The 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas.

Primary cutaneous lymphomas are a heterogeneous group of T- and B-cell lymphomas that present in the skin with no evidence of extracutaneous disease at the time of diagnosis. The 2005 World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) consensus classification has served as a golden standard for the diagnosis and classification of these conditions. In September 2018, an updated version of the WHO-EORTC was published in the fourth edition of the WHO Classification of Skin Tumours Blue Book. In this classification, primary cutaneous acral CD8+ T-cell lymphoma and Epstein-Barr virus positive (EBV+) mucocutaneous ulcer are included as new provisional entities, and a new section on cutaneous forms of chronic active EBV disease has been added. The term "primary cutaneous CD4+ small/medium T-cell lymphoma" was modified to "primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder" because of its indolent clinical behavior and uncertain malignant potential. Modifications have also been made in the sections on lymphomatoid papulosis, increasing the spectrum of histologic and genetic types, and primary cutaneous marginal zone lymphomas recognizing 2 different subtypes. Herein, the characteristic features of these new and modified entities as well as the results of recent molecular studies with diagnostic, prognostic, and/or therapeutic significance for the different types of primary cutaneous lymphomas are reviewed. An update of the frequency and survival of the different types of primary cutaneous lymphomas is provided.

Solitary CD8-Positive Primary Cutaneous Peripheral T-Cell Lymphoma: A Question of Classification.

ABSTRACT: Acral CD8(+) lymphoma is a provisional entity in the latest edition of the WHO Lymphoma Classification and is associated with a highly specific dot-like pattern of immunohistochemical expression of CD68. We report a case of an ulcerated solitary cutaneous lesion arising on the forehead of an adult man, which had a CD8(+) cytotoxic phenotype and areas of dot-like CD68 positivity, but with a number of features that significantly detracted from the classically described acral CD8(+) lymphoma. The nosological status of the lesion is discussed with respect to a preferred diagnosis of peripheral T-cell lymphoma, not otherwise specified.

[Primary cutaneous lymphoma-a case series of 163 patients]. / Primär kutane Lymphome ­ eine Fallserie von 163 Patienten.

BACKGROUND: In addition to a broad and clinically diverse spectrum of known primary cutaneous lymphomas, for which an incidence of 1-3:100,000 is postulated, each year further entities are specified and defined. The goal is the presentation of a case series from daily clinical routine. METHODS: Over a period of 6 years and 2 months, patients consulting the Department of Dermatology, Medical Center University of Freiburg, were registered. Subsequently, collectives of mycosis fungoides (MF), Sezary syndrome (SS), CD30+ lymphoproliferative diseases, single cases with rare primary cutaneous lymphomas, and subcollectives of B­cell lymphomas were examined. The high number of MF cases allowed the additional quantitative analyses of the types of therapies used in this group. RESULTS: Yearly 16-25 new diagnoses of primary cutaneous lymphoma are made. The evaluation of 163 primary cutaneous lymphoma revealed 111 cases with MF (68.1%), including 9 particular variants, 15 primary cutaneous CD30+ lymphoproliferative diseases (9.2%) dominated by 10 lymphomatoid papulosis (LyP), in addition to 5 primary cutaneous anaplastic large cell lymphoma (PCALCL), 6 SS (3.68%), and 24 cutaneous B­cell lymphomas (14-72%). Three cases with rare primary cutaneous T/NK cell lymphomas are addressed in detail. In all, 82% of MF cases were stage IA and IB. The descending use of therapies for stage I-III included steroids and diverse UV therapies followed by bexarotene, interferon-α, methotrexate, and extracorporal photophoresis. CONCLUSIONS: Diagnoses of cutaneous lymphomas belong to a vast spectrum of differential diagnoses. This registry describes frequent findings and shows rare variants. You can only diagnose what you know; accordingly, a collection of case reports, which we wish to encourage, can help in processing and specification of entities.

Clinical manifestations and pathogenesis of cutaneous lymphomas: current status and future directions.

The primary cutaneous lymphomas are a heterogeneous group of T-, Natural Killer- and B- cell neoplasms with a wide range of clinical and pathological presentations, and with very different prognoses compared to systemic lymphomas. Recent studies have shown that the skin microenvironment, which is composed of various immune cell subsets as well as their spatial distribution and T-cell interactions through different chemokines and cytokines, has an important role in the development and pathogenesis of cutaneous lymphomas and has assisted in the development of novel and more effective immunotherapies. The following review will focus on the major subtypes of primary cutaneous lymphomas, including the clinical and histological patterns, molecular hallmarks, and current and future treatment strategies.

