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Background: Our objective was to describe the clinical, histological characteristics, and disease outcome of a cohort of mycosis fungoides (MF) diagnosed during childhood including disease status at adulthood. Methods: This is a retrospective multicentre survey of patients aged under 18 years at diagnosis with histologically confirmed MF. Patients’ clinical and histological characteristics, treatments, and disease outcome (for patients followed for more than 12 months) were analysed. Results: Forty-six patients were included (median age at diagnosis: 11 years; M:F sex ratio: 3:1) with 39 (85%) followed for at least 12 months. Thirty-nine patients (85%) had stage I MF. Hypopigmented patches were observed in 48% and folliculotropism in 43% patients. Immunophenotype of the skin infiltrate was predominantly CD8+ in 17% of patients. Initial management included a wait-and-see strategy in 6/39 (15%), skin-directed treatment in 27 (69%), and systemic treatment in 6 (15%) patients, respectively, with partial or complete clinical response (PR or CR) observed in 28 patients (72%). 14/39 patients (36%) relapsed after initial response. After a median follow-up period of 54 months, disease status at last news was PR or CR in 31/39 (79%), stable disease in 6 (15%), and progression in 2 (5%) patients. Histological transformation was observed in 3/39 (8%). Of the 15 patients followed until adulthood, 13 (87%) had persistent MF. Discussion: This survey confirms the high frequency of hypopigmented and folliculotropic lesions and of CD8+ immunophenotype compared to adult MF patients. The long-term course is usually indolent but transformation may occur sometimes long after disease onset and the disease may persist during adulthood.

Primary cutaneous diffuse large B-cell lymphoma, leg-type (PCDLBCL-LT) is an aggressive cutaneous lymphoma. Bone involvement is rare and poorly described. We present five cases of PCDLBCL-LT with bone localization. In four cases, the bone involvement was diagnosed during the initial staging with positron emission tomography (PET) or computed tomography (CT) scan, and in the fifth case after tibial fracture during treatment with rituximab (RTX) and polychemotherapy (PCT). PCDLBCL-LT can be asymptomatic and involve bone sites distant from cutaneous lesions. None had other extracutaneous involvement. In our series, all patients received RTX-PCT as first-line chemotherapy and all had early relapses or progression. Second-line treatments had poor efficacy. Our series shows that bone involvement seems to be associated with poor prognosis in PCDLBCL-LT. Bone localization is not diagnosed with initial thoracic–abdominal–pelvic CT when asymptomatic and affecting the limbs only. If there is a suspicion of PCDLBCL-LT, patients should undergo systematic investigation with alternative imaging techniques, including PET, both at baseline and if there is any concern during follow-up.

International audience; No abstract available

International audience

Sézary syndrome (SS) is an aggressive cutaneous T cell lymphoma with poor prognosis mainly characterized by the expansion of a tumor CD4+ T cell clone in both skin and blood. So far, the development of new therapeutic strategies has been hindered by a lack of reproducible in vivo models closely reflecting patients’ clinical features. We developed an SS murine model consisting of the intravenous injection of Sézary patients’ PBMC, together with a mixture of interleukins, in NOD-SCID-gamma mice. Thirty-four to fifty days after injection, mice showed skin disorders similar to that observed in patients, with the detection of epidermis thickening and dermal tumor T cell infiltrates. Although experimental variability was observed, Sézary cells could be tracked in the blood stream, confirming that our model could efficiently exhibit both skin and blood involvement. Using this model, we evaluated the therapeutic potential of RT39, a cell-penetrating peptide derived from the survival protein anti-apoptosis clone 11 (AAC-11), that we previously characterized as specifically inducing apoptosis of Sézary patients’ malignant clone ex vivo. Systemic administration of RT39 led to cutaneous tumor T cells depletion, demonstrating efficient malignant cells’ targeting and a favorable safety profile. These preclinical data confirmed that RT39 might be an innovative therapeutic tool for Sézary syndrome.

