Absence of modulation of CD4+CD25high regulatory T cells in CTCL patients treated with bexarotene

Please cite this paper as: Absence of modulation of CD4+CD25^high regulatory T cells in CTCL patients treated with bexarotene. Experimental Dermatology 2010; 19 : e95–e102. Abstract: Cutaneous T‐cell lymphoma (CTCL) are a heterogeneous group of lymphoproliferative disorders, characterized by the infiltration of the epidermis by mature and activated malignant CD4+ T‐lymphocytes. Retinoids such as retinoic acid and synthetic analogues have long been used alone or in combination with other therapies for CTCL. Bexarotene, the first synthetic highly selective RXR retinoid, was approved for the treatment of all stages of CTCL in patients refractory to at least one systemic therapy. Recently, six cases in which the initiation of bexarotene therapy for CTCL was associated with the progression of internal disease despite improvement of cutaneous signs and symptoms were reported. Moreover, it has been established that retinoids promote the generation of CD4+ Foxp3+ regulatory T cells, raising the question of an induction of regulatory T‐cells by bexarotene. The aim of this work was to determine if bexarotene induces an increase of functional regulatory T cells which could play a role in the development of secondary extra‐cutaneous lymphomas. Regulatory T cells were studied both in cutaneous biopsy specimens using an immunohistochemical analysis of CD4, CD25 and Foxp3 and in blood where proportion and functionality of circulating CD4+CD25^high T‐cells were determined. The study was performed in 10 patients [five patients with Sézary syndrome (SS) and five mycosis fungoïdes (MF)], treated for 6 months with bexarotene. Four healthy donors were used as controls for phenotypic and functional analysis on PBL. We found that the frequency of CD4+CD25^high Treg cells was not significantly different before starting bexarotene and after 6 months of treatment in CTCL patients. However, we observed that the frequency of CD4+CD25^high Treg cells before the beginning of the treatment was significantly increased compared to healthy donors. In addition, functional assays demonstrated that Foxp3 expressing CD4+CD25^high T‐cells were capable of suppressing autologous CD4 + CD25? T‐cell proliferation. In the present work, we detected the presence of functional circulating CD4+CD25^high Foxp3+ regulatory T‐cells in CTCL patients, with an increased frequency compared to healthy donors. The treatment with bexarotene does not seem to affect the regulatory T‐cell compartment.     

Oral bexarotene for post‐transplant cutaneous T‐cell lymphoma

Organ transplant recipients receiving immunosuppression have an increased risk of developing post‐transplant lymphoproliferative diseases (PTLDs). Traditionally, PTLDs refer to Epstein‐Barr virus (EBV)‐induced B‐cell lymphoma. However, post‐transplant T‐cell lymphoma may also occur and tends to have a poorer response to reduced immunosuppressive therapy. As such, additional therapy is often needed for post‐transplant T‐cell lymphoma, including post‐transplant cutaneous T‐cell lymphoma (PT‐CTCL). We present only the third case of PT‐CTCL occurring after liver transplantation. The patient was diagnosed with stage IB mycosis fungoides (MF). His lesions were refractory to multiple skin‐directed therapies, and so he was given oral bexarotene 150 mg daily and his oral tacrolimus dose was decreased to 2 mg daily. Remarkably, his MF patches have demonstrated a complete response to oral bexarotene 75 mg daily without recurrence over 11 years of follow‐up. He developed hypertriglyceridemia with bexarotene 150 mg, so his dose was decreased to 75 mg, without loss of response. Our report is the second to describe PT‐CTCL demonstrating a long‐term complete response to oral bexarotene. Given its anti‐carcinogenic properties and favorable toxicity profile, oral bexarotene represents an appealing treatment option for PT‐CTCL refractory to skin‐directed therapies.     

