The diagnosis of Sézary syndrome on peripheral blood by flow cytometry requires the use of multiple markers

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Flow cytometry for the assessment of blood tumour burden in cutaneous T-cell lymphoma: towards a standardised approach

Mycosis fungoides (MF) and Sézary syndrome (SS) are the best-studied subtypes of cutaneous T-cell lymphoma, a rare non-Hodgkin lymphoma that primarily presents in the skin but can also involve blood, lymph nodes, and viscera. The role of blood involvement in the assessment and staging of MF and SS has evolved in recent years from being classed as simply 'present' or 'absent', with no impact on staging, to full analysis of abnormal peripheral-blood T cells using flow cytometry (FC) to detect and quantify aberrant T-cell phenotypes and polymerase chain reaction (PCR) to characterise T-cell receptor gene rearrangements. These sensitive peripheral-blood assessments are replacing manual Sézary cell counts and have become an important part of clinical work-up in MF and SS, providing the potential for more accurate prognostication and appropriate management. However, although international recommendations now include guidelines for FC analysis of peripheral-blood markers for staging purposes, many clinics only perform these analyses in advanced-stage patients, if at all, and there is still a need for standardised use of validated markers. Standardisation of a single effective multiparameter FC panel would allow for accurate identification and quantification of blood tumour burden for diagnosis, staging, assessment of therapeutic response, and monitoring of disease progression at all stages of disease. Once defined, validation of an MF/SS biomarker FC panel will enable uptake into clinical settings along with associated standardisation of protocols and reagents. This review discusses the evolution of the role of FC in evaluating blood involvement in MF and SS, considers recently published international guidelines, and identifies evidence gaps for future research that will allow for standardisation of FC in MF and SS.

Cutaneous T-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Diagnosis and prognostic stratification of cutaneous lymphoma

Primary cutaneous lymphomas are a heterogenous group of non-Hodgkin's lymphoma of both T/natural killer-cell and B-cell origin and defined to primarily present in the skin without extracutaneous involvement at diagnosis. In contrast to nodal non-Hodgkin's lymphoma, cutaneous T-cell lymphomas (CTCL) are more generally seen than cutaneous B-cell lymphomas (CBCL). CTCL and CBCL have various subtypes and each subtype has specifically characteristic clinical, pathological, and prognostic features. The diagnostic methods and staging evaluation of cutaneous lymphomas is mostly common in various guidelines created by professional societies. The diagnosis is made comprehensively based on clinical, pathological, laboratory, radiological, and genetic findings. On the other hand, definite prognostic stratification has not been completely established yet in most cutaneous lymphomas. This article focuses on the general and novel diagnostic methods and the current findings about prognostic factors and stratification in cutaneous lymphomas.

Mycosis fungoides and Sézary syndrome: 2019 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, skin-directed therapies are preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies. These include biologic-response modifiers, histone deacetylase (HDAC) inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Cutaneous T-cell lymphoma: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Therapeutic Antibodies to KIR3DL2 and Other Target Antigens on Cutaneous T-Cell Lymphomas

KIR3DL2 is a member of the killer cell immunoglobulin-like receptor (KIR) family that was initially identified at the surface of natural killer (NK) cells. KIR3DL2, also known as CD158k, is expressed as a disulfide-linked homodimer. Each chain is composed of three immunoglobulin-like domains and a long cytoplasmic tail containing two immunoreceptor tyrosine-based inhibitory motifs. Beside its expression on NK cells, it is also found on rare circulating T lymphocytes, mainly CD8⁺. Although the KIR gene number varies between haplotype, KIR3DL2 is a framework gene present in all individuals. Together with the presence of genomic regulatory sequences unique to KIR3DL2, this suggests some particular functions for the derived protein in comparison with other KIR family members. Several ligands have been identified for KIR3DL2. As for other KIRs, binding to HLA class I molecules is essential for NK development by promoting phenomena such as licensing and driving NK cell maturation. For KIR3DL2, this includes binding to HLA-A3 and -A11 and to the free heavy chain form of HLA-B27. In addition, KIR3DL2 binds to CpG oligonucleotides (ODN) and ensures their transport to endosomal toll-like receptor 9 that promotes cell activation. These characteristics have implicated KIR3DL2 in several pathologies: ankylosing spondylitis and cutaneous T-cell lymphomas such as Sézary syndrome, CD30⁺ cutaneous lymphoma, and transformed mycosis fungoides. Consequently, a new generation of humanized monoclonal antibodies (mAbs) directed against KIR3DL2 has been helpful in the diagnosis, follow-up, and treatment of these diseases. In addition, preliminary clinical studies of a novel targeted immunotherapy for cutaneous T-cell lymphomas using the anti-KIR3DL2 mAb IPH4102 are now underway. In this review, we discuss the various aspects of KIR3DL2 on the functions of CD4⁺ T cells and how targeting this receptor helps to develop innovative therapeutic strategies.

