Updated cutaneous T-cell lymphoma TNMB staging criteria fail to identify patients with Sézary syndrome with low blood burden.

Comparison of the 2007 EORTC/ISCL and the 2022 EORTC/ISCL/USCLC blood staging guidelines for cutaneous T-cell lymphoma at a single institution reveals the newer guidelines fail to detect a subset of patients with Sézary syndrome with low blood burden.

Phase II study of E7777 in Japanese patients with relapsed/refractory peripheral and cutaneous T-cell lymphoma.

E7777 is a recombinant cytotoxic fusion protein composed of the diphtheria toxin fragments A and B and human interleukin-2. It shares an amino acid sequence with denileukin diftitox, but has improved purity and an increased percentage of active monomer. We undertook a multicenter, single-arm phase II study of E7777 in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) to evaluate its efficacy, safety, pharmacokinetics, and immunogenicity. A total of 37 patients were enrolled, of which 17 and 19 patients had PTCL and CTCL, respectively, and one patient with another type of lymphoma (extranodal natural killer/T-cell lymphoma, nasal type), diagnosed by the Central Pathological Diagnosis Committee. Among the 36 patients with PTCL and CTCL, objective response rate based on the independent review was 36% (41% and 31%, respectively). The median progression-free survival was 3.1 months (2.1 months in PTCL and 4.2 months in CTCL). The common adverse events (AEs) observed were increased aspartate aminotransferase (AST) / alanine aminotransferase (ALT), hypoalbuminemia, lymphopenia, and pyrexia. Our results indicated that a 9 µg/kg/d dose of E7777 shows efficacy and a manageable safety profile in Japanese patients with relapsed or refractory PTCL and CTCL, with clinical activity observed across the range of CD25 expression. The common AEs were manageable, but increase in ALT / AST, hypoalbuminemia, and capillary leak syndrome should be carefully managed during the treatment.

Rebound and overshoot of donor-specific antibodies to human leukocyte antigens (HLA) during desensitization with plasma exchanges in hematopoietic progenitor cell transplantation: A case report.

BACKGROUND: Donor-specific antibodies (DSA) to HLA have been associated with graft loss in hematopoietic progenitor cell (HPC) transplantation. Limited data associate therapeutic plasma exchange (TPE) with desensitization and successful engraftment. We report an attempt of desensitization and observed overshooting of DSA during transplantation. CASE REPORT AND RESULTS: A 27-year-old female with cutaneous T cell lymphoma was scheduled for HPC transplantation from her HLA-haploidentical half-sister, who carried the HLA-DRB1*13:03:01 allele. The patient had the corresponding DSA. Lacking an alternative donor option at the time, we attempted a desensitization approach by immunosuppression with tacrolimus and mycophenolate mofetil (MMF). Unexpectedly, DSA increased from a mean fluorescence intensity (MFI) of 1835 on day -63 to 9008 on day -7. The MFI increased further during 3 TPE procedures and intravenous immunoglobulin (IVIG) until day -1. After transplantation, the DSA remained elevated despite 2 more TPE/IVIG procedures and graft-versus-host disease prophylaxis with high-dose cyclophosphamide, sirolimus, and MMF. Flow cytometric crossmatch, initially negative, turned positive after transplantation. Primary graft failure occurred and was attributed to antibody-mediated rejection. A second transplantation from a 7/8 HLA-matched unrelated donor, not carrying DRB1*13:03 allele, resulted in successful engraftment. CONCLUSION: Unexpected and rapid increases of a DSA can occur despite the use of current desensitization approaches. This is problematic when conditioning has already started, as such increases are unlikely to be overcome by TPE or other interventions for desensitization. Overshoot of DSA in HPC transplantation has rarely been reported. Its cause remains unclear and can include underlying disease, immunotherapy, chemotherapy, or TPE.

CD209+ monocyte-derived myeloid dendritic cells were increased in patients with leukemic cutaneous T-cell lymphoma undergoing extracorporeal photopheresis via the CELLEXTM system.