Phase I/II study of the oral retinoid X receptor agonist bexarotene in Japanese patients with cutaneous T‐cell lymphomas

Safety, tolerability, pharmacokinetics and efficacy of bexarotene, a novel retinoid X receptor (RXR)‐selective retinoid, were evaluated in Japanese patients with stage IIB–IVB and relapsed/refractory stage IB–IIA cutaneous T‐cell lymphomas (CTCL). This study was conducted as a multicenter, open‐label, historically controlled, single‐arm phase I/II study. Bexarotene was p.o. administrated once daily at a dose of 300 mg/m² for 24 weeks in 13 patients, following an evaluation of safety and tolerability for 4 weeks at a dose of 150 mg/m² in three patients. Eight of 13 patients (61.5%) with an initial dose of 300 mg/m² met the response criteria using the modified severity‐weighted assessment tool (mSWAT) at 24 weeks or discontinuation. Dose‐limiting toxic effects (DLT) were present in four of 13 patients (31%) at a dose of 300 mg/m²: two neutropenia, one abnormal hepatic function and one hypertriglyceridemia. No DLT was observed in patients received 150 mg/m² bexarotene. In the 13 patients at 300 mg/m², common drug‐related adverse events (AE) included hypothyroidism (92%), hypercholesterolemia (77%), leukopenia or neutropenia (39%), nasopharyngitis or anemia (31%). The treatment‐related grade 3 AE included hypertriglyceridemia (4/16 patients, 25%), increased alanine aminotransferase, increased aspartate aminotransferase, dyslipidaemia, leukopenia and neutropenia (1/16 patients, 6%), and one of 16 patients experienced grade 4 hypertriglyceridemia. No patients discontinued bexarotene due to the AE during the study, but dose reduction or suspension was required. Bexarotene was shown to be well tolerated at 300 mg/m² once daily and effective in Japanese patients with CTCL.     

Efficacy and safety of bexarotene combined with photo(chemo)therapy for cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a chronic condition with low malignancy. International treatment guidelines for CTCL are widely followed in Europe and the USA. Combination therapy with therapeutic agents for CTCL and phototherapy is effective on the basis of European data. The efficacy and safety of combination therapy for Japanese CTCL patients are not established. We investigated the efficacy and safety of combination therapy with photo(chemo)therapy and bexarotene in Japanese CTCL patients. Twenty-five patients received daily oral bexarotene (300 mg/m² body surface), followed by bath-psoralen plus ultraviolet (UV)-A (PUVA) or narrowband UV-B. Treatment results were evaluated using the modified Severity-Weighted Assessment Tool (mSWAT) and the Physician Global Assessment of Clinical Condition (PGA) up to week 24. Safety was also assessed. Twenty-four weeks after initiating treatment, the total response rate was 80.0% (mSWAT) and 84.0% (PGA). Response rates did not differ when stratified by disease stage. Number of days (mean ± standard deviation) for time to response, duration of response and time to progression determined by the mSWAT were 20.7 ± 9.62, 117.0 ± 43.0 and 163.6 ± 28.8, respectively. T-helper 2 chemokine levels in patients at stage IIA or more decreased significantly at weeks 12 and 24. All patients experienced adverse events and adverse drug reactions. Serious adverse drug reactions included sepsis, anemia and congestive cardiac insufficiency (n = 1 each). Other adverse drug reactions were of mild to moderate severity. Combination therapy with bexarotene and PUVA was safe and effective in Japanese CTCL patients.     