Background Mogamulizumab is a novel defucosylated monoclonal antibody targeting the C-C chemokine receptor 4 (CCR4) that eradicates Sezary cells via antibody-dependent cellular cytotoxicity. Treatment of Sezary syndrome with mogamulizumab has recently shown an increase in progression-free survival compared to vorinostat in patients previously treated for cutaneous T-cell lymphoma. Objectives To investigate immune side effects of mogamulizumab in patients with Sezary syndrome. Materials & methods Three patients with Sezary syndrome, treated with mogamulizumab, who developed clinically confirmed vitiligo, were investigated. Results Case 1 was a 66-year-old woman from Tunisia. Seven months after the administration of mogamulizumab, she developed vitiligo on her face and hands while still in complete remission for Sezary syndrome. Case 2 was a 72-year-old woman from Martinique, with no history of autoimmune disease, who was diagnosed with Stage IVA1 Sezary syndrome. The patient received multiple lines of treatment with no improvement. After six months of mogamulizumab treatment, while still on treatment, the patient progressively developed well-demarcated depigmented patches on the scalp, upper limbs, and trunk, consistent with vitiligo. Case 3 was a 38-year-old woman from France, who was diagnosed with Sezary syndrome in October 2019. Mogamulizumab therapy was started in December 2019. Eight months later, she developed histologically-confirmed vitiligo on her legs. Conclusion Vitiligo can be another autoimmune manifestation associated with mogamulizumab, and the occurrence of vitiligo could be a favourable predictive factor for response to treatment.

Mogamulizumab, an anti-CCR4 monoclonal antibody, has been shown to increase progression-free survival in cutaneous T-cell lymphoma.We hypothesized that besides the targeted depletion of Sézary cells (SCs), mogamulizumab may reshape the immune tumour microenvironment.Both malignant and benign compartments from 26 patients with B2 stage Sézary syndrome before mogamulizumab initiation were prospectively analysed using KIR3DL2 and TCRVβ markers, serological markers and molecular assessments of clonality.Prior to mogamulizumab, the benign subset of CD4Mogamulizumab likely contributes to the restoration of efficient immunity and reshapes not only the malignant lymphocyte subset but also the benign subset. These results have potential implications for optimal therapeutic sequences and/or combinations. What is already known about this topic? Management of Sézary syndrome (SS) involves successive therapies that participate as cause and consequence in the emergence of resistant clones, on a background of immunodeficiency. We and others have reported the complex and dynamic heterogeneity of Sézary cells (SCs) during disease progression. Mogamulizumab therapy, by targeting the skin-homing receptor CCR4, mainly expressed by SCs, has been shown to increase progression-free survival in patients with SS. What does this study add? Using multicolour flow cytometry, we provide quantification of CCR4 and immune checkpoint molecules on malignant SCs and benign CD4

Applying next-generation sequencing to paired skin and marrow biopsies, Delaleu et al describe an entity they term “myelodysplasia cutis,” comprising histologic features of histiocytoid Sweet syndrome in the skin and a clonally related myelodysplasia in the bone marrow. This can be distinguished from forms of histiocytoid Sweet syndrome not associated with myelodysplastic syndromes, as well as classical neutrophilic Sweet syndrome associated with various malignant and nonmalignant diseases and leukemia cutis where the infiltrating cells are myeloblasts.

Cutaneous T-cell lymphomas (CTCLs) are rare malignancies involving primarily the skin. Responses to treatment are usually short-lived in advanced CTCL. The determinants of long-term CTCL control are unclear. Mogamulizumab, an anti-human CCR4 antibody that acts by antibody-dependent cell cytotoxicity against CCR4+ CTCL tumor cells and peripheral memory blood regulatory T cells, has been associated with long-lasting remissions and immune adverse events. Here, we reported skin rashes in 32% of 44 patients with CTCL treated with mogamulizumab, associated with significantly higher overall survival (hazard ratio, 0.16; 0.04-0.73; P = .01). Rash occurred in patients with Sézary syndrome and was associated with longer time to progression. These rashes were characterized by a CD163+ granulomatous and/or CD8+ lichenoid skin infiltrate. High-throughput sequencing analysis of T-cell receptor β genes in skin and blood flow cytometry confirmed the depletion of CTCL tumor cells, as well as the recruitment of new reactive T-cell clones in skin at the time of skin rash. CXCL9 and CXCL11, two macrophage-derived chemokines that recruit CXCR3+ T cells to skin, were overexpressed in skin rashes. A higher frequency of TIGIT+ and PD1+ exhausted reactive blood T cells was observed at baseline in patients with rash, and this frequency decreased with mogamulizumab treatment. These data are consistent with mogamulizumab-induced long-term immune CTCL control by activation of the macrophage and T-cell responses in patients with rash.

