IRF4 Gene Rearrangements Define a Subgroup of CD30-Positive Cutaneous T-Cell Lymphoma: A Study of 54 Cases

Primary cutaneous CD30+ lymphoproliferative disorders with DUSP22 translocation

Primary cutaneous CD30+ lymphoproliferative disorders (LPD) encompass a broad category of clonal T cell proliferations with varied clinical presentations. Classically, lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (ALCL) have been recognized as distinct clinicopathological entities according to their differing clinical features. Recently, a subset of LyP and both cutaneous and systemic ALCL have been shown to carry a DUSP22 translocation [1-3], a defining molecular feature for the novel entity "LyP with DUSP22t" [1]. In cutaneous biopsies, both primary cutaneous DUSP22-translocated ALCL and LyP with DUSP22 rearrangements are characterized by a biphasic pattern with significant small cell epidermotropism. A distinct protein expression profile with preserved T Cell Receptor (TCR) expression, positivity for CD30, LEF1, HLA, and CD58, and negativity for cytotoxic marker expression as well as phospho-STAT3 protein is consistently found in these cases.

Prognostic factors for primary cutaneous anaplastic large-cell lymphoma: a multicentre retrospective study from Japan

BACKGROUND

The clinical implications of DUSP22 rearrangement and the association between DUSP22 rearrangement and lymphoid enhancer-binding factor 1 (LEF1) expression pattern in CD30+ cutaneous T-cell lymphomas (CTCLs) are unknown.

OBJECTIVES

This study assessed the incidence of DUSP22 rearrangement and its clinical and immunohistochemical implications in primary cutaneous anaplastic large-cell lymphoma (pcALCL), lymphomatoid papulosis (LyP) and CD30+ mycosis fungoides with large-cell transformation (MF-LCT), focusing especially on the association with the prognosis and LEF1 expression pattern. Prognostic factors of pcALCL were also examined.

METHODS

We conducted a multicentre retrospective study including patients with pcALCL, LyP and MF-LCT diagnosed between 1 January 2000 and 31 December 2018 in Japan. Baseline data at diagnosis, treatment course, overall survival (OS) and disease-specific survival (DSS) were collected. Immunohistochemical analysis and fluorescence in situ hybridization to detect DUSP22 and TP63 rearrangement were performed using skin samples at diagnosis. We investigated the association between staining pattern and these gene rearrangements. We also assessed the prognostic implications of clinical status, immunohistochemical results and the presence of gene rearrangements.

RESULTS

DUSP22 rearrangement was detected in 50% (11 of 22) of cases of pcALCL, but not in any cases with LyP (0 of 14) or MF-LCT (0 of 11). TP63 rearrangement was not detected in any case. Clinically, patients with pcALCL with DUSP22 rearrangement did not tend to develop ulcers (P = 0.081). There was no significant association between DUSP22 rearrangement status and immunohistochemical results, including LEF1 expression pattern. T3 stage and the presence of lower limb lesions were significantly associated with shorter OS (P = 0.012 and 0.021, respectively, by log-rank test). Similarly, they were significantly correlated with shorter DSS (P = 0.016 and 0.0001, respectively).

CONCLUSIONS

DUSP22 rearrangement is relatively specific to pcALCL among CD30+ CTCLs in Japan. Although the LEF1 expression pattern was not related to DUSP22 rearrangement in pcALCL, there was no rearrangement if LEF1 was not expressed. We confirmed that T3 stage and the lower limb involvement were significantly associated with decreased OS and DSS. The presence or absence of lower limb lesions should be included in T-stage subcategorization in the future.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

Differential molecular programs of cutaneous anaplastic large cell lymphoma and CD30-positive transformed mycosis fungoides

Background

Discriminating between cutaneous anaplastic large cell lymphoma (cALCL) and CD30-positive transformed mycosis fungoides (CD30+ TMF) is challenging, particularly when they arise in the context of pre-existing mycosis fungoides. The development of molecular diagnostic tools was hampered by the rarity of both diseases and the limited understanding of their pathogenesis.

Methods

In this study, we established a cohort comprising 25 cALCL cases and 25 CD30+ TMF cases, with transcriptomic data obtained from 31 samples. We compared the clinicopathological information and investigated the gene expression profiling between these two entities. Furthermore, we developed an immunohistochemistry (IHC) algorithm to differentiate these two entities clinically.

Results

Our investigation revealed distinct clinicopathological features and unique gene expression programs associated with cALCL and CD30+ TMF. cALCL and CD30+ TMF displayed marked differences in gene expression patterns. Notably, CD30+ TMF demonstrated enrichment of T cell receptor signaling pathways and an exhausted T cell phenotype, accompanied by infiltration of B cells, dendritic cells, and neurons. In contrast, cALCL cells expressed high levels of HLA class II genes, polarized towards a Th17 phenotype, and exhibited neutrophil infiltration. An IHC algorithm with BATF3 and TCF7 staining emerged as potential diagnostic markers for identifying these two entities.