The optimal use of bexarotene in cutaneous T-cell lymphoma

The management goal in cutaneous T-cell lymphomas (CTCLs) is to improve symptoms and induce remission. Early-stage disease is generally treated with skin-directed therapies. However, if these do not control the disease, systemic therapy becomes necessary. Bexarotene, a novel rexinoid, is an oral, noncytotoxic drug that has been approved in Europe for the treatment of refractory advanced-stage CTCL and in the U.S.A. for refractory CTCL. We provide guidance on the use of bexarotene in the management of CTCL, based on data from phase II/III clinical trials and the authors' clinical experience, and suggest how the potential of the drug can be maximized. The clinical trial results with bexarotene are reviewed, especially in comparison with interferon-alpha, which is the other commonly used noncytotoxic systemic therapy for CTCL. A treatment algorithm for bexarotene in refractory CTCL is suggested. As bexarotene may take time to achieve a maximum response, this algorithm recommends that therapy should be continued for a sufficient period to allow for a delayed onset of action. In addition, possible combination therapies with bexarotene are discussed. We conclude that bexarotene is effective in the management of CTCL, and has the advantage of oral administration. An on-going randomized clinical trial comparing psoralen plus ultraviolet A (PUVA) with PUVA plus bexarotene will provide valuable information about this combination regimen in early-stage disease, but further data are needed on the relative efficacies of other combination therapies with bexarotene in CTCL.     

Long‐term efficacy and safety of bexarotene for Japanese patients with cutaneous T‐cell lymphoma: The results of a phase 2 study (B‐1201)

The present study (B‐1201 clinical trial) was conducted as a multicenter, open‐label, single‐arm phase II study to evaluate the long‐term safety, tolerability and efficacy of bexarotene. This study enrolled 10 Japanese adults aged more than 20 years with cutaneous T‐cell lymphoma (CTCL) who completed the 24‐week study period of the B‐1101 trial. The objective response rate (ORR) was 53.8% (95% confidence interval, 25.1–80.8). In the early stage (IB), the ORR was 60% (3/5 cases). In the advanced stage (IIB and IIIA), the ORR was 57.1% (4/7 cases). The median time to response was 58 days (range, 27–168). The median treatment duration was 380 days (range, 33–1674). The median duration of response (DOR) could not be reached during the study period. The longest DOR reached 1618 days at the end of the B‐1201 trial. Nine patients (56.3%) in the full analysis set (FAS) population experienced dose reduction of bexarotene. Common drug‐related adverse events in the FAS population included hypothyroidism (93.8%), hypertriglyceridemia (81.3%), hypercholesterolemia (81.3%), leukopenia (68.8%) and neutropenia (56.3%). Dose‐limiting toxicity (DLT) was present in five (38.5%) of the 13 patients in the 300 mg/m² cohort. Of the five patients, four developed grade 3 neutropenia and one developed grade 4 hypertriglyceridemia. All DLT cases recovered after the discontinuation of bexarotene. None of the five patients discontinued this trial because of DLT. The B‐1201 trial shows the long‐term safety of oral bexarotene for Japanese patients with CTCL, despite frequent dose reduction.     

Bexarotene – an alternative therapy for progressive cutaneous T‐cell lymphoma? First experiences

Background: A standard therapy for advanced cutaneous T‐cell lymphomas has not yet been defined. Bexarotene is a new retinoid x receptor‐specific retinoid that has been approved for systemic second‐line therapy for cutaneous T‐cell lymphomas in the USA and Europe. In order to evaluate the efficacy of bexarotene in cutaneous T‐cell lymphomas, a pilot trial was initiated. Patients and methods: In a pilot project 10 patients with advanced cutaneous T‐cell lymphomas, who had received a variety of previous treatments, were treated with bexarotene at the departments of dermatology in Münster, Minden and Charité Berlin, Germany. The patients received bexarotene at a dose of 300 mg/m² body surface daily. According to the percentage of tumour reduction and affected body surface, the response rates were divided in complete and partial remission, stable disease and progressive disease. Laboratory parameters i. e. cholesterol, triglycerides transaminases, T3, T4, and TSH were screened regularly. Results: In 2 patients a short partial remission was achieved; however, after a few weeks progression followed. In 4 patients a lasting stabilisation was obtained. The other 4 patients showed a progressive disease during therapy. 6 patients developed hypertriglyceridemia with levels up to 2000 mg/dl; therapy had to be suspended in 3 patients because of these adverse drug events. Conclusion: Weighing benefits and risks, bexarotene can at present not be recommended as standard therapy in the treatment of patients with progressive cutaneous lymphomas.     