Summary Background IPH4102 is a first-in-class monoclonal antibody targeting KIR3DL2, a cell surface protein that is expressed in cutaneous T-cell lymphoma, and predominantly in its leukaemic form, Sezary syndrome. We aimed to assess the safety and activity of IPH4102 in cutaneous T-cell lymphoma. Methods We did an international, first-in-human, open-label, phase 1 clinical trial with dose-escalation and cohort-expansion parts in five academic hospitals in the USA, France, the UK, and the Netherlands. Eligible patients had histologically confirmed relapsed or refractory primary cutaneous T-cell lymphoma, an Eastern Cooperative Oncology group performance score of 2 or less, were aged 18 years or older, and had received at least two previous systemic therapies. Ten dose levels of IPH4102, administered as an intravenous infusion, ranging from 0·0001 mg/kg to 10 mg/kg, were assessed using an accelerated 3 + 3 design. The primary endpoint was the occurrence of dose-limiting toxicities during the first 2 weeks of treatment, defined as toxicity grade 3 or worse lasting for 8 or more days, except for lymphopenia. Global overall response by cutaneous T-cell lymphoma subtype was a secondary endpoint. Safety and activity analyses were done in the per-protocol population. The study is ongoing and recruitment is complete. This trial is registered with ClinicalTrials.gov , number NCT02593045 . Findings Between Nov 4, 2015, and Nov 20, 2017, 44 patients were enrolled. 35 (80%) patients had Sezary syndrome, eight (18%) had mycosis fungoides, and one (2%) had primary cutaneous T-cell lymphoma, not otherwise specified. In the dose-escalation part, no dose limiting toxicity was reported and the trial's safety committee recommended a flat dose of 750 mg for the cohort-expansion, corresponding to the maximum administered dose. The most common adverse events were peripheral oedema (12 [27%] of 44 patients) and fatigue (nine [20%]), all of which were grade 1–2. Lymphopenia was the most common grade 3 or worse adverse event (three [7%]). One patient developed possibly treatment-related fulminant hepatitis 6 weeks after IPH4102 discontinuation and subsequently died. However, the patient had evidence of human herpes virus-6B infection. Median follow-up was 14·1 months (IQR 11·3–20·5). A confirmed global overall response was achieved in 16 (36·4% [95% CI 23·8–51·1]) of 44 patients, and of those, 15 responses were observed in 35 patients with Sezary syndrome (43% [28·0–59·1]). Interpretation IPH4102 is safe and shows encouraging clinical activity in patients with relapsed or refractory cutaneous T-cell lymphoma, particularly those with Sezary syndrome. If confirmed in future trials, IPH4102 could become a novel treatment option for these patients. A multi-cohort, phase 2 trial (TELLOMAK) is underway to confirm the activity in patients with Sezary syndrome and explore the role of IPH4102 in other subtypes of T-cell lymphomas that express KIR3DL2. Funding Innate Pharma

The erythrodermic ulcerated form of mycosis fungoides (MF) is exceptional, and treatment of refractory cases is challenging. Brentuximab vedotin (BV) is a monoclonal antibody combined with monomethyl auristatin E, recently approved for the treatment of refractory CD30+ cutaneous T-cell lymphoma. We report a case of refractory MF in a 56-year-old man with a long history of large-plaque parapsoriasis, as revealed by psoriasiform erythroderma, treated initially with cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) polychemotherapy, inducing a 2-year complete response. After relapse, interferon and gemcitabine were unsuccessful. Finally, treatment with BV was decided upon, despite the absence of CD30 expression. After three infusions of BV 1·8 mg kg-1 , we achieved a complete and stable response, allowing an allogeneic stem cell transplant. The patient is still in complete remission, 19 months after the graft. This case illustrates the possibility of using BV in refractory CD30- MF as a salvage therapy.