Conclusions

Our findings provide valuable insights into the differential molecular signatures associated with cALCL and CD30+ TMF, which contribute to their distinct clinicopathological behaviors. An appropriate IHC algorithm could be used as a potential diagnostic tool.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

ALK-negative anaplastic large cell lymphoma with DUSP22 rearrangement has distinctive disease characteristics with better progression-free survival: a LYSA study

ALK-negative anaplastic large cell lymphoma (ALCL) comprises subgroups harboring rearrangements of DUSP22 (DUSP22- R) or TP63 (TP63-R). Two studies reported 90% and 40% 5-year overall survival (OS) rates in 21 and 12 DUSP22-R/TP63- not rearranged (NR) patients, respectively, making the prognostic impact of DUSP22-R unclear. Here, 104 newly diagnosed ALK-negative ALCL patients (including 37 from first-line clinical trials) from the LYSA TENOMIC database were analyzed by break-apart fluorescence in situ hybridization assays for DUSP22-R and TP63-R. There were 47/104 (45%) DUSP22-R and 2/93 (2%) TP63-R cases, including one DUSP22-R/TP63-R case. DUSP22-R tumors more frequently showed CD3 expression (62% vs. 35%, P=0.01), and less commonly a cytotoxic phenotype (27% vs. 82%; P<0.001). At diagnosis, DUSP22- R ALCL patients more frequently had bone involvement (32% vs. 13%, P=0.03). The patient with DUSP22-R/TP63-R ALCL had a rapidly fatal outcome. After a median follow-up of 4.9 years, 5-year progression-free survival (PFS) and OS rates of 84 patients without TP63-R treated with curative-intent anthracycline-based chemotherapy were 41% and 53%, respectively. According to DUSP22 status, 5-year PFS was 57% for 39 DUSP22-R versus 26% for 45 triple-negative (DUSP22-NR/TP63-NR/ALK-negative) patients (P=0.001). The corresponding 5-year OS rates were 65% and 41%, respectively (P=0.07). In multivariate analysis, performance status and DUSP22 status significantly affected PFS, and distinguished four risk groups, with 4-year PFS and OS ranging from 17% to 73% and 21% to 77%, respectively. Performance status but not DUSP22 status influenced OS. The use of brentuximab vedotin in relapsed/refractory patients improved OS independently of DUSP22 status. Our findings support the biological and clinical distinctiveness of DUSP22- R ALK-negative ALCL. Its relevance to outcome in patients receiving frontline brentuximab vedotin remains to be determined.

Anaplastic Large Cell Lymphomas With The 6p25.3 Rearrangement Are A Heterogeneous Group Of Tumours With A Diverse Molecular Background

ALK-negative anaplastic large cell lymphoma (ALCL) cases with 6p25.3 rearrangement are characterized by peculiar morphological and immunohistochemical features compare to 6p25.3-negative ALK-negative ALCL cases. A subgroup of 6p25.3-positive ALK-negative ALCL cases show the t(6,7)(p25.3;q32.3) rearrangement. Aims: To analyse the differences between 6p25.3-rearranged cases with and without t(6,7)(p25.3;q32.3). Using RNA-sequencing we studied a series of 17 samples showing 6p25.3-rearrangement, identified by FISH, consisting of seven systemic and eight primary cutaneous cases including two examples of secondary skin involvement by systemic ALCL. RNA-sequencing exclusively detected a translocation involving a gene in the 6p25.3 region (either IRF4 or DUSP22) in 7/14 cases (50%). In six of these seven cases the partner proved to be the LINC-PINT region in chromosome 7, while an EXOC2::DUSP22 rearrangement was found in one case. All cases but one were primary cutaneous ALCLs. They all were CD3 positive and BCL2 negative, while most of them expressed p-STAT3. On the contrary, cases without the t(6,7)(p25.3;q32.3) were mainly systemic (71%, 5/7) against just two pcALCL. In general, they lose CD3 (50% positive) and p-STAT3 (25% positive) expression, being all of them BCL2 positive. Moreover, in 60% of them other gene fusions were found. At the transcriptional level, they were characterized by the overexpression of TCF3 (TCF7L1/E2A), DLL3, CD58 and BCL2 genes. 75%(6/8) of pcALCL with 6p25.3 rearrangement featured the so-called "biphasic morphologic pattern, which was not found in cutaneous involvement from systemic ALCL. 83% (5/6) of the pcALCL cases with the "biphasic morphologic pattern" showed the t(6,7)(p25.3;q32.3) rearrangement. ALK-negative ALCL cases with 6p25.3 rearrangement are a subgroup of tumours that are heterogeneous with respect to the presence or absence of the t(6,7)(p25.3;q32.3) translocation.

Lymphomatoid papulosis with DUSP22-IRF4 rearrangement: A case report and literature review

Lymphomatoid papulosis (LyP) with DUSP22-IRF4 rearrangement is a rare, recently described variant of LyP histopathologically characterized by a biphasic growth pattern, with epidermotropic small-to-medium-sized atypical T-cells and dermal large and transformed T-cells diffusely expressing CD30. LyP with DUSP22-IRF4 rearrangement can mimic other cutaneous lymphoproliferative disorders, particularly primary cutaneous anaplastic large cell lymphoma (PCALCL) or transformed mycosis fungoides (MF). Unlike PCALCL or transformed MF, LyP with DUSP22-IRF4 rearrangement shows an indolent clinical behavior, with frequent spontaneous regression of untreated lesions. Thus, it is important to recognize this rare variant of LyP to avoid misclassification, which may potentially lead to unnecessarily aggressive patient management. To our knowledge, only 13 cases of LyP with DUSP22-IRF4 rearrangement have been reported to date in the English literature. Herein, we describe an additional case of LyP with DUSP22-IRF4 rearrangement in a 63-year-old man and provide a comprehensive literature review with regards to the clinical, histopathologic, and molecular features of this novel entity.

