therefore we discuss the concept of prelymphomatous AILD developing into AILD-type lymphoma. Persistence of some antigenic stimulus may induce the proliferation of a monoclonal population of lymphoid cells from a polyclonal background in a multistep fashion. Proper treatment of AILD at an early, prelymphomatous stage may protract or inhibit development of full-blown, fatal AILD-type lymphoma.