The prognosis of erythrodermic cutaneous T-cell lymphomas (ECTL) depends upon lymph node (N), visceral (M) involvement, and blood stage (B, i.e circulating Sezary cells, identified upon peripheral blood immunophenotyping, B0: absolute count 60 years, an elevated rate of lactate dehydrogenase (LDH), and histologic large-cell transformation (LCT).1-3 ECTL progression is usually homogeneous and simultaneously involves all compartments of the disease. We report nine patients with B1 or B2 ECTL displaying an unusually discrepant outcome profile with the rapid onset of N or M involvement contrasting with the lack of progression of cutaneous and blood involvement.

BACKGROUND Lymphomatoid papulosis (LyP) type D (LyP D) and type E (LyP E) have recently been described in small series of cases or isolated case reports. AIM To further describe the clinical and histological features of LyP D and E based on a retrospective multicentre study. METHODS The clinical and histopathological features of 29 patients with an initial diagnosis of LyP D or LyP E were retrospectively assessed using standardized forms. RESULTS After exclusion of 5 cases, 24 patients (14 LyP D, 10 LyP E) were enrolled in the study. The median follow-up was 2.5 years (range 1 month to 13 years). LyP D was characterized by multiple recurrent self-regressing small papules that developed central erosion or necrosis, whereas LyP E presented as papulonodular lesions that rapidly evolved into necrotic eschar-like lesions > 10 mm in size. Epidermal changes were more frequent in LyP D, whereas dermal infiltrates were deeper in LyP E. Anaplastic cytology was rare and the DUSP22 rearrangement was never observed. Two patients (8%) had an associated cutaneous lymphoma. CONCLUSION LyP D and E have distinct clinical findings and may be associated with other cutaneous lymphomas.

Background The PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) study is a prospective analysis of an international database. Here we examine front-line treatments and quality of life (QoL) in patients with newly diagnosed mycosis fungoides (MF).Objectives To identify (i) differences in first-line approaches according to tumour-nodes-metastasis-blood (TNMB) staging; (ii) parameters related to a first-line systemic approach and (iii) response rates and QoL measures.Methods In total, 395 newly diagnosed patients with early-stage MF (stage IA-IIA) were recruited from 41 centres in 17 countries between 1 January 2015 and 31 December 2018 following central clinicopathological review.Results The most common first-line therapy was skin-directed therapy (SDT) (322 cases, 81 center dot 5%), while a smaller percentage (44 cases, 11 center dot 1%) received systemic therapy. Expectant observation was used in 7 center dot 3%. In univariate analysis, the use of systemic therapy was significantly associated with higher clinical stage (IA, 6%; IB, 14%; IIA, 20%; IA-IB vs. IIA, P < 0 center dot 001), presence of plaques (T1a/T2a, 5%; T1b/T2b, 17%; P < 0 center dot 001), higher modified Severity Weighted Assessment Tool (> 10, 15%

Background: The prognosis of Sezary syndrome (SS) and mycosis fungoides (MF) depends on lymph node (LN) involvement. The usefulness of LN image-guided core-needle biopsies (CNBs), instead of surgical sampling, has been poorly evaluated. Objectives: To determine the prognostic value of LN CNB in MF/SS. Methods: A retrospective search was conducted to identify all LN biopsy specimens of MF/SS between 2008 and 2019. Biopsies were staged according to the International Society for Cutaneous Lymphomas/European Organisation for Research and Treatment of Cancer (ISCL/EORTC) criteria. We performed immunolabelling and determined the tumour clone frequency (TCF) by high-throughput sequencing of the T-cell receptor beta locus. Results: We included 119 consecutive biopsies from 100 patients, 45 with MF and 55 with SS. N1, N2 and N3 stages were diagnosed in 34 (29%), 26 (22%) and 59 (49%) cases, respectively. The TCF, Ki67 index, and percentage of cells positive for thymocyte selection-associated high mobility group box protein (TOX), programmed cell death protein 1 (PD1), killer cell immunoglobulin-like receptor 3DL2 (KIR3DL2) and cluster of differentiation (CD)30 were all positively correlated with the N stage. Median overall survival (OS) for N1/N2 vs. N3 patients was 42 months (range 26–not reached) vs. 14 months (range 5–30), respectively (p 75 years, LN short-axis diameter >15 mm, N3 stage, presence of large-cell transformation, TOX >60%, PD1 >25%, Ki67 >30%, KIR3DL2 >15%, CD30 >10% and TCF >25% were identified as adverse prognostic factors. In multivariate analyses, only an age >75 years and Ki67 index >30% were associated with reduced OS. We developed a new prognostic index associating the N stage and the Ki67 index, which better discriminates N3 patients with poor prognosis. Conclusions: CNB allows an objective assessment of the LN involvement in MF/SS, relevant for staging and prognosis.

