On behalf of the EORTC Cutaneous Lymphoma Tumours Group (EORTC-CLTG) and following up on earlier versions published in 2006 and 2017 this document provides an updated standard for the treatment of mycosis fungoides and Sézary syndrome (MF/SS). It considers recent relevant publications and treatment options introduced into clinical practice after 2017. Consensus was established among the authors through a series of consecutive consultations in writing and a round of discussion. Treatment options are assigned to each disease stage and, whenever possible and clinically useful, separated into first- and second line options annotated with levels of evidence. Major changes to the previous version include the incorporation of chlormethine, brentuximab vedotin, and mogamulizumab, recommendations on the use of pegylated interferon α (after withdrawal of recombinant unpegylated interferons), and the addition of paragraphs on supportive therapy and on the care of older patients. Still, skin-directed therapies are the most appropriate option for early-stage MF and most patients have a normal life expectancy but may suffer morbidity and impaired quality of life. In advanced disease treatment options have expanded recently. Most patients receive multiple consecutive therapies with treatments often having a relatively short duration of response. For those patients prognosis is still poor and only for a highly selected subset long term remission can be achieved with allogeneic stem cell transplantation. Understanding of the disease, its epidemiology and clinical course, and its most appropriate management are gradually advancing, and there is well-founded hope that this will lead to further improvements in the care of patients with MF/SS.

Background: Cutaneous lymphomas expressing CD56, a neural cell adhesion molecule, are characterised in most cases by a highly aggressive clinical course and a poor prognosis. However, prognostic subsets within the CD56+ group have been difficult to identify due to the lack of uniform clinicopathological and immunophenotypical criteria. Methods: A multicentre study was conducted by the Cutaneous Lymphoma Task Force of the European Organisation for Research and Treatment of Cancer to define prognostic parameters and establish diagnostic and therapeutic guidelines for CD56+ haematological neoplasms presenting primarily in the skin. Results: Four different subtypes of lymphoproliferations with CD56 expression were identified: (1) haematodermic neoplasm; (2) skin infiltration as the first manifestation of CD56+ acute myeloid leukaemia; (3) nasal-type extranodal natural killer/T-cell lymphoma; and (4) “classical” cases of cutaneous T-cell lymphoma (CTCL) with co-expression of the CD56 molecule. Patients in the first three groups had a poor outcome (93% died) with a median survival rate of 11 months (95% CI 2–72 months), whereas all patients with CD56+ CTCL were alive at the last follow-up. Conclusion: Results show that CD56+ cutaneous lymphoproliferative disorders, with the exception of CD56+ CTCL have a very poor prognosis. It is therefore clinically important to separate CD56+ CTCL from the remaining CD56+ haematological disorders.

The lymph nodes are generally the first extracutaneous manifestation in patients with cutaneous T-cell lymphoma (CTCL); however, their early involvement is difficult to assess. The aim of our study was to define the diagnostic and prognostic value of T-cell clonality analysis for a more precise assessment of lymph node involvement in CTCL. T-cell clonality was determined by 2 independent polymerase chain reaction (PCR) assays, namely a recently developed T-cell receptor-β (TCR-β) PCR technique as well as an established TCR-γ PCR. T-cell clonality was found in 22 of 22 lymph nodes with histologically detectable CTCL involvement as well as in 7 of 14 histologically noninvolved dermatopathic lymph nodes. The clonal T-cell populations in the lymph nodes were in all cases identical to those detected in the corresponding skin lesions, identifying them as the tumor cell population. T-cell clonality was not found in any of the 12 dermatopathic lymph nodes from 12 patients with inflammatory skin diseases. Clonal T-cell detection in 7 of 14 dermatopathic lymph nodes of patients with CTCL was associated with limited survival (74 months; confidence interval [CI], 66-82 months) as in patients with histologically confirmed lymph node involvement (41 months; CI, 35-47 months), whereas all patients without T-cell clonality in the lymph nodes (7 patients) were alive at the last follow-up. Thus, T-cell clonality analysis is an important adjunct in differentiating benign dermatopathic lymphadenitis from early CTCL involvement.

Cutaneous T-cell lymphomas (CTCLs) are a group of lymphoid neoplasms with high relapse rates and no curative treatment other than allogeneic stem cell transplantation (allo-SCT). CTCL is significantly influenced by disruption of JAK/STAT signaling. Therefore, Janus kinase (JAK) inhibitors may be promising for CTCL treatment. This study is a systematic review aiming to investigate the role of JAK inhibitors in the treatment of CTCL, including their efficacy and safety. Out of 438 initially searched articles, we present 13 eligible ones. The overall response rate (ORR) in the treatment with JAK inhibitors in clinical trials was 11–35%, although different subtypes of CTCL showed different ORRs. Mycosis fungoides showed an ORR of 14–45%, while subcutaneous-panniculitis-like T-cell lymphoma (SPTCL) displayed an ORR ranging from 75% to 100%. Five cases were reported having a relapse/incident of CTCL after using JAK inhibitors; of these, three cases were de novo CTCLs in patients under treatment with a JAK inhibitor due to refractory arthritis, and two cases were relapsed disease after graft-versus-host disease treatment following allo-SCT. In conclusion, using JAK inhibitors for CTCL treatment seems promising with acceptable side effects, especially in patients with SPTCL. Some biomarkers, like pS6, showed an association with better responses. Caution should be taken when treating patients with an underlying autoimmune disease and prior immunosuppression.