The biomarker landscape in mycosis fungoides and Sézary syndrome

The practice of pre-emptive individualized medicine is predicated on the discovery, development and application of biomarkers in specific clinical settings. Mycosis fungoides and Sézary syndrome are the two most common type of cutaneous T-cell lymphoma, yet diagnosis, prognosis and disease monitoring remain a challenge. In this review, we discuss the current state of biomarker discovery in mycosis fungoides and Sézary syndrome, highlighting the most promising molecules in different compartments. Further, we emphasize the need for continued multicentre efforts to validate available and new biomarkers and to develop prospective combinatorial panels of already discovered molecules.

Epigenomic Analysis of Sézary Syndrome Defines Patterns of Aberrant DNA Methylation and Identifies Diagnostic Markers

Sézary syndrome (Sz) is a malignancy of skin-homing CD4(+) memory T cells that is clinically characterized by erythroderma, lymphadenopathy, and blood involvement. Distinction of Sz from erythroderma secondary to inflammatory skin diseases (erythrodermic inflammatory dermatosis [EID]) is often challenging. Recent studies identified recurrent mutations in epigenetic enzymes involved in DNA modification in Sz. Here we defined the DNA methylomes of purified CD4(+) T cells from patients with Sz, EID, and healthy control subjects. Sz showed extensive global DNA methylation alterations, with 7.8% of 473,921 interrogated autosomal CpG sites showing hypomethylation and 3.2% hypermethylation. Promoter CpG islands were markedly enriched for hypermethylation. The 126 genes with recurrent promoter hypermethylation in Sz included multiple candidate tumor suppressors that showed transcriptional repression, implicating aberrant methylation in the pathogenesis of Sz. Validation in an independent sample set showed promoter hypermethylation of CMTM2, C2orf40, G0S2, HSPB6, PROM1, and PAM in 94-100% of Sz samples but not in EID samples. Notably, promoter hypermethylation of a single gene, the chemokine-like factor CMTM2, was sufficient to accurately distinguish Sz from EID in all cases. This study shows that Sz is characterized by widespread yet distinct DNA methylation alterations, which can be used clinically as epigenetic diagnostic markers.

Cutaneous T-cell lymphoma (CTCL): Current practices in blood assessment and the utility of T-cell receptor (TCR)-Vβ chain restriction

BACKGROUND

Accurate quantification of malignant cells in the peripheral blood of patients with cutaneous T-cell lymphoma is important for early detection, prognosis, and monitoring disease burden.

OBJECTIVE

We sought to determine the spectrum of current clinical practices; critically evaluate elements of current International Society for Cutaneous Lymphomas (ISCL) B1 and B2 staging criteria; and assess the potential role of T-cell receptor-Vβ analysis by flow cytometry.

METHODS

We assessed current clinical practices by survey, and performed a retrospective analysis of 161 patients evaluated at Yale (2011-2014) to compare the sensitivity, specificity, positive predictive value, and negative predictive value of parameters for ISCL B2 staging.

RESULTS

There was heterogeneity in clinical practices among institutions. ISCL B1 criteria did not capture 5 Yale cohort cases with immunophenotypic abnormalities that later progressed. T-cell receptor-Vβ testing was more specific than polymerase chain reaction and aided diagnosis in detecting clonality, but was of limited benefit in quantification of tumor burden.

LIMITATIONS

Because of limited follow-up involving a single center, further investigation will be necessary to conclude whether our proposed diagnostic algorithm is of general clinical benefit.

CONCLUSION

We propose further study of modified B1 criteria: CD4/CD8 ratio 5 or greater, %CD4(+) CD26(-) 20% or greater, or %CD4(+) CD7(-) 20% or greater, with evidence of clonality. T-cell receptor-Vβ testing should be considered in future diagnostic and staging algorithms.

Cutaneous T-cell lymphoma: 2016 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Histopathological and immunophenotypical criteria for the diagnosis of Sézary syndrome in differentiation from other erythrodermic skin diseases: a European Organisation for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Task Force Study of 97 cases

BACKGROUND

Patients with erythrodermic disease are a diagnostic challenge regarding the clinical and histological differential diagnosis.

OBJECTIVES

To evaluate histopathological and immunohistochemical diagnostic markers for Sézary syndrome.