Primary cutaneous CD20-positive T-cell lymphoma

CD20 is a transmembrane protein that is expressed by B cells during their development and is, therefore, commonly used to label cells of B lineage in lymphoid infiltrates. CD20-positive T-cell lymphoma is infrequent but well recognized. Cases reported in the literature show a variety of clinical and histoimmunochemical profiles. Primary cutaneous CD20-positive T-cell lymphoma is vanishingly rare; only eight cases have been previously reported. We present two new cases of this entity and describe their clinical, histological and immunohistochemical features. CD20 is a highly specific B-cell marker. However, it has been reported in a subset of normal T-cells in peripheral blood and bone marrow of healthy individuals. This subset of T-cells also expresses more often CD8 and g/d than the CD20-negative T-cells. Two main theories have been postulated to explain the expression of CD20 by neoplastic T-cells. The first possibility is that these lymphomas develop from the CD20-positive subset of normal T-cells. The second theory regards CD20 as an activation marker. Prognostic implications and therapeutic options of T-cell lymphomas with positivity for CD20 remain to be elucidated.     

ALK‐positive primary cutaneous T‐cell‐lymphoma (CTCL) with unusual clinical presentation and aggressive course

Anaplastic lymphoma kinase (ALK) expression is uncommon in primary cutaneous T‐cell‐lymphomas (CTCL). We report the case of a patient who was initially diagnosed with small plaque parapsoriasis, and eventually developed an unusual manifestation of CTCL 6 years later. The disease was characterized by aggressively ulcerating plaques and tumors of the entire skin. Histopathology revealed monoclonal proliferation of atypical T‐lymphocytes and CD30‐positive blasts with expression of ALK and identification of an ATIC‐ALK fusion protein. Extensive staging confirmed the primary cutaneous origin of the lymphoma. After failure of several conventional treatments including polychemotherapy, the patient finally achieved remission after receiving brentuximab‐vedotin, alemtuzumab and subsequent allogeneic stem cell transplantation. In the following, the patient developed inflammatory cutaneous lesions that pathologically showed no evidence for lymphoma relapse or classical cutaneous graft‐versus‐host disease. The patient responded to immunosuppression, but finally died from multi‐organ failure due to sepsis 8 months after stem cell transplantation. This is a rare instance of ALK positivity in a CTCL, most likely resembling CD30+ transformed mycosis fungoides, because it was not typical for cutaneous anaplastic large cell lymphoma (ALCL). In contrast to its role in systemic ALCL as favorable prognostic marker, ALK expression here was associated with an aggressive course.     

Distinct age‐matched serum biomarker profiles in patients with cutaneous T‐cell lymphoma

Immunological functions decline with age. Because MS/SzS predominately affects the elderly, it is important to distinguish age‐related from cancer‐specific changes. Also, MF and SzS are malignancies of CD4⁺ T‐lymphocytes, further compromising an immune state of the patients. The objectives of this study were to distinguish disease‐specific immunological deterioration by performing comparative age ‐ matched Luminex multiplex assessment of 34 serum biomarkers between patients with MF/SzS, HIV‐infected individuals and normal controls. Controlling for age, expression level appears to significantly differ between patients with MF/SzS and controls for the following biomarkers: G‐CSF, IL‐5, MIP‐1β, TNF‐α, VEGF, EOTAXIN, IL‐8, IL‐12, IL‐2R, IP10, MCP‐1, MIG, TNFR1 and TNFR2 (P < 0.05), while others showed normal age‐related changes. Interestingly, cluster analysis placed MF/SzS profiles closer to HIV. This further underscores an immunologically compromised state of patients with MF/SzS and suggests its potential self‐perpetuating role in disease progression.     