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of rare diseases. Many studies have reported on local epidemiology or geographic clustering, however we lack information from a global perspective. A systematic review and meta-analysis was conducted in Medline and the Cochrane Library based on a previously registered protocol and according to the preferred reporting of items for systematic reviews and meta-analyses (PRISMA). We selected publications that enrolled at least 100 patients with primary cutaneous lymphomas according to the current classifications. The relative frequencies (proportions) of subtypes were compared between studies and geographic regions in a meta-analysis. In total, 26 studies met our inclusion criteria, reporting on altogether 16,953 patients. Within primary cutaneous lymphomas, CTCL appeared to be 15% more frequent in Asian populations. Mycosis fungoides (MF) accounted for 62% of CTCL, with an important heterogeneity in frequencies between studies and continents. The proportion of S&eacute, zary syndrome (SS) was 3%, stable worldwide. Rare CTCL, such as NK/T-cell lymphoma or subcutaneous panniculitis-like lymphoma, were more frequent in Asian studies. This global meta-analysis of CTCL confirmed the predominance of CTCL among primary cutaneous lymphomas (83% on average) in the three analyzed continents, most of which were MF cases. It revealed the same proportions of SS across continents, and the heterogeneity of MF frequencies, suggesting the possible role of environmental factors in the pathophysiology of the latter. Registration number: CRD42020148295 (PROSPERO).

Simple Summary Advanced-stage cutaneous T-cell lymphomas are aggressive diseases with frequent disease relapses and a reduced overall survival. Most treatment regimens fail to induce long-term remissions. Allogeneic hematopoietic stem cell transplantation has been associated with treatment-free long-term remissions and holds a potential for cure in this disease but is associated with frequent complications, mostly linked to the development of graft-versus-host disease and infections. Herein, we review the current evidence supporting the use of allogeneic stem cell transplantation in advanced-stage cutaneous T-cell lymphomas. Abstract Cutaneous T-cell lymphomas (CTCLs) are non-Hodgkin lymphomas that develop primarily in the skin. They account for almost 80% of primary cutaneous lymphomas. Epidermotropic CTCLs (mycosis fungoides (MF) and Sézary syndrome (SS)) are the most common form of CTCL. The course of the disease ranges from an indolent clinical behavior in early-stage disease to an aggressive evolution in the advanced stages. Advanced-stage disease is defined by the presence of tumors, erythroderma, or significant blood, nodal or visceral involvement. Advanced-stage disease is characterized by frequent disease relapses, refractory disease, a severely impaired quality of life and reduced overall survival. In the last twenty-five years, allogeneic hematopoietic stem cell transplantation (HSCT) has led to prolonged remissions in advanced CTCL, presumably linked to a graft-versus-lymphoma effect and is thus emerging as a potential cure of the disease. However, the high post-transplant relapse rate and severe morbidity and mortality associated with graft-versus-host disease and infections are important issues. Allogeneic HSCT is thus mostly considered in young patients with no comorbidities and an aggressive, advanced-stage CTCL. Allogeneic HSCT gives the best results in patients with a pre-transplant complete remission of the lymphoma. For this reason, one of the challenges is to define the best time to consider allogeneic HSCT in the disease course. Early identification of patients at high risk for progression is important to identify candidates who may benefit from allogeneic HSCT before their disease becomes treatment-refractory. This review describes the role of allogeneic HSCT in CTCL, summarizes the published data and future perspectives in this area.

is missing (Short communication)