METHODS

Ninety-seven erythrodermic cases [Sézary syndrome (SS), n = 57; erythrodermic inflammatory dermatoses (EIDs), n = 40] were collected by the EORTC Cutaneous Lymphoma Task Force histopathology group. Evaluation criteria were (i) epidermal and dermal changes; (ii) morphology of the infiltrate; (iii) immunohistochemical analysis of marker loss (CD2, CD3, CD4, CD5 and CD7); (iv) bystander infiltrate by staining for CD8, FOXP3 and CD25; and (v) expression of Ki-67, CD30, PD-1 and MUM-1.

RESULTS

The workshop panel made a correct diagnosis of SS in 51% of cases (cutaneous T-cell lymphoma 81%) and of EID in 80% without clinical or laboratory data. Histology revealed a significantly increased degree of epidermotropism (P < 0.001) and more intraepidermal atypical lymphocytes (P = 0.0014) in SS biopsies compared with EID. Pautrier microabscesses were seen only in SS (23%) and not in EID (P = 0.0012). SS showed significantly more dermal cerebriform and blastic lymphocytes than EID. Immunohistochemistry revealed a significant loss of CD7 expression (< 50%) in 33 of 51 (65%) cases of SS compared with two of 35 (6%) EID (P < 0.001). The lymphocytic infiltrate in SS skin samples was found significantly to express PD-1 (P = 0.0053), MUM-1 (P = 0.0017) and Ki-67 (P < 0.001), and showed less infiltration of CD8(+) lymphocytes (P < 0.001). A multivariate analysis identified CD7 loss, increased numbers of small cerebriform lymphocytes, low numbers of CD8(+) lymphocytes and increased proliferation (Ki-67(+) lymphocytes) as the strongest indicators for the diagnosis of SS.

CONCLUSIONS

A number of different histological and immunophenotypical criteria are required to differentiate between SS and EIDs.

Promoter-Specific Hypomethylation Is Associated with Overexpression of PLS3, GATA6, and TWIST1 in the Sezary Syndrome

The Sézary Syndrome (SS) is an aggressive CD4+ leukemic variant of cutaneous T-cell lymphoma. Epigenetic modification of cancer cell genome is often linked to the expression of important cancer-related genes. Here we addressed the hypothesis that, in SS, DNA hypomethylation is involved in upregulation of PLS3, GATA6, and TWIST1, genes that are undetected in normal lymphocytes. Pyrosequencing analysis of CpG rich regions, and CpG dinucleotides within the 5' regulatory regions, confirmed hypomethylation of all three genes in SS, compared with controls. We then studied how methylation regulates PLS3 transcription in vitro using PLS3-negative (Jurkat) and PLS3-positive (HT-1080) cell lines. Treatment with the hypomethylating agent 5-azacytidine induced PLS3 expression in Jurkat cells and in vitro methylation of the cloned PLS3 promoter suppressed luciferase expression in HT-1080 cells. In conclusion, we show that promoter hypomethylation is associated with PLS3, GATA6, and TWIST1 overexpression in SS CD4+ T cells and that methylation can regulate PLS3 expression in vitro. The mechanisms of DNA hypomethylation in vivo and the functional role of PLS3, TWIST1, and GATA6 in SS are being investigated.

IPH4102, a humanized KIR3DL2 antibody with potent activity against cutaneous T-cell lymphoma

Advanced cutaneous T-cell lymphoma (CTCL) remains an unmet medical need, which lacks effective targeted therapies. In this study, we report the development of IPH4102, a humanized monoclonal antibody that targets the immune receptor KIR3DL2, which is widely expressed on CTCL cells but few normal immune cells. Potent antitumor properties of IPH4102 were documented in allogeneic human CTCL cells and a mouse model of KIR3DL2(+) disease. IPH4102 antitumor activity was mediated by antibody-dependent cell cytotoxicity and phagocytosis. IPH4102 improved survival and reduced tumor growth in mice inoculated with KIR3DL2(+) tumors. Ex vivo efficacy was further evaluated in primary Sézary patient cells, sorted natural killer-based autologous assays, and direct spiking into Sézary patient peripheral blood mononuclear cells. In these settings, IPH4102 selectively and efficiently killed primary Sézary cells, including at unfavorable effector-to-target ratios characteristic of unsorted PBMC. Together, our results offer preclinical proof of concept for the clinical development of IPH4102 to treat patients with advanced CTCL.

Blood flow cytometry in Sézary syndrome: new insights on prognostic relevance and immunophenotypic changes during follow-up

OBJECTIVES

Sézary syndrome (SS) is characterized by erythroderma, generalized lymphadenopathy, and the presence of circulating atypical lymphocytes, which are difficult to identify by morphologic data.