Cutaneous intravascular natural killer/T cell lymphoma with peculiar immunophenotype.

Intravascular lymphoma (IVL) is a rare entity. Most cases are a variant of extranodal diffuse large B cell lymphoma, and fewer than 10% of the published cases are of T cell origin. Only intravascular B cell lymphoma is recognized as a distinct entity in the most recent World Health Organization (WHO) classification of lymphoproliferative disorders. We describe a case of cutaneous natural killer (NK)/T IVL, with a cytotoxic immunophenotype and Epstein-Barr virus (EBV) positivity. However, our case was immunohistochemically negative not only for T cell receptor (TCR)-ßF1 and TCR-γ (TCR-silent), but also for CD56, making it the first triple-negative NK/T IVL case to be described. We urge recognition of this NK/T cell lineage intravascular lymphoma due to its particular immunophenotypical profile and its unvarying relationship with EBV. Its occurrence should not be considered a coincidence, but rather a key aspect of the pathogenic background of this haematological neoplasm.

[WHO classification and clinical spectrum of cutaneous lymphomas]. / WHO-Klassifikation und klinisches Spektrum der kutanen Lymphome.

BACKGROUND: Cutaneous lymphomas are rare skin cancers with a wide clinical spectrum. OBJECTIVE: To give an overview of the current classification and the clinical spectrum of cutaneous lymphomas. MATERIAL AND METHODS: Analysis and summary of the current literature concerning the different entities of cutaneous lymphomas. RESULTS: A few modifications in the nomenclature of cutaneous lymphoma have been introduced in the revised version of the WHO classification 2016. In the last years new types of lymphomatoid papulosis were described. Moreover, two subgroups of folliculotropic mycosis fungoides are now mentioned. The CD4+ small/medium T­cell lymphoproliferative disorder is no longer classified as an overt lymphoma. As new entities the EBV+ mucocutaneous ulcer, an EBV-associated diffuse large B­cell lymphoma (not otherwise specified) and a primary cutaneous acral CD8+ T­cell (provisional) lymphoma are being considered. CONCLUSION: The classification of cutaneous lymphomas is based on the revised version of the WHO classification (2016). The clinical pathological correlation is an elementary component for correct diagnosis.

[Treatment of rare cutaneous T­cell lymphoma and blastic plasmacytoid dendritic cell neoplasm]. / Therapie seltener kutaner T­Zell-Lymphome und der blastären plasmazytoiden dendritischen Zellneoplasie.

Among the group of primary cutaneous lymphomas several subtypes have very low incidence rates. Based on the revision of the WHO classification for lymphoid neoplasms (2016), an overview of rare cutaneous T­cell lymphoma (CTCL) subtypes is given and therapeutic approaches are detailed. The prognosis of the different subtypes is highly variable underlining the importance of adequate stage and subtype adapted treatment. In cases of indolent subtypes topical treatment, e. g. topical corticosteroids or UV phototherapy are often sufficient. For aggressive variants, early discussion of more aggressive systemic treatment options is warranted.

FoxP3-positive T cell lymphoma arising in non-HTLV1 carrier: clinicopathological analysis of 11 cases of PTCL-NOS and 2 cases of mycosis fungoides.

AIMS: Forkhead box protein 3-positive (FoxP3(+) ) T cell lymphoma, in the absence of human T cell lymphotrophic virus type 1 (HTLV-1) infection, is rare and its clinicopathological characteristics still remain unclear. The aim of this study was to elucidate its characteristics. METHODS AND RESULTS: We describe here 11 cases of peripheral T cell lymphoma not otherwise specified (PTCL-NOS) and two cases of mycosis fingoides (MF) which were positive for FoxP3. The median age of the 11 PTCL-NOS cases was 65 years (range: 48-80 years), and all the patients were male. Eight patients (80%) showed stages III/IV disease, and six (60%) were categorized as high-intermediate/high-risk groups according to the International Prognostic Index. Two cases of MF were 57- and 59-year-old males. Both cases were categorized as stage IA, according to International Society for Cutaneous Lymphomas/European Organization of Research and Treatment of Cancer (ISCL/EORTC) classification. Immunohistochemically, all the cases were negative for cytotoxic molecule marker, and nine (75%) were αß T cell type. Scattered Epstein-Barr virus (EBV)-infected cells were detected in four cases of PTCL-NOS, implying the reactivation of EBV caused by the immunodeficient status of the patients. CONCLUSIONS: FoxP3(+) PTCL-NOS constitute a minor phenotypical subtype with poor prognosis and EBV reactivation in some. Conversely, two cases of MF showed an indolent clinical course which was different from previously reported cutaneous T cell lymphoma (CTCL) cases.