Myelodysplastic syndromes (MDS) are malignant hematopoietic stem cell disorders characterized by dysplastic and ineffective blood cell production leading to blood cytopenias, and a risk of transformation to acute myeloid leukemia (AML). Skin lesions in patients with MDS include Sweet syndrome (SS), leucocytoclastic vasculitis, leukemia cutis and histiocytoid SS (H-SS), among others,.1,2 H-SS is a histological variant of SS differing from classical neutrophilic SS by a dermal infiltrate mostly made of immature cells of the myeloid lineage, that has been associated with myeloid malignancies.

is missing (Short communication)

International audience; Skin involvement in Waldenström's macroglobulinaemia is poorly described, and diagnosis of this disorder may be difficult. Many differential diagnoses are possible (other lymphomas, primary cutaneous lymphoma, etc.). Describing 2 aspects of Waldenström's macroglobulinaemia (infiltration by lymphoplasmacytic tumour cells or histological transformation into diffuse large B-cell lymphoma) allows the identification of clinical, histological and immunohistochemical diagnostic aids. Detection of the MYD88 L265P mutation is of interest. This study identified a characteristic clinical picture in non-transformed cases, and was able to distinguish between transformed and non-transformed cases by their severity and poor prognosis. Cutaneous involvement in Waldenström's macroglobulinaemia (WM) has been poorly characterized. To describe this involvement, a retrospective study of 19 patients with WM and cutaneous involvement of tumour B cells was performed. Twelve patients (group 1) had lymphoplasmacytic, non-transformed cutaneous proliferation, while in 7 cases (group 2) cutaneous involvement corresponded to histological transformation. In group 1, skin involvement was inaugural in 6 cases. The lesions were infiltrated plaques (83%), papules (25%) and tumours (42%). Four patients had a similar clinical picture (purplish, bilateral and symmetrical infiltration on the face). MYD88 L265P mutation was detected in the skin biopsy in all 6 cases tested. The 3-year specific survival rate was 88%. In group 2, cutaneous transformation occurred during the followup of the WM (71%). Lesions presented as ulcerated tumours (86%) of the trunk (57%) and lower limbs (57%). The 3-year specific survival rate was 22%. Skin involvement in WM has distinctive characteristics (e.g. clinical, histological, immunohistochemical, MYD88 L265P mutation).

Primary cutaneous B-cell lymphomas are rare entities that develop primarily in the skin. They constitute a heterogeneous group that represents around a quarter of primary cutaneous lymphomas. The 2018 update of the World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification differentiates primary cutaneous marginal zone lymphoma and primary cutaneous follicle center lymphoma with an indolent course from primary cutaneous diffuse large B-cell lymphoma, leg type with an aggressive behavior. The broad spectrum of clinical presentations and the disease course marked by frequent relapses are diagnostic and therapeutic challenges. The classification of these diseases has been refined in recent years, which allows to better define their immunopathogenesis and specific management. In the present article, we review the main clinico-biological characteristics and the current therapeutic options of these three main subsets. Based on the recent therapeutic advances in nodal B-cell lymphomas, we focus on the development of novel treatment options applicable to primary cutaneous B-cell lymphomas, including targeted therapies, combination treatments and immunotherapeutic approaches, and cover basic, translational and clinical aspects aiming to improve the treatment of cutaneous B-cell lymphomas.

Background Primary cutaneous lymphomas (PCLs) are a heterogeneous group of T-cell (CTCL) and B-cell (CBCL) malignancies. Little is known about their epidemiology at initial presentation in Europe and about potential changes over time. Objectives The aim of this retrospective study was to analyse the frequency of PCLs in the French Cutaneous Lymphoma Registry (GFELC) and to describe the demography of patients. Methods Patients with a centrally validated diagnosis of primary PCL, diagnosed between 2005 and 2019, were included. Results The calculated incidence was unprecedently high at 1·06 per 100 000 person-years. The number of included patients increased yearly. Most PCL subtypes were more frequent in male patients, diagnosed at a median age of 60 years. The relative frequency of rare CTCL remained stable, the proportion of classical mycosis fungoides (MF) decreased, and the frequency of its variants (e.g. folliculotropic MF) increased. Similar patterns were observed for CBCL; for example, the proportion of marginal-zone CBCL increased over time. Conclusions Changes in PCL frequencies may be explained by the emergence of new diagnostic criteria and better description of the entities in the most recent PCL classification. Moreover, we propose that an algorithm should be developed to confirm the diagnosis of PCL by central validation of the cases.