METHODS

We revised our series of 107 patients in an attempt to better define the phenotypic aberrancies in blood at diagnosis and the immunophenotypic stability over time detected by flow cytometry. Polymerase chain reaction assay was also used to study CD26/dipeptidyl peptidase IV (DPPIV) gene methylation.

RESULTS

The most common aberrancies were represented by the lack of CD26 (96/107) or CD38 (101/107) expression and the presence of a "dim" CD3, CD4, or CD2 population. There was a high variability in CD7 expression. In total, 31% of the patients had phenotypical heterogeneity in CD26 and CD7 expression at diagnosis. The phenotype was stable over time in 73 of 95 patients with available follow-up data, while 22 of 95 patients developed changes in CD26, CD7, or CD2 expression. CD4+CD26- SS showed hypermethylation of the CpG islands for the promoter region of CD26/DPPIV. Multivariate analysis showed that CD26 expression is a favorable prognostic factor (hazard ratio, 2.94; P = .045).

CONCLUSIONS

We confirm the relevance of CD26 negativity in SS diagnosis and monitoring. Nevertheless, the presence of rare CD26+ cases suggests that a multiparameter flow cytometry approach should be used. Changes in methylation profile could account for phenotypical heterogeneity.

Cutaneous lymphomas

Primary cutaneous lymphomas are extranodal non-Hodgkin lymphomas. They are classified into the two main groups of primary cutaneous T- and B-cell lymphomas. Very rare cases are derived from NK or plasmacytoid dendritic cells. The annual incidence is 1/100,000. Two-thirds of the patients have primary cutaneous T-cell lymphoma, and the remaining one-third have primary cutaneous B-cell lymphoma. Over the years, tremendous progress has been made regarding the diagnostics and classification of cutaneous lymphomas. An exact classification of cutaneous lymphomas is of great importance for the patient, because the different skin lymphomas have very different prognoses and require different therapeutic regimens. The basis for making a diagnosis is a clinical-pathological correlation, including the use of several immunohistochemical markers and molecular biological methods. Treatment of cutaneous lymphoma is adapted to the type of lymphoma and disease stage. First-line therapy consists of treatments that target the skin. Systemic treatment is used in advanced disease. Many targeted therapies have been introduced into routine clinical care in recent years. This review presents an up-to-date approach to the diagnosis and treatment of primary cutaneous lymphomas.

Cutaneous T-cell lymphoma: 2014 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, and blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. Multiagent chemotherapy (e.g., CHOP) may be employed for those patients with extensive visceral involvement requiring rapid disease control. In highly selected patients, allogeneic stem-cell transplantation may be considered.

KIR3DL2/CpG ODN interaction mediates Sézary syndrome malignant T cell apoptosis

We previously identified the NK cell receptor KIR3DL2 as a valuable diagnostic and prognostic marker for the detection of the tumoral T cell burden of Sézary syndrome (SS) patients. However, the function of this receptor on the malignant T lymphocyte population remained unexplored. We here demonstrate that engagement of KIR3DL2 by its recently identified ligand CpG oligodeoxynucleotide (ODN) induces the internalization of the receptor and leads to a caspase-dependent apoptosis of malignant T cells. This process of cellular death is correlated to a dephosphorylation of the transcription factor STAT3 (signal transducer and activator of transcription 3), which is found constitutively phosphorylated and activated in Sézary cells. Our results indicate that KIR3DL2 can directly promote SS malignant cell death through the use of CpG ODN.

Staphylococcal enterotoxins stimulate lymphoma-associated immune dysregulation

Patients with cutaneous T-cell lymphoma (CTCL) are frequently colonized with Staphylococcus aureus (SA). Eradication of SA is, importantly, associated with significant clinical improvement, suggesting that SA promotes the disease activity, but the underlying mechanisms remain poorly characterized. Here, we show that SA isolates from involved skin express staphylococcal enterotoxins (SEs) that induce crosstalk between malignant and benign T cells leading to Stat3-mediated interleukin-10 (IL-10) production by the malignant T cells. The SEs did not stimulate the malignant T cells directly. Instead, SEs triggered a cascade of events involving cell-cell and asymmetric cytokine interactions between malignant and benign T cells, which stimulated the malignant T cells to express high levels of IL-10. Much evidence supports that malignant activation of the Stat3/IL-10 axis plays a key role in driving the immune dysregulation and severe immunodeficiency that characteristically develops in CTCL patients. The present findings thereby establish a novel link between SEs and immune dysregulation in CTCL, strengthening the rationale for antibiotic treatment of colonized patients with severe or progressive disease.