Recent advances in cutaneous lymphoma-implications for current and future classifications

The Revised European-American Classification of mature lymphoid neoplasms published in 1994 and the 2001, 2008 and 2016 WHO classifications that followed, were the product of international collaboration and consensus amongst haematopathologists, geneticists, molecular scientists and clinicians. Primary cutaneous lymphomas were fully incorporated into this process following the publication of the WHO-EORTC classification of cutaneous lymphomas in 2005. The definition, diagnostic criteria and recommended studies for primary cutaneous lymphoma continue to be refined. The 2022 International Consensus Classification represents the most recent update and an overview of all the main entities presenting primarily in the skin, together with the major changes in classification, are summarized herein. Primary cutaneous marginal zone lymphoma is segregated from other extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma) and downgraded to a lymphoproliferative disorder in line with its markedly indolent behaviour. In addition, two subtypes are recognised, based largely but not exclusively on whether they are heavy chain class-switched or IgM positive. Similarly, in keeping with a trend to greater conservatism, primary cutaneous acral CD8 positive T cell lymphoma is now also classified as a lymphoproliferative disorder. In addition, significant new insights into the biology of primary cutaneous lymphoma have also recently been forthcoming and will be presented. These studies have enhanced our knowledge of genetic, epigenetic and transcriptional changes in this group of diseases. They not only identify potential targets for novel therapies, but also raise as yet unanswered questions as to how we categorise cutaneous lymphomas, particularly with respect to relationships with similar lymphomas at extracutaneous sites.

IRF4 as an Oncogenic Master Transcription Factor

Simple Summary

Master transcription factors regulate essential developmental processes and cellular maintenance that characterize cell identity. Many of them also serve as oncogenes when aberrantly expressed or activated. IRF4 is one of prime examples of oncogenic master transcription factors that has been implicated in various mature lymphoid neoplasms. IRF4 forms unique regulatory circuits and induces oncogenic transcription programs through the interactions with upstream pathways and binding partners.

Abstract

IRF4 is a transcription factor in the interferon regulatory factor (IRF) family. Since the discovery of this gene, various research fields including immunology and oncology have highlighted the unique characteristics and the importance of IRF4 in several biological processes that distinguish it from other IRF family members. In normal lymphocyte development and immunity, IRF4 mediates critical immune responses via interactions with upstream signaling pathways, such as the T-cell receptor and B-cell receptor pathways, as well as their binding partners, which are uniquely expressed in each cell type. On the other hand, IRF4 acts as an oncogene in various mature lymphoid neoplasms when abnormally expressed. IRF4 induces several oncogenes, such as MYC, as well as genes that characterize each cell type by utilizing its ability as a master regulator of immunity. IRF4 and its upstream factor NF-κB form a transcriptional regulatory circuit, including feedback and feedforward loops, to maintain the oncogenic transcriptional program in malignant lymphoid cells. In this review article, we provide an overview of the molecular functions of IRF4 in mature lymphoid neoplasms and highlight its upstream and downstream pathways, as well as the regulatory circuits mediated by IRF4.

Genetic alterations and oxidative stress in T cell lymphomas

T cell lymphomas encompass a diverse group of Non-Hodgkin lymphomas with a wide spectrum of clinical, immunological and pathological manifestations. In the last two decades there has been a progress in our understanding of the cell of origin, genetic abnormalities and their impact on behaviour in T cell lymphomas. Genetic alterations are one of the critical drivers of the pathogenesis of T cell lymphoma. Disease progression has been correlated with multiple genetic abnormalities where malignant clones arise primarily out of the host immune surveillance arsenal. There are many cellular processes involved in disease development, and some of them are T cell signaling, differentiation, epigenetic modifications, and immune regulation. Modulation of these crucial pathways via genetic mutations and chromosomal abnormalities possessing either point or copy number mutations helps tumor cells to develop a niche favourable for their growth via metabolic alterations. Several metabolic pathways especially regulation of redox homeostasis is critical in pathogenesis of lymphoma. Disruption of redox potential and induction of oxidative stress renders malignant cells vulnerable to mitochondrial damage and triggers apoptotic pathways causing cell death. Targeting genetic abnormalities and oxidative stress along with current treatment regime have the potential for improved therapeutics and presents new combination approaches towards selective treatment of T cell lymphomas.

Lineage- and Stage-specific Oncogenicity of IRF4

Dysregulation of transcription factor genes represents a unique molecular etiology of hematological malignancies. A number of transcription factors that play a role in hematopoietic cell development, lymphocyte activation or their maintenance have been identified as oncogenes or tumor suppressors. Many of them exert oncogenic abilities in a context-dependent manner by governing the key transcriptional program unique to each cell type. IRF4, a member of the interferon regulatory factor (IRF) family, acts as an essential regulator of the immune system and is a prime example of a stage-specific oncogene. The expression and oncogenicity of IRF4 are restricted to mature lymphoid neoplasms, while IRF4 potentially serves as a tumor suppressor in other cellular contexts. This is in marked contrast to its immediate downstream target, MYC, which can cause cancers in a variety of tissues. In this review article, we provide an overview of the roles of IRF4 in the development of the normal immune system and lymphoid neoplasms and discuss the potential mechanisms of lineage- and stage-specific oncogenicity of IRF4.