BACKGROUND/PURPOSE: We previously reported that myeloid dendritic cells (mDC) were increased in patients with leukemic cutaneous T-cell lymphoma (L-CTCL) following extracorporeal photopheresis (ECP) using the Therakos UVAR XTS™ system. We now assessed monocyte-derived mDCs (Mo-DCs) in L-CTCL patients treated with the CELLEXTM photopheresis system. CD209, a transmembrane receptor, was used to define Mo-DCs. METHODS: Peripheral blood samples from baseline pre-ECP and at Day 2, 1 month, 3 months, and 6 months post-ECP were analyzed by flow cytometry for Lin- HLA-DR+ CD123+ plasmacytoid dendritic cells (pDCs), Lin- HLA-DR+ CD11c+ mDCs, and CD209+ mDCs. The expression of CD209 mRNA was assessed by real-time PCR. RESULTS: At baseline, 7 of 19 patients had lower than normal mDCs, and all patients had lower than normal CD209+ mDCs in peripheral blood mononuclear cells (0.005% in patients, n = 19, vs 0.50% in healthy donors, n = 7, P < .0001). The CD209+ mDC numbers only accounted for 3.28% out of total mDCs in patients compared with 66.51% in healthy donors. After treatment, the CD209+ mDC numbers showed increasing trends in patients. The average absolute numbers of CD209+ mDCs went up by 4.8-fold at 3 months (n = 10, P = .103) and by 6.4-fold at 6 months (n = 9, P = .100). CD209 mRNA expression went up in two patients responsive to therapy, parallel to CD209+ mDC numbers. L-CTCL patients achieved 70% overall clinical response rate (7/10) following ECP therapy with the CELLEXTM system. CONCLUSIONS: Our results suggest that the CELLEXTM photopheresis system is effective for treating L-CTCL patients like the UVAR XTS™ system, and in vivo-generated Mo-DCs increase following ECP.

Bexarotene-induced hypothyroidism: Characteristics and therapeutic strategies.

OBJECTIVE: Central hypothyroidism (CH) is a well-known adverse effect of bexarotene treatment for cutaneous T-cell lymphoma (CTCL). While concomitant levothyroxine therapy is recommended in these cases, associations between ethnic variation or susceptibility and bexarotene-induced CH have not yet been reported. This study aimed to characterize the kinetics and dose dependency of bexarotene-induced CH in Japanese patients. DESIGN AND PATIENTS: Sixty-six Japanese patients with CTCL were retrospectively investigated by evaluating thyroid function during the early phase of bexarotene therapy. RESULTS: At one week after bexarotene initiation, TSH and FT4 values significantly declined. However, this effect was not bexarotene dose-dependent at least at the dose of 96-320 mg/m2 . Approximately 1 month later, 61 patients exhibited hypothyroidism at a relatively low dose of bexarotene (average 251 mg/m2 /day). Forty-five study cases showed this effect at 1 week. Simple regression analyses indicated that higher pretreatment TSH values (at a cut-off value of 1.30:73% sensitivity, 57% specificity) or lower normal (within the lower half of the reference range) pretreatment FT4 values (84% sensitivity, 57% specificity) were predictive of hypothyroidism at 1 week. The remaining 21 cases showed euthyroidism at 1 week, at which TSH values may roughly predict their thyroid function at 1 month (at a cut-off value of 0.05:100% sensitivity, 80% specificity). CONCLUSIONS: Preventive treatment with levothyroxine is recommended for Japanese CTCL patients prior to bexarotene therapy. Minimally, it should be considered for patients with a pretreatment TSH above 1.30, a lower normal pretreatment FT4, or a TSH below 0.05 at 1 week.

Low Drosha protein expression in cutaneous T-cell lymphoma is associated with worse disease outcome.