Sézary Syndrome

Sézary syndrome (SS), a type of cutaneous T-cell lymphoma with a poor prognosis, is characterized by erythroderma and leukemic involvement. Because of the rarity of SS and difficulty in diagnosis, data on this aggressive malignancy are scarce. In this review, the diagnosis and pathology of SS are summarized and an update is provided, highlighting microscopic features and novel molecular findings. The diagnostic challenge of SS is described, with an emphasis on the differential diagnosis of erythroderma and key points in distinguishing SS from other cutaneous T-cell malignancies. Finally, the prognosis is discussed, focusing on large, recent studies of SS patients.

Aberrant expression of CD56 by circulating Sézary syndrome malignant T lymphocytes

Sézary syndrome (SS) is an aggressive variant of cutaneous T cell lymphoma characterized by the presence of malignant T cells in the skin, peripheral blood and lymph nodes. The tumoral population typically displays a CD3⁺ CD4⁺ CD45RO⁺ memory T cell phenotype. We report a case of SS with an aberrant CD56⁺ immunophenotype. This patient presented with a generalized erythroderma and palpable small axillary lymph nodes. SS (stage IVA) was diagnosed on histological criteria and by the detection of a major T cell clone in skin and blood, an elevated CD4/CD8 T cell ratio and Sézary cells count > 1000/mm³. Beside the Sézary cell marker KIR3DL2, immunostainings revealed that two third of the malignant cells expressed CD56 but no other natural killer (NK) cell marker such as CD16, CD160 or NKp46. This atypical expression was not linked to an activation-dependent process and remained stable during the time course of the disease. No loss of the pan T-cell markers CD2, CD3 or CD4 was detected while a complete down-modulation of CD26 was observed. Despite several lines of treatment, no durable amelioration was observed and patient died after 10 mo of follow-up. Because this CD4⁺ CD56⁺ SS case is the only one reported so far, the functional significance of CD56 expression remained difficult to assess in terms of aggressiveness and prognosis.

Peripheral blood sCD3⁻ CD4⁺ T cells: a useful diagnostic tool in angioimmunoblastic T cell lymphoma

Angioimmunoblastic T cell lymphoma (AITL) belongs to the subgroup of mature T cell lymphomas according to the World Health Organization and is one of the common T cell lymphomas in Western countries. Particularly in cases in which histological confirmation cannot be easily achieved, immunophenotyping of peripheral blood can give important information for the differential diagnosis of AITL. sCD3⁻ CD4⁺ T cells are a typical feature of AILT in flow cytometry of peripheral blood. In this retrospective study, the diagnostic value of flow cytometry for the diagnosis 'AITL' was assessed by comparing the frequency of sCD3⁻ CD4⁺ T cells in leukemic AITL patients and in patients with other leukemic CD4⁺ T cell lymphomas. Immunophenotyping of peripheral blood by flow cytometry was performed in a lymphocyte gate using fluorochrome-labelled antibodies against CD3, CD2, CD4, CD5, CD7, CD8, CD10, CD14, CD16, CD19, CD56, CD57 and T cell receptor. In 17/17 leukemic AITL patients, a small but distinct population of sCD3⁻ CD4⁺ T cells was detected (mean percentage of sCD3⁻ CD4⁺ T cells in the lymphocyte gate: 11.9 ± 15.4%, range 0.1-51.8%). In contrast, sCD3⁻ CD4⁺ T cells were found in only 1/40 patients with other leukemic CD4⁺ T cell lymphomas (one patient with mycosis fungoides). sCD3⁻ CD4⁺ T cells have a high positive predictive value (94%) for the diagnosis 'AITL'. Flow cytometry is particularly useful in the differential diagnosis of AITL, even if the aberrant T cell population has a very low frequency. Further biological characterization of this subfraction of lymphoma cells is warranted.

Natural killer reprogramming in cutaneous T-cell lymphomas: Facts and hypotheses

To better understand the pathogenesis of Sézary cells, distinguish them from reactive skin-infiltrating T-cells and improve disease treatment, efforts have been made to identify molecular targets deregulated by the malignant process. From immunophenotypic analysis and subtractive differential expression experiments to pan-genomic studies, many approaches have been used to identify markers of the disease. During the last decade several natural killer (NK) cell markers have been found aberrantly expressed at the surface of Sézary cells. In particular, KIR3DL2/CD158k, expressed by less than 2% of healthy individuals CD4⁺ T-cells, is an excellent marker to identify and follow the tumor burden in the blood of Sézary syndrome patients. It may also represent a valuable target for specific immunotherapy. Other products of the NK cluster on chromosome 19q13 have been detected on Sézary cells, raising the hypothesis of an NK reprogramming process associated with the malignant transformation that may induce survival functions.