Anaplastic Large Cell Lymphoma: Molecular Pathogenesis and Treatment

Simple Summary

Anaplastic large cell lymphoma is a rare type of disease that occurs throughout the world and has four subtypes. A summary and comparison of these subtypes can assist with advancing our knowledge of the mechanism and treatment of ALCL, which is helpful in making progress in this field.

Abstract

Anaplastic large cell lymphoma (ALCL) is an uncommon type of non-Hodgkin’s lymphoma (NHL), as well as one of the subtypes of T cell lymphoma, accounting for 1 to 3% of non-Hodgkin’s lymphomas and around 15% of T cell lymphomas. In 2016, the World Health Organization (WHO) classified anaplastic large cell lymphoma into four categories: ALK-positive ALCL (ALK+ALCL), ALK-negative ALCL (ALK−ALCL), primary cutaneous ALCL (pcALCL), and breast-implant-associated ALCL (BIA-ALCL), respectively. Clinical symptoms, gene changes, prognoses, and therapy differ among the four types. Large lymphoid cells with copious cytoplasm and pleomorphic characteristics with horseshoe-shaped or reniform nuclei, for example, are found in both ALK+ and ALK−ALCL. However, their epidemiology and pathogenetic origins are distinct. BIA-ALCL is currently recognized as a new provisional entity, which is a noninvasive disease with favorable results. In this review, we focus on molecular pathogenesis and management of anaplastic large cell lymphoma.

Oncogenic Mutations and Gene Fusions in CD30-Positive Lymphoproliferations and Clonally Related Mycosis Fungoides Occurring in the Same Patients

The emergence of a common progenitor cell has been postulated for the association of CD30-positive lymphoproliferative disease (LPD) and mycosis fungoides (MF) within the same patient. Up to now, no comprehensive analysis has yet addressed the genetic profiles of such concurrent lymphoma subtypes. We aimed to delineate the molecular alterations of clonally related CD30-positive LPD and MF occurring in the same two patients. We analyzed the molecular profile of 16 samples of two patients suffering both from CD30-positive LPD and MF being obtained over a time course of at least 5 years. To detect oncogenic mutations, we applied targeted sequencing technologies with a hybrid capture-based DNA library preparation approach, and for the identification of fusion transcripts, an anchored multiplex PCR enrichment kit was used. In all samples of CD30-positive LPD and MF, oncogenic fusions afflicting the Jak/signal transducer and activator of transcription signaling pathway were present, namely NPM1‒TYK2 in patient 1 and ILF3‒JAK2 in patient 2. Additional signal transducer and activator of transcription 5A gene STAT5A mutations exclusively occurred in lesions of CD30-positive LPD in one patient. CD30-positive LPD and MF may share genetic events when occurring within the same patients. Constitutive activation of the Jak/signal transducer and activator of transcription signaling pathway may play a central role in the molecular pathogenesis of both entities.

RNA Sequencing of Primary Cutaneous and Breast-Implant Associated Anaplastic Large Cell Lymphomas Reveals Infrequent Fusion Transcripts and Upregulation of PI3K/AKT Signaling via Neurotrophin Pathway Genes

Simple Summary

Cutaneous and breast implant-associated anaplastic large-cell lymphomas are usually localized neoplasms with an indolent clinical course compared to systemic ALCL. However comparative analyses of the molecular features of these two entities have not yet been reported. We performed targeted RNA sequencing, which revealed that fusion transcripts, although infrequent, might represent additional pathogenetic events in both diseases. We also found that these entities display upregulation of the PI3K/Akt pathway and show enrichment in genes of the neurotrophin signaling pathway. These findings advance our knowledge regarding the pathobiology of cALCL and BI-ALCL and point to additional therapeutic targets.

Abstract

Cutaneous and breast implant-associated anaplastic large-cell lymphomas (cALCLs and BI-ALCLs) are two localized forms of peripheral T-cell lymphomas (PTCLs) that are recognized as distinct entities within the family of ALCL. JAK-STAT signaling is a common feature of all ALCL subtypes, whereas DUSP22/IRF4, TP63 and TYK gene rearrangements have been reported in a proportion of ALK-negative sALCLs and cALCLs. Both cALCLs and BI-ALCLs differ in their gene expression profiles compared to PTCLs; however, a direct comparison of the genomic alterations and transcriptomes of these two entities is lacking. By performing RNA sequencing of 1385 genes (TruSight RNA Pan-Cancer, Illumina) in 12 cALCLs, 10 BI-ALCLs and two anaplastic lymphoma kinase (ALK)-positive sALCLs, we identified the previously reported TYK2-NPM1 fusion in 1 cALCL (1/12, 8%), and four new intrachromosomal gene fusions in 2 BI-ALCLs (2/10, 20%) involving genes on chromosome 1 (EPS15-GNG12 and ARNT-GOLPH3L) and on chromosome 17 (MYO18A-GIT1 and NF1-GOSR1). One of the two BI-ALCL samples showed a complex karyotype, raising the possibility that genomic instability may be responsible for intra-chromosomal fusions in BI-ALCL. Moreover, transcriptional analysis revealed similar upregulation of the PI3K/Akt pathway, associated with enrichment in the expression of neurotrophin signaling genes, which was more conspicuous in BI-ALCL, as well as differences, i.e., over-expression of genes involved in the RNA polymerase II transcription program in BI-ALCL and of the RNA splicing/processing program in cALCL.