International audience; In nodal diffuse large B-cell lymphoma, the search for double-hit with MYC and BCL2 and/or BCL6 rearrangements or for dual expression of BCL2 and MYC defines subgroups of patients with altered prognosis that has not been evaluated in primary cutaneous large B-cell lymphoma. Our objectives were to assess the double-hit and dual expressor status in a cohort of 44 patients with primary cutaneous large B-cell lymphoma according to the histological subtype and to evaluate their prognosis relevance. The 44 cases defined by the presence of more than 80% of large B-cells in the dermis corresponded to 21 primary cutaneous follicle centre lymphoma with large cell morphology and 23 primary cutaneous diffuse large B-cell lymphoma, leg type. Thirty-one cases (70%) expressed BCL2 and 29 (66%) expressed MYC. Dual expressor profile was observed in 25 cases (57%) of either subtypes (n = 6 or n = 19, respectively). Only one primary cutaneous follicle centre lymphoma, large-cell case had a double-hit status (2%). Specific survival was significantly worse in primary cutaneous diffuse large B-cell lymphoma, leg type than in primary cutaneous follicle centre lymphoma, large cell (p = 0.021) and for the dual expressor primary cutaneous large B-cell lymphoma group (p = 0.030). Both overall survival and specific survival were worse for patients belonging to the dual expressor primary cutaneous diffuse large B-cell lymphoma, leg type subgroup (p = 0.001 and p = 0.046, respectively). Expression of either MYC and/or BCL2 negatively impacted overall survival (p = 0.017 and p = 0.018 respectively). As the differential diagnosis between primary cutaneous follicle centre lymphoma, large cell and primary cutaneous diffuse large B-cell lymphoma, leg type has a major impact on prognosis, dual-expression of BCL2 and MYC may represent a new diagnostic criterion for primary cutaneous diffuse large B-cell lymphoma, leg type subtype and further identifies patients with impaired survival. Finally, the double-hit assessment does not appear clinically relevant in primary cutaneous large B-cell lymphoma.

BACKGROUND Primary cutaneous B-cell lymphomas represent approximately 25% of primary cutaneous lymphomas. Follicular centre cell lymphomas (PCFCL) and marginal zone lymphomas (PCMZL) are the two histological subtypes that present an indolent evolution. Radiotherapy is one of the recommended treatment options with few series reported. OBJECTIVE This study aimed to evaluate radiotherapy outcomes in term of overall survival (OS) and disease-free survival (DFS) for patients suffering from a PCMZL or PCFCL, to search for predictive factors of recurrence, and to evaluate chronic and aesthetics adverse events and patient's satisfaction. METHODS Patients treated with contact low energy radiotherapy for a PMZCL or PCFCL from April 2009 to June 2017 in Saint Louis hospital were retrospectively analysed. Total dose ranged from 18 to 30 Gy. Objective response (OR) rates, DFS and OS as patterns of recurrence according to radiation fields were analysed. Univariate analysis of DFS has been performed according to clinical and biological parameters. Acute toxicity, long-term adverse events and satisfaction were collected via individualized questionnaires. RESULTS Forty-six patients were included. Median follow-up was 43.5 months. OR was achieved for 100% of cases. Recurrence occurred in 39% of cases. Median DFS was 44 months. Three-year DFS and 5-year DFS were 56% and 51%, respectively. OS at 3 and 5 year was 100%. Only sex was significantly associated with DFS. Acute AEs occurred in 48% of cases without grade 3 and 4. 55% reported some moderate aesthetic sequelae for long-term AEs. 97% were satisfied with treatment. CONCLUSION This study confirms the good risk-benefit of radiotherapy for the treatment of primary cutaneous indolent B-cell lymphomas due to the high response rate and a long DFS. No significant factor for recurrence was identified, except female sex. Long-term aesthetic evaluation was good or excellent for most of the patients.