Regulation of T-plastin expression by promoter hypomethylation in primary cutaneous T-cell lymphoma

T-plastin (PLS3) is an actin-bundling protein normally expressed in epithelial cells but absent in cells of hematopoietic origin. Aberrant PLS3 expression has been demonstrated in lymphocytes from Sézary syndrome (SS) patients and has been proposed as a biomarker for SS; however, the mechanism underlying dysregulation of PLS3 has not been determined. In this study, PLS3 mRNA expression was demonstrated in 21/35 (60%) SS patients and in 3/8 (38%) mycosis fungoides patients, all of whom had clonal blood involvement. No evidence for PLS3 mutations within coding or promoter regions was found, but significant hypomethylation of CpG dinucleotides 95-99 within the PLS3 CpG island was observed and this was restricted to the PLS3+ population. A polyclonal antibody specific to PLS3 was raised to examine coexpression of PLS3 with a panel of T-cell differentiation markers. All PLS3+ cells were CD3+CD4+ and CD26-, suggesting that loss of CD26 is consistently associated with gain of PLS3, whereas all other markers were distributed heterogeneously. However, a patient-specific TCR copy number assay also demonstrated heterogeneity in PLS3 expression in tumor cell populations. Importantly, our findings demonstrate PLS3 expression in the majority of SS patients and provide insight into the molecular regulation of PLS3 expression in CTCL.

Simplified flow cytometric assessment in mycosis fungoides and Sézary syndrome

By using flow cytometry with markers for CD3, CD4, CD26, and CD7, we examined the blood samples of 109 patients for abnormal T cells: 69 patients with mycosis fungoides (MF)/Sézary syndrome (SS), 31 hospitalized control subjects, and 9 patients with inflammatory skin disease. T cells were identified as quantitatively abnormal (>15% CD26- or CD7- T cells) or phenotypically abnormal (CD26- or CD7- T cells with bright or dim CD3 or CD4 or bright CD7). Patients were followed for a median of 82 months, and abnormal T cells were correlated with diagnosis, clinical outcome, and other laboratory parameters. Abnormal T-cell populations were identified in 46% of patients with MF/SS (32/69) and correlated with disease extent. Quantitative abnormalities were more frequent than phenotypic abnormalities, and CD4+/CD26- T cells were more frequent than CD4+/CD7- T cells. CD26- T cells correlated better with disease extent than did CD7 -. Increasing numbers of abnormal T cells were associated with worsening disease. Flow cytometry provides valuable information for diagnosis, prognosis, and therapeutic efficacy in MF/SS.

Cutaneous T-cell lymphoma: 2011 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

Tumor, node, metastasis, and blood (TNMB) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers, denileukin diftitox, and histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. Multiagent chemotherapy may be used for those patients with extensive visceral involvement requiring rapid disease control. In highly-selected patients with disease refractory to standard treatments, allogeneic stem-cell transplantation may be considered.

Peripheral blood findings in erythrodermic patients: importance for the differential diagnosis of Sézary syndrome

Although Sézary syndrome (SS) represents an advanced stage of cutaneous T-cell lymphoma, this diagnosis presents a challenge even for the most experienced dermatologic clinicians. SS is characterized clinically by erythroderma, but can also be identified in the presence of specific histologic and peripheral blood findings. Erythrodermic cutaneous T-cell lymphoma can mimic a number of nonmalignant disorders with erythroderma, including pityriasis rubra pilaris, psoriasis, atopic dermatitis, and graft-versus-host disease. The diagnosis is made even more challenging because the histology of SS is often nonspecific and rarely pathognomonic. As a result, peripheral blood studies in patients with erythroderma are frequently informative in the diagnosis of SS. Peripheral blood abnormalities including elevated CD4/CD8 ratio, aberrant CD26, CD27 and CD7 expression, and T-cell clonality can all be used to help arrive at a diagnosis. This review evaluates current data on the usefulness and limitations of specific peripheral blood markers detected by flow cytometry and T-cell receptor gene rearrangement polymerase chain reaction.

Characterization of the DNA copy-number genome in the blood of cutaneous T-cell lymphoma patients

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous non-Hodgkin's lymphoma that may variably involve the skin, lymph nodes, and peripheral blood. Malignant burden ranges from cutaneous patches and plaques with little evidence of blood involvement to erythroderma often in association with frank leukemia, as in Sézary syndrome. Toward a better understanding of the pathogenesis of this CD4+ T-cell malignancy, we conducted a high-resolution genomic analysis combining DNA (23 samples) and mRNA (12 samples) data of peripheral blood isolates from CTCL patients across a spectrum of stages. Strikingly, even patients with limited involvement, e.g., normal CD4 counts, contained significant copy-number alterations. Defining genomic characteristics of CTCL blood involvement included gains on 8q and 17q, and deletions on 17p and chromosome 10. A consensus analysis of 108 leukemic CTCL samples demonstrated global similarities among patients with varied blood involvement, narrowing 38 of 62 loci. Toward an annotated framework for in vitro testing, we also characterized genomic alterations in five CTCL cell lines (HH, HUT78, PNO, SeAx, and Sez4), revealing intact core features of leukemic CTCL. Together, these studies produce the most comprehensive view of the leukemic CTCL genome to date, with implications for pathogenesis, molecular classification, and potential future therapeutic developments.