BACKGROUND: Dysregulation of microRNAs (miRNAs) key regulators may contribute to the pathogenesis of malignancies. miRNA machinery genes such Dicer and Drosha have been reported to be biomarkers in different cancer types. OBJECTIVES: We aimed to evaluate Drosha and Dicer protein expression in cutaneous T-cell lymphoma (CTCL). METHODS: We performed Drosha and Dicer immunohistochemistry in 45 patients with mycosis fungoides and subtypes. Drosha and Dicer expression scores were correlated with clinical parameters including disease-specific death (DSD), stage of disease and different laboratory data. Uni- and multivariate statistics were performed. RESULTS: On univariate analysis, elevated serum LDH and low Drosha expression were significantly associated with advanced stage (P = 0.032 and 0.0062, respectively) and lymphoma-specific death (LSD; P = 0.017 and P = 0.005, respectively). Moreover, elevated circulating CD4+/CD26- lymphocytes were significantly associated with advanced stage (P = 0.032) and DSD (P = 0.0098). On multivariate analysis, low Drosha expression remained in the logistic regression model as significant independent predictor for advanced disease stages [P = 0.013; odds ratio: 5 (confidence interval) CI 1.3-19.3]. Moreover, low Drosha expression (P = 0.026) and elevated LDH (P = 0.025) remained as significant independent predictors for DSD with odds ratios of 13.5 (CI 1.3-134.4 and 8.7 CI 1.3-57.2, respectively). CONCLUSIONS: Low Drosha expression is an independent predictor for advanced stage as well as LSD in CTCL patients indicating a tumour suppressor gene function of Drosha in this disorder.

Increased Interleukin-19 Expression in Cutaneous T-cell Lymphoma and Atopic Dermatitis.

Interleukin-19 (IL-19), a pro-inflammatory cytokine known to stimulate the production of T helper type 2 (Th2) cytokines, is induced by IL-17A and highly expressed in the lesional skin of psoriasis and atopic dermatitis (AD). This aim of this study was to investigate whether IL-19 is involved in cutaneous T-cell lym-phoma (CTCL) and AD. IL-19 levels were significantly higher in the sera of patients with AD and those with advanced-stage CTCL than in normal controls, correlating significantly with clinical disease markers. IL-19 mRNA levels in lesional skin of both diseases were significantly elevated. Immunohistochemical staining revealed that IL-19 was expressed in the epidermis of AD skin and CTCL skin. In vitro, IL-17A and IL-4 increased IL-19 mRNA expression in human keratinocytes. Thus, IL-19 was increased in the sera and skin of AD and CTCL. These results suggest that IL-19 is important for bridging Th17 to Th2 in these diseases.

Plasma miR-155, miR-203, and miR-205 are Biomarkers for Monitoring of Primary Cutaneous T-Cell Lymphomas.

Primary cutaneous T-cell lymphomas (CTCL) affect the skin and tend to transform and spread. CTCL involves primarily the Mycosis fungoides (MF) and more aggressive Sezary syndrome (SS). Oncogenic microRNAs (miRs) are stable epigenetic inhibitors often deregulated in the tumour and detectable as biomarkers in non-cellular fractions of peripheral blood. The tumour-specific expression of miR-155, miR-203, and miR-205 was shown to correctly diagnose CTCL. We herein asked whether these microRNAs can be used as plasma biomarkers for clinical CTCL monitoring. Patients with CTCL (n = 10) and controls with non-malignant conditions (n = 11) repeatedly donated plasma samples every ca. five months. MicroRNAs were detected in the plasma samples by specifically-primed RT-PCR followed by multivariate analyses of the miR expression dynamics. We herein established the plasma miR-classifier for detecting CTCL based on the miR-155 upregulation and miR-203/miR-205 downregulation with 100% specificity and 94% sensitivity. The 3-miR-score in the consecutive samples coincided with the clinical outcome of MF and SS patients such as the therapy response or changes in the clinical stage or tumor size. Quantitation of the selected microRNAs in plasma is a specific and straightforward approach for evaluating CTCL outcome representing, thus, a valuable tool for CTCL diagnostics and therapy response monitoring.

Cutaneous T-cell lymphoma (CTCL): Current practices in blood assessment and the utility of T-cell receptor (TCR)-Vß 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-Vß 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-Vß 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-Vß testing should be considered in future diagnostic and staging algorithms.

Evaluation of blood parameters for the monitoring of erythrodermic cutaneous T-cell lymphoma.