Retrospective analysis of 133 patients with cutaneous lymphomas from a single Japanese medical center between 1995 and 2008

In 2008, a revised World Health Organization (WHO) system of hematological neoplasm classification was promulgated. Between January 1995 and December 2008, 133 new patients with cutaneous lymphomas were seen at the dermatology clinic of Okayama University Hospital. All patients were re-classified according to the revised WHO system. The incidence rates were analyzed and the survival was estimated. Of 133 patients, 106 (79.7%) had primary cutaneous lymphomas (PCLs) and 27 (20.3%) were skin invasion from extracutaneous origin of systemic lymphoma. Compared with several reports from western countries, "mature T-cell and NK-cell neoplasms" was frequent in this study (87% vs. 77 or 72%) because of the occurrence of adult T-cell leukemia/lymphoma (ATLL) and "extranodal NK/T cell lymphoma, nasal type", with less frequent occurrence of "mature B-cell neoplasms" (13% vs. 23 or 28%). Estimated survival of patients with mycosis fungoides was favorable (5-year survival rate 90.6%), but that of the patients with primary cutaneous anaplastic large cell lymphoma (C-ALCL) was extremely less favorable than previously reported (5-year survival rate of 47.4%).     

Decreased interleukin‐21 expression in skin and blood in advanced mycosis fungoides

Interleukin (IL)‐21 is regarded as a potent antitumor agent, which increases the cytotoxicity of both natural killer (NK) and CD8⁺ T cells. In this study, we investigated the role of IL‐21 in mycosis fungoides (MF). IL‐21 mRNA expression levels in patch and plaque MF were significantly higher than those in normal skin. IL‐21 mRNA expression levels in tumor MF were significantly decreased compared with those in patch and plaque MF. Interestingly, mRNA expression levels of IL‐21 in MF lesional skin significantly correlated with those of T‐helper type‐1 cytokines/chemokines such as CXCL10, CXCL11 and γ‐interferon. Immunohistochemistry showed that IL‐21 was expressed by keratinocytes in patch and plaque MF. Furthermore, serum IL‐21 levels in patients with tumor MF were significantly lower than those of healthy controls and plaque MF. Thus, IL‐21 expression was significantly downregulated in skin and blood of patients with tumor MF, which may contribute to progression of MF. Our study suggests that recombinant IL‐21 would be a promising therapy for MF.     

Case of primary cutaneous peripheral T‐cell lymphoma,not otherwise specified,with characteristics of follicular helper T cells

We report a case of an 88‐year‐old woman with a decalvant, erythematous, ulcerated tumor extending from the right temporal to occipital region. Histopathological analysis revealed a dense infiltration of medium‐to‐large‐sized atypical cells throughout the entire dermis. The result of immunohistochemical analysis showed that the infiltrating T cells expressed programmed death‐1 (PD‐1), Bcl‐6 and CXCL13. Flow cytometry analysis showed that CD4⁺ PD‐1^hi T cells also expressed CD10, inducible T‐cell co‐stimulator and CXCR5. On the basis of the clinical appearance and the histopathological findings, we diagnosed the patient with primary cutaneous peripheral T‐cell lymphoma, not otherwise specified. Recently, the concept of primary cutaneous follicular helper T (TFH)‐cell lymphoma was proposed, and in this case, tumor cells clearly expressed TFH‐cell markers. Therefore, we considered this case to be a variant of the entity. Although this entity is still provisional, this case supports the new concept.     

Extrafacial indolent CD8‐positive cutaneous lymphoid proliferation with unusual symmetrical presentation involving both feet

Indolent CD8+ cutaneous lymphoid proliferation represents a recently described entity among cutaneous T‐cell lymphomas that typically presents with solitary skin lesions on the face or at acral sites and usually follows an indolent clinical course. Histopathologically, this entity is characterized by a dense dermal infiltrate of non‐epidermotropic, small‐ to medium‐sized pleomorphic CD8+ T‐cells of the non‐activated cytotoxic phenotype showing a clear‐cut grenz zone and a low proliferation index. Distinction from otherwise aggressive T‐cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental. We herein present an unusual case of indolent CD8+ cutaneous lymphoid proliferation presenting in bilateral symmetrical distribution on both feet and lacking the otherwise described grenz zone. Our case widens the spectrum of possible clinical and histomorphological variations of this entity. Taking into account the distinctive and unique clinical and microscopic features of all hitherto published cases of indolent CD8+ cutaneous lymphoid proliferation we suppose that this lymphoma subtype has to be included as a new and distinct entity in the World Health Organisation (WHO)‐/European Organisation for Research and Treatment of Cancer (EORTC)‐classification of cutaneous lymphomas.     