Expression and function of the natural cytotoxicity receptor NKp46 on circulating malignant CD4+ T lymphocytes of Sézary syndrome patients

The natural cytotoxicity receptors NKp30, NKp44, and NKp46 were identified as activating receptors mainly expressed by natural killer (NK) lymphocytes. In this study we show that peripheral blood malignant CD4(+) T lymphocytes from patients with Sézary syndrome, an aggressive form of cutaneous T-cell lymphoma, express NKp46 at their cell surface. Although NKp46 does not behave as an independent functional receptor, its engagement provides a strong inhibiting signal on the malignant T lymphocyte CD3-induced proliferation. We show that this inhibition is correlated with a decreased phosphorylation of the CD3ζ chain associated with NKp46 and/or the TCR/CD3 complexes. Our results reveal that in addition to KIR3DL2/CD158k expression, NKp46 could represent an additional marker on the circulating malignant T lymphocytes of Sézary patients, where it displays an as yet unreported function of inhibitory co-receptor able to interfere with the processes governing their CD3-dependent proliferation.

A practical approach to the flow cytometric detection and diagnosis of T-cell lymphoproliferative disorders

The flow cytometric analysis of T-cell malignancies is difficult due to the heterogeneity of T-cells and the lack of convenient methods to detect T-cell clonality. Neoplastic T-cells are most often detected by their altered level of surface antigen expression, and detection requires an extensive knowledge of the phenotype of normal T-lymphocytes. This review focuses on the methods to distinguish malignant T-cells from their normal counterparts and the phenotypic features of the T-cell lymphoproliferative disorders.

The role of 9-O-acetylated ganglioside D3 (CD60) and {alpha}4{beta}1 (CD49d) expression in predicting the survival of patients with Sezary syndrome

BACKGROUND

Sézary syndrome is a rare and very aggressive leukemic variant of cutaneous T-cell lymphoma characterized by extensive skin involvement and a malignant circulating CD4(+) T-cell clone which homes to the skin, over-expresses CD60, and lacks CD7, CD26 and CD49d. So far prognostic markers in this disease are limited to treatment with systemic steroids, age, serum lactate dehydrogenase, and a white blood cell count of 20×10(9)/L or higher: no other biological marker with prognostic value, especially related to malignant cells, has been described.

DESIGN AND METHODS

We used flow activated cell sorting analysis to compare the distribution of the T-cell receptor-Vβ repertoire and several surface molecules (CD7, CD26, CD49d and CD60) within the circulating CD4(+) T-cell population in 62 patients with Sézary syndrome, 180 with mycosis fungoides, 6 with B-cell lymphomas, and 19 with chronic eczema. We calculated the 5-year overall survival of patients with Sézary syndrome after first hospital admission using Kaplan-Meier product-limit estimates and hazard ratios from the Cox proportional hazards model.

RESULTS

We found that both higher number of CD60(+) and lower number of CD49d(+) cells within circulating CD4(+) T cells at disease presentation were significantly associated with a lower probability of survival. An exceedingly high risk of death was observed for patients with a combination of a high proportion of CD4(+)CD60(+) cells (≥ 0.5×10(9)/L) and low proportion of CD4(+)CD49d(+) cells (<0.5×10(9)/L) (hazard ratio = 12.303, 95% confidence interval 1.5-95.9; P<0.02). In addition, a skewed usage of T-cell receptor-Vβ subfamilies was observed in the circulating T-cell clone for 61.9% of all patients with Sézary syndrome, T-cell receptor-Vβ 2 and 5.1 subfamilies being the most frequently represented (42.8%), followed by T-cell receptor-Vβ 12 and 13.1.

CONCLUSIONS

In this study we showed that up-regulation of CD60 and down-regulation of CD49d on circulating CD4(+) T cells are two useful markers for predicting a very poor outcome in patients with Sézary syndrome.

Combination therapy with extracorporeal photopheresis, interferon-alpha, PUVA and topical corticosteroids in the management of Sézary syndrome

BACKGROUND

Extracorporeal photopheresis (ECP) is recommended for the treatment of Sézary syndrome (SS), the leukemic variant of cutaneous T-cell lymphoma (CTCL). Several combination therapies are used to increase response rates to ECP.