Aggressive epidermotropic cutaneous CD8+ lymphoma: a cutaneous lymphoma with distinct clinical and pathological features. Report of an EORTC Cutaneous Lymphoma Task Force Workshop.

AIMS: Aggressive epidermotropic cutaneous CD8(+) lymphoma is currently afforded provisional status in the WHO classification of lymphomas. An EORTC Workshop was convened to describe in detail the features of this putative neoplasm and evaluate its nosological status with respect to other cutaneous CD8(+) lymphomas. METHODS AND RESULTS: Sixty-one CD8(+) cases were analysed at the workshop; clinical details, often with photographs, histological sections, immunohistochemical results, treatment and patient outcome were discussed and recorded. Eighteen cases had distinct features and conformed to the diagnosis of aggressive epidermotropic cutaneous CD8(+) lymphoma. The patients typically present with widespread plaques and tumours, often ulcerated and haemorrhagic, and histologically have striking pagetoid epidermotrophism. A CD8(+) /CD45RA(+) /CD45RO(-) /CD2(-) /CD5(-) /CD56(-) phenotype, with one or more cytotoxic markers, was found in seven of 18 patients, with a very similar phenotype in the remainder. The tumours seldom involve lymph nodes, but mucosal and central nervous system involvement are not uncommon. The prognosis is poor, with a median survival of 12 months. Examples of CD8(+) mycosis fungoides, lymphomatoid papulosis and Woringer-Kolopp disease presented the typical features well documented in the CD4(+) forms of those diseases. CONCLUSIONS: Aggressive epidermotropic cutaneous CD8(+) lymphoma is a distinct lymphoma that warrants inclusion as a distinct entity in future revisions of lymphoma classifications.

Hydroa vacciniforme-like lymphoma with primarily periorbital swelling: 7 cases of an atypical clinical manifestation of this rare cutaneous T-cell lymphoma.

Hydroa vacciniforme-like lymphoma (HVL) is a rare cutaneous T-cell lymphoma that is usually seen in children of Hispanic or Asian origin. Association between chronic latent Epstein-Barr virus infection in both hydroa vacciniforme (HV) and HVL has been demonstrated and has recently been categorized by the World Health Organization as one of the Epstein Barr virus-positive lymphoproliferative disorders of childhood. Patients with HVL present with a cutaneous rash characterized by edema, blisters, ulcers, and scars mainly seen on the face and extremities that mimic HV; however, unlike in HV, the lesions tend to be extensive and deeper and are associated with severe scarring, necrosis, and systemic manifestations. We are reporting 7 cases of an unusual clinical variant of HVL with primarily periorbital edema. All of our patients in this series presented with progressive periorbital edema that was accompanied with systemic symptoms including fever, malaise, and lymphadenopathy. Most cases were initially misinterpreted as inflammatory processes including cellulitis, arthropod bite reactions, and periorbital lupus erythematosus. The biopsy of these lesions revealed an atypical lymphocytic infiltrate predominantly distributed in the deep dermis and in subcutaneous fat. Immunohistochemistry studies revealed a cytotoxic T-cell (CD8) profile. All cases were associated with Epstein-Barr virus infection. Our study presents a rare clinical variant of HVL with predominant periorbital edema. This variant could potentially be overlooked and misdiagnosed as an inflammatory condition; thus, it needs to be included in the differential diagnosis of periorbital edema in young patients.

Frequency of primary cutaneous lymphoma variants in Austria: retrospective data from a dermatology referral centre between 2006 and 2013.