Primary cutaneous follicular helper T‐cell lymphoma: diagnostic pitfalls of this new lymphoma subtype

The recently proposed entity of cutaneous follicular helper T (T_FH) cell lymphoma (CT_FHCL) harbors distinct clinical and histopathologic features. Here, diagnostic pitfalls are exemplified in a case report and by review of the literature. A 45‐year‐old patient developed rapidly growing nodules and plaques on upper arms and buttocks, which were initially misdiagnosed as primary cutaneous follicle center B‐cell lymphoma (CFCL). Consequently, systemic therapy with rituximab failed and consecutive skin biopsies revealed CT_FHCL (CD3+CD4+CD10+PD‐1+bcl6+ICOS+CXCL13+). Interestingly, the prima vista PD‐1‐positive and CD10‐positive tumor cells lost PD‐1 expression in follow‐up biopsies while retaining CD10, ICOS and CXCL13 expression. All biopsy specimens displayed an identical clonal T‐cell population. Initially, nodules were controlled by local radiotherapy and oral psoralen combined with ultraviolet A (PUVA) therapy. However, disease recurred and progressed rapidly with disseminated nodules. Treatment with bexarotene, methotrexate and polychemotherapy failed to stop disease progression. Finally, modified total skin electron beam radiation resulted in complete remission. Disease stabilized on maintenance therapy with bexarotene in combination with ultraviolet A (UVA) therapy. The case highlights that because of concomitant B‐cell stimulation, CT_FHCL clinicopathologically is prone to be mistaken for CFCL. Importantly, CT_FHCL might lose PD‐1 while retaining CD10 expression in later stages, which may lead to confusion in distinguishing CT_FHCL from CFCL.     

Relief of intractable pruritus with romidepsin in patients with cutaneous T‐cell lymphoma: A series of four cases

Cutaneous T‐cell lymphomas (CTCL) are a relatively rare and heterogeneous group of non‐Hodgkin lymphomas that typically present in the skin. The majority of patients with CTCL experience pruritus, which can interfere with daily activities, significantly impact quality of life, and is typically uncontrolled by standard anti‐itch therapies. Several lymphoma treatments have reported anti‐pruritic effects including romidepsin, a potent class 1 selective histone deacetylase inhibitor approved for the treatment of patients with CTCL who have had at least one prior systemic therapy. Here, we describe the cases of four patients with debilitating and refractory pruritus that were resolved with romidepsin. Resolution of pruritus was observed in both clinical responders and nonresponders, and dose modification was used successfully to manage adverse events and for maintenance treatment. The potential for pruritus relief with romidepsin should be considered when treating patients with CTCL.     

Regression of extranodal natural killer/T-cell lymphoma, nasal type with denileukin diftitox (Ontak) and bexarotene (Targretin): report of a case

Denileukin diftitox (Ontak) is a fusion protein comprising a diphtheria toxin and an interleukin (IL)-2 moiety that specifically targets CD25 (IL-2 receptor)-positive tumour cells. We report a patient with rapidly progressive Epstein-Barr virus-positive nasal type extranodal natural killer/T-cell lymphoma (extranodal NKTCL), treated with a combination of denileukin diftitox (Ontak) and oral bexarotene (Targretin). A significant regression of the cutaneous tumours was observed already after the first cycle of denileukin diftitox and was maintained for a period of 5 months with monthly cycles of denileukin diftitox. The treatment was well tolerated. Following this response the patient decided to stop the treatment. He was then followed by his oncologist and lost from dermatological follow-up. Shortly after treatment withdrawal the disease progressed and the patient received one cycle of doxorubicin (Caelyx). He died from septic shock syndrome 2 months later. To our knowledge this is the first case of extranodal NKTCL treated with denileukin diftitox and bexarotene. A striking, albeit transient, response occurred with this therapy. Combination treatment with denileukin diftitox and bexarotene should be further assessed in this aggressive type of cutaneous lymphoma.     