BACKGROUND AND OBJECTIVES: Erythrodermic cutaneous T-cell lymphomas are aggressive diseases posing diagnostic and therapeutic challenges. Numerous indicators for confirming diagnosis and disease-monitoring have been proposed. CD26-negativity of peripheral CD4+ T-cells has been reported to have these properties. Our aim was to test, if the CD4(+) T-cell count, fraction of CD26- or CD7-negative CD4+ T-cells during the course of disease are valuable markers to predict therapeutic efficacy or disease progression in relation to changes in skin status. PATIENTS AND METHODS: Retrospective cohort analysis of eleven patients treated at a tertiary referral centre. Statistics were done by linear regression analysis and logrank test. RESULTS: Five patients displayed response to therapy in the skin, nine in the blood. Patients with cutaneous response showed a decrease of CD4+ T-cells, preceding the clinical response in most patients, whereas the percentage of CD26-negative T-cells changed first during clinical improvement. The calculated positive predictive values for response or progression were low for both CD4-count and CD26-expression. CONCLUSIONS: CD26 is not a reliable marker of either response or progression. As cutaneous response was always associated with a response in blood and not vice versa, we conclude, that the clinical status represents the most important parameter for guiding therapeutic decisions.

Association of nerve growth factor, chemokine (C-C motif) ligands and immunoglobulin E with pruritus in cutaneous T-cell lymphoma.

Many patients with cutaneous T-cell lymphoma (CTCL) experience severe pruritus. This study evaluated serum levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in patients with CTCL. Although serum NGF and BDNF levels in patients with CTCL were not significantly higher than in healthy controls, serum NGF levels in patients with Sézary syndrome were higher than in those with mycosis fungoides and in healthy controls. Enhanced NGF expression by keratinocytes and increased dermal nerve fibres were detected in lesional skin of subjects with Sézary syndrome. Correlations between pruritus in CTCL and serum levels of NGF, BDNF, chemokine (C-C motif) ligand 1 (CCL1), CCL17, CCL26, CCL27, lactate dehydrogenase (LDH), IgE, and soluble interleukin-2 receptor were analysed. Serum CCL1, CCL26, LDH, and IgE levels correlated with pruritus in patients with CTCL. NGF may be associated with increased dermal nerve fibres and pruritus in Sézary syndrome, and CCL1, CCL26, and IgE may be associated with pruritus in CTCL.

Serum soluble CD26 levels: diagnostic efficiency for atopic dermatitis, cutaneous T-cell lymphoma and psoriasis in combination with serum thymus and activation-regulated chemokine levels.

BACKGROUND: CD26 is a multifunctional type II transmembrane glycoprotein, which also exists as a secreted isoform, soluble CD26 (sCD26). The CD26 expression on circulating T cells is decreased in some skin diseases such as cutaneous T-cell lymphoma (CTCL) and psoriasis. It remains to be determined whether sCD26 can be used as a marker of skin diseases or not. OBJECTIVE: To investigate utility of sCD26 as a diagnostic marker of skin diseases in combination with thymus and activation-regulated chemokine (TARC). METHODS: Serum sCD26 levels were measured using enzyme-linked immunosorbent assay in 130 participants including 32 patients with atopic dermatitis (AD); 45 patients with CTCL; 26 patients with psoriasis; and 27 healthy controls. RESULTS: Serum sCD26 levels in patients with CTCL and psoriasis (162.1 ± 80.2 ng/mL and 125.4 ± 82.1 ng/mL respectively) were significantly lower than those of healthy controls (392.6 ± 198.7 ng/mL; P < 0.01 and 0.01 respectively). In patients with CTCL, serum sCD26 levels of patients with advanced stage were 135.0 ± 51.5 ng/mL and they were significantly lower than those with early stage (193.1 ± 96.0 ng/mL; P < 0.05). When we used serum sCD26 and TARC levels for diagnostic criteria, sensitivity, specificity, positive predictive value and negative predictive value for AD, CTCL and psoriasis were 65.2-73.7%, 81.4-97.6%, 65.2-94.4%, and 81.4-88.9% respectively. CONCLUSION: Serum sCD26 levels, combined with serum TARC levels, are helpful in diagnosis of AD, CTCL and psoriasis.

Panniculitis in children.