BACKGROUND: Primary cutaneous lymphomas (PCL) are a heterogenous group of rare lymphoid neoplasms with incomplete information on global and regional prevalence. The recently introduced lymphoma classifications define distinctive clinicopathological disease entities that should allow for more accurate epidemiological assessment. OBJECTIVE: The aim of this study was to evaluate the prevalence and clinical spectrum of PCL diagnosed and treated at the Department of Dermatology and Venereology in St. Pölten, Lower Austria, a dermatology referral centre providing secondary and tertiary care for a population of about 600 000. METHODS: In this retrospective study pathology reports, electronically archived between 2006 and 2013, were screened for the terms lymphoma, mycosis fungoides (MF) and lymphomatoid papulosis (LyP). Patients were diagnosed according to the current WHO-EORTC classification for cutaneous lymphomas and results were compared with data from European, US and Asian centres. RESULTS: Among 86 patients with PCL (age 58.3 ± 17.35 years, mean ± SD; women 38%, n = 33; men 62%, n = 53) 83% (n = 71) were classified as cutaneous T-cell lymphomas (CTCL) and 17% (n = 15) as cutaneous B-cell lymphomas (CBCL). Nine patients with CTCL showed associated haematological disorders and malignomas. Among 47 MF patients following variants were observed: pilotropic MF (n = 2), follicular mucinosis (n = 1), unilesional MF (n = 1), large-cell transformation (n = 3), erythrodermic MF (n = 1), poikilodermatous MF (n = 2) and posttransplant lymphoproliferative disorder (CD8(+) MF with gamma/delta phenotype after renal transplantation) (n = 1). One patient had MF concurrent with lymphomatoid papulosis. The group of CBCL comprised six cases (40%) of PCMZL and PCFCL each, 20% (n = 3) were classified as PCLBCL, LT. CONCLUSION: This study for the first time provides data on the distribution of PCL clinicopathologic variants and stages according to the latest classification and staging systems in an Austrian referral centre.

[Cutaneous lymphomas: new entities and rare variants]. / Kutane Lymphome: Neue Entitäten und seltene Varianten.

Primary cutaneous lymphomas are the second most common group of extranodal non-Hodgkin lymphomas. Recently several new variants and entities have been described but have not yet become part of the World Health Organization (WHO) classification. These forms include the granulomatous form of mycosis fungoides, which is associated with a poorer prognosis, as well as indolent CD8+ lymphoproliferations on the head and at acral localizations. Within the group of cutaneous CD30+ lymphoproliferative disorders, new histological types of lymphomatoid papulosis have been identified, such as type D (CD8+ epidermotropic) and type E (angioinvasive) which simulate aggressive lymphomas. Cutaneous peripheral T-cell lymphomas are a prognostically heterogeneous group of cutaneous lymphomas. The cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma and cutaneous gamma/delta T-cell lymphoma are very aggressive neoplasms, whereas cutaneous CD4+ small to medium-sized T-cell lymphoma in its solitary or localized form represents an indolent lymphoproliferation: the terminology, histogenesis and differentiation from nodular T-cell pseudolymphoma are still a matter of debate. Among B-cell lymphomas, disorders associated with Epstein-Barr virus (EBV) are discussed focusing on EBV diffuse large B-cell lymphoma of the elderly and EBV-associated mucocutaneous ulcer. This review describes the clinical, histological and immunophenotypic features of new and rare entities and variants of cutaneous lymphomas and highlights the impact of the clinicopathological correlation in the diagnostic process.

Cutaneous EBV-positive γδ T-cell lymphoma vs. extranodal NK/T-cell lymphoma: a case report and literature review.

Primary cutaneous γδ T-cell lymphoma and extranodal natural killer (NK)/T-cell lymphoma (ENKTL), nasal type are two distinct lymphoma entities in the World Health Organization (WHO) classification. We report the case of an aggressive cutaneous lymphoma of γδ T-cell origin showing overlapping features of both lymphomas. A 78-year-old female presented with confluent erythematous plaques with ulcerations over her right thigh. Microscopically, section of the skin showed a diffuse dermal and subcutaneous lymphocytic infiltration with tumor necrosis and angioinvasion. The medium- to large-sized tumor cells expressed CD3, CD8, cytotoxic molecules and T-cell receptor (TCR)-γ but not CD4, CD20, CD30, CD56 or ßF1. In situ hybridization for Epstein-Barr virus-encoded mRNA (EBER) was diffusely positive. Polymerase chain reaction-based clonality assay showed a clonal TCR-γ chain gene rearrangement. The features compatible with γδ T-cell lymphoma include dermal and subcutaneous involvements, cytotoxic phenotype, expression of TCR-γ, as well as an aggressive course. On the other hand, the diffuse EBER positivity, angioinvasion, tumor necrosis and cytotoxic phenotype may also fit in the diagnosis of an ENKTL of T-cell lineage. We review the literature on EBER-positive γδ T-cell lymphoma and discuss the diagnostic dilemma using the current WHO classification system.