皮肤T细胞淋巴瘤并发原发性皮肤曲霉病1例

报道1例皮肤T细胞淋巴瘤患者并发上曲霉引起的原发性皮肤曲霉病，患者女性，41岁，左胫前2处相连的巨大黑痂，刮取物直接镜检有透明的分枝分隔菌丝，组织病理检查见较多粗细均匀的有隔菌丝，菌丝呈Y型分枝，菌种鉴定为土曲霉。     

Gamma‐delta T‐cell lymphoma arising in a long‐standing cutaneous plaque

The precise classification and characterization of primary cutaneous gamma‐delta T‐cell lymphoma (PCGD‐TCL) has been hindered by clinical and morphologic features that overlap with other lymphomas, especially subcutaneous panniculitis‐like T cell lymphoma (SPTCL). The recent World Health Organization/European Organization for Research and Treatment of Cancer (WHO/EORTC) classification distinguishes the more aggressive PCGD‐TCL from the usually indolent SPTCL, however. We report a 30‐year‐old woman with an indurated violaceous plaque on the left cheek that had been present for several years. Biopsies showed a dense lymphocytic infiltrate involving the subcutis and dermis that consisted mostly of small and medium‐sized lymphocytes, some with irregular nuclear contours and dense chromatin. These cells were positive for TIA‐1, TCR‐gamma and CD8, but negative for beta‐F1 and granzyme‐B. Staging with positron emission tomography–computed tomography (PET/CT), CBC and bone marrow with flow cytometry identified lymphadenopathy as well as blood and marrow involvement by an abnormal TCRgd‐positive T‐cell proliferation (Ann Arbor Stage IV). The patient's history of a long‐standing lesion in this case is unusual, in that gamma‐delta T‐cell lymphomas are typically rapidly progressive neoplasms. As such, it raises the possibility of ‘transformation’ of a long‐standing inflammatory process into an overt lymphoma.     

Malignant T cells in cutaneous T‐cell lymphoma lesions contain decreased levels of the antiapoptotic protein Ku70

Background Malignant T cells in primary cutaneous T‐cell lymphoma (CTCL) are genetically unstable and exhibit prolonged lifespans potentially explained by dysregulation of apoptosis, yet are responsive to apoptosis‐inducing therapies. The heterodimeric protein Ku70/80 is known to play a role in DNA repair (Ku70 and Ku80) and inhibition of apoptosis (Ku70 only). Objectives To investigate the expression of Ku70/80 in CD3+ T cells derived from skin and blood in patients with CTCL and normal samples, as well as benign dermatoses. Methods Normal (n = 10), CTCL (n = 9) and benign dermatoses (n = 13) skin samples were stained for confocal imaging of Ku70/80 and CD3 and analysed using imaging software. Circulating CD4+ T cells in normal and CTCL peripheral blood were analysed by flow cytometry and Western blot for Ku70/80 expression (n = 6). Results Ku70 and Ku80 were significantly diminished in T cells of CTCL lesions relative to T cells of control skin. Decreased T‐cell Ku70 expression was not a feature of the benign dermatoses psoriasis and contact dermatitis, suggesting that loss of Ku70/80 in CTCL is not simply the result of cutaneous inflammation. Reduced Ku70 was also noted in circulating CD4+ T cells in patients with CTCL with peripheral blood involvement. Conclusions Deficient expression or lack of Ku70/80 may result in genomic instability and play a role in tumorigenesis, as well as account for the increased susceptibility of malignant T cells to apoptosis‐inducing treatment modalities in the setting of intrinsic resistance to apoptosis.