Targeted Deep Sequencing of Mycosis Fungoides Reveals Intracellular Signaling Pathways Associated with Aggressiveness and Large Cell Transformation

INTRODUCTION

Large-cell transformation (LCT) of mycosis fungoides (MF) has been associated with a higher risk of relapse and progression and, consequently, restricted prognosis. Its molecular pathogenesis has not been elucidated yet.

MATERIALS AND METHODS

In order to address molecular mechanisms of LCT, we performed hybrid capture panel-based sequencing of skin biopsies from 10 patients suffering from MF with LCT versus 17 patients without LCT including follow-up biopsies during clinical course, respectively (51 samples in total). The analyzed patients were attributed to three different groups based on the presence of LCT and clinical behavior.

RESULTS

While indolent MF cases without LCT did not show pathogenic driver mutations, a high rate of oncogenic alterations was detected in patients with LCT and aggressive clinical courses. Various genes of different oncogenic signaling pathways, including the MAPK and JAK-STAT signaling pathways, as well as epigenetic modifiers were affected. A high inter-individual and distinctive intra-individual mutation diversity was observed. Oncogenic RAS mutations were exclusively detected in patients with LCT.

CONCLUSION

Our data demonstrate that LCT transition of MF is associated with increased frequency of somatic mutations in cancer-associated genes. In particular, the activation of RAS signaling-together with epigenetic dysregulation-may crucially contribute to the molecular pathogenesis of the LCT phenotype, thus conveying its adverse clinical behavior.

Patch/plaque mycosis-fungoides-like presentations of DUSP22-translocated T-cell lymphomas

The DUSP22-IRF4 gene rearrangement results in downregulation of DUSP22, a presumed tumor suppressor in T-cell lymphomagenesis. It has been described in some cases of primary cutaneous and systemic anaplastic large-cell lymphoma, lymphomatoid papulosis, and transformed mycosis fungoides. Here we describe two patients with clinical lesions resembling patch/plaque mycosis fungoides that did not meet WHO criteria for large-cell transformation on histopathology yet showed a DUSP22 translocation. One patient who had a history of systemic anaplastic large-cell lymphoma with DUSP22 translocation presented with cutaneous involvement by his systemic lymphoma along with lymphomatoid papulosis and mycosis-fungoides-like lesions, all showing an identical immunophenotype and T-cell clone. These cases expand the spectrum of DUSP22-rearranged lymphomas to include mycosis-fungoides-like presentations without large-cell transformation.

Genetic and epigenetic insights into cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL) constitute a heterogeneous group of non-Hodgkin T-cell lymphomas that present in the skin. In recent years significant progress has been made in the understanding of the pathogenesis of CTCL. Progress in CTCL classifications combined with technical advances, in particular next generation sequencing (NGS), enabled a more detailed analysis of the genetic and epigenetic landscape and transcriptional changes in clearly defined diagnostic entities. These studies not only demonstrated extensive heterogeneity between different CTCL subtypes but also identified recurrent alterations that are highly characteristic for diagnostic subgroups of CTCL. The identified alterations in particular involve epigenetic remodelling, cell cycle regulation, and the constitutive activation of targetable, oncogenic pathways. In this respect, aberrant JAK-STAT signaling is a recurrent theme, however not universal for all CTCL and with seemingly different underlaying causes in different entities. A number of the mutated genes identified are potentially actionable targets for the development of novel therapeutic strategies. Moreover, these studies have produced an enormous amount of information that will be critically important for the further development of improved diagnostic and prognostic biomarkers that can assist in the clinical management of CTCL patients. In the present review the main findings of these studies in relation to their functional impact on the malignant transformation process are discussed for different subtypes of CTCL.

Cytokines, Genetic Lesions and Signaling Pathways in Anaplastic Large Cell Lymphomas

ALCL is a tumor of activated T cells and possibly innate lymphoid cells with several subtypes according to clinical presentation and genetic lesions. On one hand, the expression of transcription factors and cytokine receptors triggers signaling pathways. On the other hand, ALCL tumor cells also produce many proteins including chemokines, cytokines and growth factors that affect patient symptoms. Examples are accumulation of granulocytes stimulated by IL-8, IL-17, IL-9 and IL-13; epidermal hyperplasia and psoriasis-like skin lesions due to IL-22; and fever and weight loss in response to IL-6 and IFN-γ. In this review, we focus on the biology of the main ALCL subtypes as the identification of signaling pathways and ALCL-derived cytokines offers opportunities for targeted therapies.

Diagnosis and prognostic stratification of cutaneous lymphoma

Primary cutaneous lymphomas are a heterogenous group of non-Hodgkin's lymphoma of both T/natural killer-cell and B-cell origin and defined to primarily present in the skin without extracutaneous involvement at diagnosis. In contrast to nodal non-Hodgkin's lymphoma, cutaneous T-cell lymphomas (CTCL) are more generally seen than cutaneous B-cell lymphomas (CBCL). CTCL and CBCL have various subtypes and each subtype has specifically characteristic clinical, pathological, and prognostic features. The diagnostic methods and staging evaluation of cutaneous lymphomas is mostly common in various guidelines created by professional societies. The diagnosis is made comprehensively based on clinical, pathological, laboratory, radiological, and genetic findings. On the other hand, definite prognostic stratification has not been completely established yet in most cutaneous lymphomas. This article focuses on the general and novel diagnostic methods and the current findings about prognostic factors and stratification in cutaneous lymphomas.