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(FH)CL) 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(FH)CL (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(FH)CL clinicopathologically is prone to be mistaken for CFCL. Importantly, CT(FH)CL might lose PD-1 while retaining CD10 expression in later stages, which may lead to confusion in distinguishing CT(FH)CL from CFCL.

Canine inflamed nonepitheliotropic cutaneous T-cell lymphoma: a diagnostic conundrum.

BACKGROUND: Cutaneous T-cell lymphoma (CTCL) in dogs is a heterogeneous disease complex, which consists of nonepitheliotropic (NE) and epitheliotropic forms. These lymphomas are readily recognized by the presence of dominant populations of cytologically atypical lymphocytes. OBJECTIVE: The objective of this study was to introduce the key features of inflamed NE-CTCL, which is easily confused with reactive, inflammatory histiocytic disease. ANIMALS: Twenty-four dogs (mean age 7.5 years) presented with inflamed NE-CTCL. Lesions presented as nodules, plaques or masses. An initial diagnosis of cutaneous reactive histiocytosis (11 dogs) or histiocytic neoplasia (three dogs) was made by primary pathologists. METHODS: Lesions were assessed by histology and immunohistochemistry to detect canine leukocyte antigens. Lesional genomic DNA was extracted and gene rearrangement analysis of the T-cell receptor γ locus was assessed. RESULTS: The cutaneous lesions consisted of pleocellular infiltration of the dermis with variable extension into the subcutis. The lesions often surrounded vessels and adnexae. Epitheliotropism was minimal or lacking. Small lymphocytes, plasma cells and intermediate to large, cytologically atypical lymphocytes were scattered between prominent histiocytic infiltrates. Atypical lymphocytes often had marked variation in the intensity of CD3 expression. Molecular clonality analysis of the T-cell receptor γ locus revealed clonal expansion of T cells in 22 of 23 dogs tested. CONCLUSION: The recognition of inflamed NE-CTCL and its differentiation from cutaneous reactive histiocytosis depends on careful assessment of lymphocyte morphology and immunostaining patterns. Confirmation of the diagnosis is best accomplished by T-cell antigen receptor gene rearrangement analysis.

Is bone marrow biopsy always indicated in patients with primary cutaneous marginal zone B-cell lymphoma?

Bone marrow involvement at the time of diagnosis is uncommon in patients with primary cutaneous marginal zone B-cell lymphoma (PCMZL). Moreover, in these patients such involvement is rarely found in isolation on diagnosis. Typically the few patients with PCMZL who have early bone marrow involvement also present secondary nodal or visceral involvement, which is detected by other staging studies (usually computed tomography). In recent years, this has given rise to some debate about whether a bone marrow biopsy should be routinely performed in patients diagnosed with PCMZL in view of the good prognosis and low incidence of bone marrow infiltration and/or extracutaneous involvement in this type of lymphoma.

Cutaneous lymphomas in European pet rabbits (Oryctolagus cuniculus).

Cutaneous lymphoma is a common skin neoplasm of pet rabbits in Europe but is rarely reported in pet rabbits in North America. These neoplasms have not been previously characterized, nor has the cause for the apparent predilection for cutaneous lymphoma in European pet rabbits compared with North American pet rabbits been investigated. In this retrospective study, the authors morphologically and immunohistochemically characterized 25 cutaneous lymphomas in European pet rabbits according to the World Health Organization classification. Tumors were classified as diffuse large B cell lymphomas, with 14 lymphomas exhibiting a centroblastic/centrocytic subtype and 11 tumors exhibiting a T cell-rich B cell subtype. To investigate a potential viral etiology of these lymphomas, 3 diffuse large B cell and 3 T cell-rich B cell lymphomas were evaluated by polymerase chain reaction for retroviral and herpesviral genes. Neither virus was detected. In contrast to other domestic animals, cutaneous lymphomas in European pet rabbits were highly pleomorphic and frequently contained multinucleated giant cells. Unexpectedly, the second most common subtype was T cell-rich B cell lymphoma, a subtype that is rare in species other than horses. Based on a limited number of samples, there was no support for a viral etiology that would explain the higher incidence of lymphoma in European pet rabbits compared with American pet rabbits. Further investigation into genetic and extrinsic factors associated with the development of these tumors is warranted.