This paper will give a comprehensive view of the most frequent panniculitides seen in childhood, with emphasis on the types exclusively found in infancy, and for all other types of panniculitides also found in adults. Aim of this paper is also to analyze the clinical differences between panniculitis in childhood and in adulthood, and to give reliable histopathologic criteria for a specific diagnosis. A review of the literature is here integrated by authors' personal contribution. Panniculitides in children is a heterogeneous group of diseases, as well as in adult life, characterized by inflammation of the subcutaneous fat. Only very few types of panniculitis are exclusively found in childhood, such as Sclerema neonatorum and subcutaneous fat necrosis of the newborn, while the vast majority of the other types may be found both in paediatric age and in adults. Furthermore, this paper will consider in detail panniculitis according to their frequency, such as Erythema nodosum, Lupus panniculitis, Cold panniculitis, panniculitis in Behçet disease, and poststeroid panniculitis. It will also describe rare forms of panniculitis, such as Eosinophilic panniculitis (a pathological entity debated by many authors), Subcutaneous panniculitis T-cell lymphoma, and the different forms of the so call "Lipophagic panniculitis", encompassing respectively the febrile relapsing panniculitis of Weber-Christian disease and the non-relapsing form of Rothmann-Makai disease. For each type of panniculitis considered concise information will be given about epidemiology, etiology, clinical findings, laboratory data, prognosis and therapy, while histopathologic findings will be described in detail.

Up-regulation of the chemokine CCL18 by macrophages is a potential immunomodulatory pathway in cutaneous T-cell lymphoma.

Mycosis fungoides (MF) is the most frequent form of cutaneous T-cell lymphoma (CTCL), which can deteriorate from patch stage to dermal-based tumors and systemic involvement in years. The interaction of chemokines in the skin with CTCL cells might have implications for the pathogenesis of the disease. In this study, we show by PCR analysis and immunofluorescence staining that the chemokine CCL18 is present in skin biopsy specimens of patients with MF and its precursor form parapsoriasis en plaque but not in healthy tissue. In addition, the serum levels of CCL18 were increased threefold in MF patients compared with those in healthy controls. In skin, CCL18 was specifically expressed by CD163(+) CD209(+) macrophages at the invasive margin of the tumor and not expressed by mature CD208(+) dendritic cells in the center of the tumor. The chemokine CCL17 was, by contrast, ubiquitously expressed. Furthermore, CCL18 promoted the chemotaxis but not the proliferation of CTCL cells. CCL18 inhibited proliferation of tumor cells and abolished the CXCL12-induced growth of a CTCL cell line. These data link the increased expression of CCL18 with CTCL and suggest an immunomodulatory effect of the chemokine in the pathogenesis of CTCL.

Activation of coagulation in bullous pemphigoid and other eosinophil-related inflammatory skin diseases.

Bullous pemphigoid (BP) is a skin disease caused by autoantibodies to hemidesmosomal proteins BP180 and BP230, with eosinophils participating in blister formation. Tissue factor (TF), the initiator of coagulation, is embodied within the eosinophil granules and exposed upon activation. We evaluated the coagulation activation in patients with BP (63), chronic urticaria (CU; 20), atopic dermatitis (AD; 14), cutaneous drug reactions (CDRs; six), psoriasis (20), dermatitis herpetiformis (DH; four) and primary cutaneous T cell lymphoma (CTCL; five), and in 40 healthy controls. Prothrombin fragment F1+2 and d-dimer (coagulation markers) were measured by enzyme-linked immunosorbent assay (ELISA) in all plasma samples and BP blister fluid. Skin TF expression was evaluated immunohistochemically in the patients and 20 controls. F1+2 and d-dimer levels were higher in BP plasma than in control plasma (P = 0·0001 for both), and dramatically high in blister fluid; both correlated positively with disease severity, esinophil counts and anti-BP180 antibodies (P = 0·006-0·0001). Plasma F1+2 and d-dimer levels were higher in the CU, AD and CDR patients than in controls (P = 0·0001 for all), but normal in the psoriasis, DH and CTCL patients. Skin TF was expressed in the BP (P = 0·0001), CU (P = 0·0001), AD (P = 0·001) and CDR patients (P = 0·01), but not in the psoriasis, DH or CTCL patients. Co-localization confocal microscopy studies confirmed eosinophils as the source of TF in 10 BP patients. The coagulation cascade is activated in BP and other eosinophil-mediated skin disorders, but not in non-eosinophil driven conditions. This hypercoagulability may contribute to inflammation, tissue damage and, possibly, thrombotic risk.

Utility of flow cytometry and gene rearrangement analysis in tissue and blood of patients with suspected cutaneous T­cell lymphoma.