DUSP22 Rearrangement in primary cutaneous T-cell Lymphoma with features intermediate between Mycosis Fungoides, Anaplastic Large-cell Lymphoma and Lymphomatoid Papulosis

A 79-year-old man with a long-standing history of eczema with no other remarkable medical history came to our hospital complaining of a round, non-ulcerated, 3-cm-diameter, tumoral nodule of sudden growth (Figure 1A, 1B). Histological study revealed a CD30+, CD3+ biphasic lymphoid infiltrate with large cells in the dermis and smaller lymphocytes that exhibited a striking epidermotropism that was also present in the contiguous epidermis, where it had a pagetoid pattern (Figure 2A, 2B, 2C, 2D, 2E). TCR-ß was positive and CD8 was focally and weakly positive. CD4, CD20, ALK, TIA1, Perforin, Granzyme, PSTAT3 and TCR-γ were all negative.

Primary cutaneous anaplastic large-cell lymphoma with 6p25.3 rearrangement exhibits a biphasic histopathologic pattern: Two case reports and literature review

BACKGROUND

Primary cutaneous CD30+ lymphoproliferative diseases are the second most common group of cutaneous T-cell lymphomas, including lymphomatoid papulosis (LyP), primary cutaneous anaplastic large-cell lymphoma (pcALCL), and borderline cases. These diseases form a spectrum and may show overlapping histopathological, phenotypic, and genetic features. In the 2016 WHO classification, LyP with 6p25.3 rearrangement was introduced as a rare new subtype of LyP and showed distinctive clinicopathological features. The striking biphasic histopathologic pattern presented with larger transformed lymphocytes diffusely infiltrating the dermis and smaller atypical cells infiltrating the epidermis as in pagetoid reticulosis.

METHODS

Herein we report two cases of pcALCL with rearrangement involving the DUSP22-IRF4 locus on 6p25.3 that show the same particular biphasic histopathologic pattern. We review the literature regarding five similar reported cases and discuss the clinical, pathologic immunotype and follow-up features.

RESULTS

Our findings suggest that the biphasic histopathologic pattern is not a unique characteristic of LyP with 6p25.3 rearrangement.

CONCLUSION

Cutaneous CD30+ lymphoproliferative diseases with 6p25.3 rearrangement may have the same biphasic histopathological pattern and favorable prognosis, although a variety of clinical manifestations ranging from LyP to pcALCL and even anaplastic lymphoma kinase negative systemic ALCL with secondary cutaneous involvement may be observed.

Self-regressing oral CD30-positive, EBV-negative, T-cell lymphoproliferative lesions. A poorly understood process highlighted by ominous clinicopathologic features and indolent behavior

OBJECTIVE

Intraoral, primary, CD30-positive (CD30⁺) T-cell lymphoproliferative disorders (TLPDs) are uncommon, and their clinicopathologic presentation and management can vary and may be challenging. Herein, we present a retrospective study of 4 examples of self-regressing primary CD30⁺ TLPD affecting the gingiva.

STUDY DESIGN

Archived files were retrospectively reviewed for oral CD30⁺ TLPDs featuring (1) proper immunohistochemical documentation, (2) Epstein-Barr virus negativity, (3) adequate follow-up information corroborating regression, and (4) no history of hematopoietic malignancy or related-mucocutaneous disease.

RESULTS

Three women and 1 man (age range, 55-82 years; mean, 68.3 years) presented with rapidly growing gingival ulcers. Microscopic evaluation revealed diffuse infiltration by sheets of large, atypical cells admixed with lymphocytes and eosinophils, showing angiocentric distribution, focal neurotropism, and muscle infiltration. The lesional cells consistently stained for CD3 and CD30 and were variably immunoreactive against CD2, CD4, CD5, CD7, and CD8, but were negative for ALK1 and EBV-encoded small RNA. TCR-γ gene rearrangement studies revealed a monoclonal T-cell population in 1 case. All lesions showed complete regression 2 to 8 weeks postoperatively (mean follow-up, 4.5 weeks).

CONCLUSIONS

Notwithstanding their alarming clinicopathologic appearance, there are CD30⁺ TLPDs confined to the oral cavity that have an indolent course. However, clinical staging is essential to exclude aggressive systemic malignancy.

B cell lymphoma with IRF4 rearrangement: A clinicopathological study of 13 cases

Interferon regulatory factor 4 (IRF4) rearrangement is commonly detected in patients with a range of lymphoproliferative malignancies, including myelomas, large B cell lymphomas and low-grade B cell neoplasms. However, IRF4 rearrangement is generally a relatively rare finding in these latter two cancer types. In the present article, we describe and summarize the clinicopathological and genetic features of 13 cases of B cell lymphoma with IRF4 rearrangement, including 12 cases of large B cell lymphoma and one case of low-grade lymphoma exhibiting such rearrangement. These cases were detected in six females and seven males between 14 and 71 years of age. From a morphological perspective, large B cell lymphoma tumors included in this analysis exhibited large neoplastic cells in diffuse or follicular patterns, while the case of low-grade lymphoma mainly composed of small lymphocytes. All analyzed cases exhibited a split in the IRF4 gene consistent with IRF4 translocation. Three of six analyzed large B cell lymphoma cases harbored IGLL5 mutations. Mutations in SAMHD1 were detected in the low-grade lymphoma with IRF4 rearrangement case. In summary, our results offer further insight into the morphological and molecular heterogeneity of cases of B cell lymphoma exhibiting IRF4 rearrangements.