PATIENTS AND METHODS

We report our experience with the combination therapy of ECP, interferon-alpha, PUVA and topical corticosteroids in SS.

RESULTS

The treatment outcome in 12 SS patients was retrospectively analyzed and showed an overall response rate to this combination treatment of 42 % with 4/12 patients achieving a partial remission and 1/12 patients a stable disease. The median overall survival time was 42 months. We investigated several clinical and laboratory parameters as an indicator for a response to treatment in our patient cohort. A combined analysis of the erythroderma assessment scale, WBC, LDH, CD4/CD8 ratio and the number of Sézary cells revealed that a reduction of several parameters significantly correlated with response to treatment. The parameters which correlated best with response were number of Sézary cells, CD4/CD8 ratio and WBC.

CONCLUSIONS

The investigated combination therapy was effective and well-tolerated in a subgroup of SS patients but needs to be evaluated in a larger patient population.

Flow cytometric detection of peripheral blood involvement by mycosis fungoides and Sézary syndrome using T-cell receptor Vbeta chain antibodies and its application in blood staging

Peripheral blood involvement has been recognized as an adverse prognostic factor in patients with mycosis fungoides and Sézary syndrome. However, accurate identification and enumeration of the neoplastic cells in these diseases can be challenging. We assessed the clinical utility of flow cytometric immunophenotypic analysis of T-cell receptor Vbeta expression in 82 mycosis fungoides and 6 Sézary syndrome patients, with an atypical T-cell immunophenotype, or abnormal CD4:CD8 ratio, identified from peripheral blood specimens of 723 patients submitted for routine mycosis fungoides/Sézary syndrome blood staging. To improve detection sensitivity, Vbeta expression was analyzed on gated CD3+CD4+ T cells or T cells with an aberrant immunophenotype, if present. The flow cytometric results were compared with traditional morphologic assessment (n=88) and molecular methods to assess the T-cell receptor gamma or beta genes (n=41 tested in parallel). Flow cytometric immunophenotyping yielded a clonal Vbeta pattern in 60/82 mycosis fungoides and 6/6 Sézary syndrome patients. By contrast, flow cytometric Vbeta was negative in all 10 healthy donors and 18 control patients, showing a specificity of 100% and concordance with molecular testing of 86%. Using flow cytometric Vbeta results instead of morphologic assessment, 12 patients were upstaged from B1 to B2, and 20 patients from B0 to B1 (P<0.0001). The 12 upstaged B2 patients had no morphologic evidence of involvement, but had an aggressive clinical course similar to those staged by traditional morphologic assessment (median survival 27 vs 41 months, log-rank P=0.701). In 30/44 patients with a tumor-associated Vbeta expression, a single Vbeta tube was used to monitor treatment response. In conclusion, flow cytometric Vbeta analysis is rapid and convenient, can assess T-cell clonality and tumor quantity simultaneously, and is useful both in initial blood staging and monitoring tumor burden during therapy in patients with mycosis fungoides or Sézary syndrome.

FOXP3+CD25- tumor cells with regulatory function in Sézary syndrome

Cutaneous T-cell lymphoma (CTCL) has been suggested by in vitro experiments to represent a malignant CD4+ T-cell proliferation with a regulatory T-cell (Treg) phenotype (CD4+CD25+FOXP3+). We investigated percentages of FOXP3+ and CD25+ cells in the blood of 15 Sézary, 14 mycosis fungoides (MF), and 10 psoriasis (Pso) patients and 20 normal healthy donors (NHDs). We found similar numbers of FOXP3+ cells in MF (10.4% of blood CD4+ cells) and Pso (11.1%) patients and NHDs (9.8%). In 8 of 15 (53%) Sézary patients, significantly reduced percentages of FOXP3+ cells were seen in blood (2.9%) and skin (10.4%). Interestingly, 6 of 15 (40%) Sézary patients showed significantly increased percentages of FOXP3+ cells (39.7% (blood), 20.3% (skin)); however, these cells did not express CD25. In these latter patients, clone-specific TCR-Vbeta-chain antibodies were used to demonstrate that these FOXP3+CD25- cells were monoclonal CTCL tumor cells. FOXP3+CD25- CTCL tumor cells showed a highly demethylated status of the foxp3 gene locus similar to Treg cells, and they were functionally able to suppress IL-2 mRNA induction in TCR-stimulated conventional T cells. Thus, FOXP3+CD25- CTCL tumor cells with functional features of Treg cells define a subgroup of Sézary patients who might carry a different prognosis and might require differential treatment.