Comments on cutaneous lymphomas: since the WHO-2008 classification to present.

The last classification of lymphomas of the World Health Organization in 2008 made a few changes from the preceding classification. Although useful, at the same time, it has posed new questions, concerns, and dilemmas which have been raised in the literature. The current report highlights some of these controversies, of each of these primary cutaneous entities, going through cutaneous mature T-cell and NK-cell neoplasms, mature B-cell neoplasms, precursor neoplasms, and other entities, which for several reasons do not fit in the previous categories. It also reviews some advances on many of these lymphomas published in the last 2 years.

Cutaneous peripheral T-cell lymphomas, unspecified/NOS and rare subtypes: a heterogeneous group of challenging cutaneous lymphomas.

Cutaneous peripheral T-cell lymphoma, unspecified/not otherwise specified (PTL NOS) represents a phenotypically and prognostically heterogenous group of cutaneous T-cell lymphomas (CTCL) that do not fit into any of well defined defined CTCL subtypes. In the WHO-EORTC classification as well as the WHO classification, three entities have been delineated as provisional rare subtypes of PTL based on their characteristic clinico-pathological, immunophenotypic and prognostic features and have been separated out from PTL, NOS: Primary cutaneous CD4-positive small/medium T-cell lymphoma (CD4+ SMTL), primary cutaneous CD8-positive aggressive epidermotropic T-cell lymphoma (CD8+ AECTCL), and primary cutaneous gamma/delta T-cell lymphoma (CGD-TCL). CD4+ SMTL manifests in most patients with a solitary nodule in the head and neck area and nodular infiltrates of CD4+ small to medium-sized lymphocytes with nuclear pleomorphism. The prognosis of this lymphoproliferation is excellent in patients with a solitary lesion, but may be impaired in patients with multifocal disease. Rapidly evolving erosive or necrotic plaques and nodules with an epidermotropic infiltrate of CD8+ atypical lymphocytes are the hallmark of CD8+ AECTCL, which exhibits a poor prognosis. CGD-TCL displays a broad spectrum of clinical and histological manifestations with expression of the T-cell receptor gamma/delta chain as the common denominator and diagnostic marker. As most of other forms of PTL, CGD-TCL carries a poor prognosis. Despite the rarity of PTL NOS, clinicians as well as dermatopathologists and pathologists should be familiar with these rare CTC, especially since most of these lymphomas exhibit an unfavourable prognosis. Immediate intense treatment with multiagent chemotherapy and hematopoietic stem cell transplantation is indicated in patients with PTL NOS. This review focuses on the clinicopathological aspects, the diagnostic criteria and the classification of the rare subtypes of PTL and PTL NOS.

Thirty years of progress in cutaneous lymphoma research.

Primary cutaneous lymphomas are a heterogeneous group of T-cell and B-cell neoplasms that present in the skin without any evidence of extracutaneous disease at the time of diagnosis. In 1980 primary cutaneous lymphomas other than mycosis fungoides, Sezary syndrome and some related disorders, collectively termed cutaneous T-cell lymphoma had not yet been recognized. This historic review describes the history of cutaneous lymphoma research in Europe over the last thirty years. European collaborative studies by dermatologists and pathologists, often coordinated by the European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Group, resulted in the definition of new types of cutaneous T-cell lymphomas (CTCL) and cutaneous B-cell lymphomas (CBCL), and the development of consensus classifications for primary cutaneous lymphomas (EORTC classification; WHO-EORTC classification; WHO classification 2008), which resulted in better diagnosis and treatment of these diseases. More recent activities described herein are the development of guidelines for staging, treatment and the design of clinical trials, often in close collaboration with the International Society for Cutaneous Lymphomas, the formation of an EORTC CTCL trials platform and attempts to translate the results of molecular genetic studies into clinical practise. In this review the importance of a multidisciplinary approach and continued international collaboration not only in clinical trials and guideline development, but also in basic research is emphasized.