Recurrent Oncogenic JAK and STAT Alterations in Cutaneous CD30-Positive Lymphoproliferative Disorders

The group of cutaneous CD30-positive lymphoproliferative disorders (LPD) comprises two different entities, namely lymphomatoid papulosis (LyP) and cutaneous anaplastic large T-cell lymphoma (cALCL). LyP constitutes a benign lymphoproliferation with spontaneously regressing papules, whereas cALCL presents with solitary or multiple skin tumors with a low propensity to disseminate. To elucidate the hitherto largely unknown molecular pathogenesis of these entities, we performed comprehensive next-generation sequencing in a well-characterized cohort of 12 patients. Considering the low tumor cell content of LyP, we applied targeted sequencing technologies with a hybrid capture-based DNA library preparation approach and for the identification of fusion transcripts an anchored multiplex PCR enrichment kit. As the major finding, we detected, in 50% of LPD, genetic events that implied a constitutively activated Janus kinase-signal transducer and activator of transcription signaling (JAK-STAT) pathway in these entities. The identified molecular aberrations comprised either pathogenic STAT mutations or oncogenic fusion transcripts comprising effector domains of JAK. With respect to LyP, we report to our knowledge such previously unreported genetic aberrations in this specific entity. The detection of these convergent aberrations within the JAK-STAT signaling pathway deciphers common potential driving mechanisms of lymphomagenesis within LPD being shared between LyP and cALCL. Moreover, the presence of these oncogenic alterations paves the way to develop novel personalized treatment strategies.

Effect of 50-Hz Magnetic Fields on Serum IL-1β and IL-23 and Expression of BLIMP-1, XBP-1, and IRF-4

Investigations demonstrated that magnetic fields (MFs) change cytokine production and expression of some immune system genes. This alteration can affect the immune system function and may lead to some diseases. Therefore, this study investigated two important inflammatory cytokines, i.e., IL-1β and IL-23 at two phases of pre- and post-immunization of the immune system. In addition, the expressions of three important genes in the humoral immunity, i.e., B lymphocyte-induced maturation protein-1 (BLIMP-1), X-box-binding protein-1 (XBP-1), and interferon regulatory factor-4 (IRF-4) were evaluated at post-immunization phase. Eighty adult male rats were divided into four experimental groups and a control. The experimental groups were exposed to 50 -Hz MFs with magnetic flux densities of 1, 100, 500, and 2000 μT, 2 h/day for 2 months. The animals were injected by human serum albumin (100 μg/rat) on days 31, 44, and 58 of exposure. The cytokine levels in serum were measured with enzyme-linked immunosorbent assay (ELISA), and the expression of genes was evaluated with reverse transcription quantitative polymerase chain reaction (RT-qPCR). Serum IL-1β was decreased at pre-immunization phase after exposure to 1 and 100 μT of 50-Hz MFs. In contrast, serum IL-23 was increased at post-immunization phase in 100 μT group. No change was observed in serum IL-1β and IL-23 in each group at pre-immunization phase compared with post-immunization. Furthermore, exposure to 100 μT downregulated expression of BLIMP-1, XBP-1, and IRF-4. In conclusion, exposure to 50-Hz MFs may decrease inflammation at short time and increase it at longer time exposures. In addition, 50-Hz MF exposure may decrease the humoral immune responses. It seems that 50-Hz MFs cause more alteration in immune system function at lower densities (100 μT).

Pathology and genetics of anaplastic large cell lymphoma

Anaplastic large cell lymphomas are a rare subtype of peripheral/mature T-cell lymphomas which are clinically, pathologically and genetically heterogeneous. Both ALK-positive (ALK+) and ALK-negative (ALK-) ALCL are composed of large lymphoid cells with abundant cytoplasm and pleomorphic features with horseshoe-shaped and reniform nuclei. ALK+ ALCL were considered as a definite entity in the 2008 World Health Organization classification of hematopoietic and lymphoid tissues. ALK-ALCL was included as a provisional entity in the WHO 2008 edition and in the most recent 2017 edition, it is now considered a distinct entity that includes cytogenetic subsets that appear to have prognostic implications (e.g. 6p25 rearrangements at IRF4/DUSP22 locus). ALK+ ALCLs are distinct in epidemiology and pathogenetic origin and should be distinguished from ALK-ALCL, cutaneous ALCL and breast implant associated ALCL which have distinct clinical course and pathogenetic features. Breast implant-associated ALCL is now recognized as a new provisional entity distinct from other ALK-ALCL; notably that it is a noninvasive disease associated with excellent outcome. In this article, we will provide an overview of the salient themes relevant to the pathology and genetic mechanisms in ALCL.

Approach to nodal-based T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of uncommon malignancies derived from mature T cells and usually characterised by an aggressive clinical course. Their clinical presentation, localisation and pattern of dissemination are highly variable, but the majority of cases present as nodal diseases. The recently revised classification of lymphomas has incorporated many new molecular genetic data derived from gene expression profiling and next generation sequencing studies, which refine the definition and diagnostic criteria of several entities. Nevertheless, the distinction of PTCL from various reactive conditions, and the diagnosis of PTCL subtypes remains notably challenging. Here, an updated summary of the clinicopathological and molecular features of the most common nodal-based PTCLs (angioimmunoblastic T-cell lymphoma and other nodal lymphomas derived from follicular T helper cells, anaplastic large cell lymphomas and peripheral T-cell lymphoma, not otherwise specified) is presented. Practical recommendations in the diagnostic approach to nodal T-cell lymphoproliferations are presented, including indications for the appropriate use and interpretation of ancillary studies. Finally, we discuss commonly encountered diagnostic problems, including pitfalls and mimics in the differential diagnosis with various reactive conditions, and the criteria that allow proper identification of distinct PTCL entities.