Cutaneous T­cell lymphoma (CTCL) is difficult to diagnose at an early stage. Current diagnostic tools include clinical examination, histomorphologic analysis, immunohistochemistry, flow cytometry of peripheral blood and/or lesional tissue, and evaluation of T­cell receptor (TCR) clonality by gene rearrangement analysis (TCRGR). Advances in genomic sequencing, including high­throughput sequencing (HTS), can be used to identify specific clones of rearranged TCR genes. Even with all of these tools, CTCL can take as long as a decade to definitively diagnose, potentially delaying treatment options and causing patient anxiety. This study aimed to evaluate the performance of the various ancillary testing modalities used to diagnose early­stage CTCL. In a subset of patients the performance of HTS was compared to flow cytometry and conventional TCRGR analysis via polymerase chain reaction (PCR). Fifty­five patients, with a total of 68 skin biopsies and peripheral blood draws, were evaluated using flow cytometry, PCR­TCRGR, and HTS­TCRGR to determine the sensitivity and specificity of each ancillary test. In tissue biopsies, flow cytometry (64%), PCR (71%) and HTS (69%) shared similar sensitivities; flow cytometry had the highest specificity (93%), followed by HTS (86%) and PCR (76.9%). However, flow cytometry and PCR had insufficient DNA quantities in 29 and 15% of the specimens, respectively. Peripheral blood testing was less sensitive than tissue testing (flow cytometry 14%, PCR 41%, HTS 33%); in peripheral blood, HTS was the most specific test (flow cytometry, 70%; PCR, 62.5%; and HTS, 100%). HTS is a highly specific molecular test for identifying CTCL in peripheral blood and skin biopsy specimens; however, our findings suggest a need for a continued search for more sensitive tests for early­stage CTCL.

Determining the immune environment of cutaneous T-cell lymphoma lesions through the assessment of lesional blood drops.

Detailed analysis of the cells that infiltrate lesional skin cannot be performed in skin biopsy specimens using immunohistochemistry or cell separation techniques because enzyme treatments applied during the isolation step can destroy small amounts of protein and minor cell populations in the biopsy specimen. Here, we describe a method for isolating T cells from drops of whole blood obtained from lesions during skin biopsy in patients with cutaneous T-cell lymphoma. Lesional blood is assumed to contain lesional resident cells, cells from capillary vessels, and blood overflowing from capillary vessels into the lesion area. The lesional blood showed substantial increases in distinct cell populations, chemokines, and the expression of various genes. The proportion of CD8+CD45RO+ T cells in the lesional blood negatively correlated with the modified severity-weighted assessment tool scores. CD4+CD45RO+ T cells in the lesional blood expressed genes associated with the development of cancer and progression of cutaneous T-cell lymphoma. In addition, CD8+CD45RO+ T cells in lesional blood had unique T-cell receptor repertoires in lesions of each stage. Assessment of lesional blood drops might provide new insight into the pathogenesis of mycosis fungoides and facilitate evaluation of the treatment efficacy for mycosis fungoides as well as other skin inflammatory diseases.

Utility of TRBC1 Expression in the Diagnosis of Peripheral Blood Involvement by Cutaneous T-Cell Lymphoma.

Peripheral blood involvement by cutaneous T-cell lymphoma is typically assessed by flow cytometry and plays a critical role in diagnosis, classification, and prognosis. Simplified strategies to detect tumor cells (Sezary cells) fail to exclude reactive subsets, whereas tumor-specific abnormalities are subtle and inconsistently present. We implemented a flow cytometric strategy to detect clonal Sezary cells based on the monotypic expression of one of two mutually exclusive TCR constant ß chains, TRBC1 and TRBC2. Analysis of CD4+ T-cell subsets and TCR variable ß classes from healthy donors showed polytypic TRBC1 staining. Clonal Sezary cells were identified by TRBC1 staining in 56 of 111 (50%) samples from patients with cutaneous T-cell lymphoma, accounting for 7-18,155 cells/µl and including 13 cases (23%) lacking tumor-specific immunophenotypic abnormalities. CD4+ T-cell subsets from 86 patients without T-cell lymphoma showed polytypic TRBC1 staining, except for five patients (6%) with minute T-cell clones of uncertain significance accounting for 53-136 cells/µl. Assessment of TRBC1 expression within a comprehensive single-tube flow cytometry assay effectively overcomes interpretative uncertainties in the identification of Sezary cells without the need for a separate T-cell clonality assay.