Recent Advances in Cutaneous T-cell Lymphoma: Diagnostic and Prognostic Considerations

This review describes the latest advances in the diagnosis of cutaneous T-cell lymphoma focusing on the most clinically useful features introduced since the publication of the World Health Organization revision in 2017. Clinical entities described include mycosis fungoides, Sézary syndrome, lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma, primary cutaneous gamma delta T-cell lymphoma, primary cutaneous acral CD8⁺ T-cell lymphoma, primary cutaneous CD4⁺ small/medium T-cell lymphoproliferative disorder, and hydroa-vacciniforme-like lymphoproliferative disorder. Distinguishing histologic clues to diagnosis are discussed, and important molecular advances are described. Key prognostic indicators that may assist clinicians with timely and appropriate management options are presented.

Systemic, primary cutaneous, and breast implant-associated ALK-negative anaplastic large-cell lymphomas present similar biologic features despite distinct clinical behavior

Despite distinct clinical presentation and outcome, systemic, primary cutaneous, and breast implant-associated anaplastic large cell lymphomas (S-, PC-, BI-ALCL) ALK-negative (ALK-) show similar histopathological features including the presence of the "hallmark" cells with horseshoe-shaped nuclei and CD30 protein expression. The purpose was to better characterize these three entities using immunohistochemistry and FISH (Fluorescent in situ hybridization) to identify biomarkers differently expressed and that might be involved in their pathogenesis. Twenty-two S-ALCL ALK-, 13 PC-ALCL, and 2 BI-ALCL were included. Cases were tested for P53, P63, MUM1, MYC, GATA3, p-STAT3, PD1, and PDL1 protein expression and DUP22, TP53, TP63, MYC, and PDL1 chromosomal aberrations. As expected, S-ALCL ALK- patients had adverse outcome compare to PC and BI-ALCL. No difference was observed between the three groups concerning protein expression except for MUM1 that was significantly more frequently expressed in S-ALCL ALK- compared to PC-ALCL. In particular, constitutive activation of the STAT3 pathway and PDL1/PD1 immune-checkpoint expression was present in the three entities. TP53 deletion and PDL1 gene amplification were the commonest cytogenetic alterations and were present in the three entities. None of the studied biological parameters was associated with prognosis. Despite distinct clinical behavior, S-ALCL ALK-, PC-ALCL, and BI-ALCL share similar biological features. Larger series should be investigated with the current approach to determine more precisely the activity and the prognostic value of these biomarkers and pathways in each group.

Molecular Drivers of Breast Implant-Associated Anaplastic Large Cell Lymphoma

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a rare T-cell lymphoproliferative disorder occurring in patients with breast implants. Genomic characterization performed in BIA-ALCL to date has demonstrated qualitatively similar molecular abnormalities to those seen in its more common counterpart [ALK-negative systemic anaplastic large cell lymphoma (sALCL)] including JAK/STAT activation and MYC/TP53 dysregulation. Despite these observed similarities at the molecular level, the outcomes of sALCL and BIA-ALCL are markedly different with sALCL typically associated with an aggressive course and inferior outcomes compared with BIA-ALCL. This review describes the findings of high-throughput sequencing and other genomic characterization to date in BIA-ALCL and the insights these studies have given into the molecular drivers of this rare lymphoma subtype.

Cutaneous Lymphoproliferative Disorders: What's New in the Revised 4th Edition of the World Health Organization (WHO) Classification of Lymphoid Neoplasms

Cutaneous lymphoproliferative disorders remain a challenging aspect of dermatopathology, in part due to the rarity of the entities and extreme variability in clinical outcomes. Although many of the entities remain unchanged, the approach to some of them has changed in the new 2016 classification scheme of the World Health Organization. Chief among these are Epstein-Barr virus-associated lymphoproliferative disorders such as Epstein-Barr virus-associated mucocutaneous ulcer and hydroa vacciniforme-like lymphoproliferative disorder, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma, primary cutaneous acral CD8+ T-cell lymphoma, primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder, and breast implant-associated anaplastic large cell lymphoma. In addition, translocations and gene rearrangements such as those involving the 6p25.3 locus have started to inform diagnosis and classification of anaplastic large cell lymphoma and lymphomatoid papulosis. In this review, we will examine what is new in the diagnostic toolbox of cutaneous lymphoproliferative disorders.

CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies

Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets.

Molecular profiling reveals immunogenic cues in anaplastic large cell lymphomas with DUSP22 rearrangements

Anaplastic large cell lymphomas (ALCLs) are CD30-positive T-cell non-Hodgkin lymphomas broadly segregated into ALK-positive and ALK-negative types. Although ALK-positive ALCLs consistently bear rearrangements of the ALK tyrosine kinase gene, ALK-negative ALCLs are clinically and genetically heterogeneous. About 30% of ALK-negative ALCLs have rearrangements of DUSP22 and have excellent long-term outcomes with standard therapy. To better understand this group of tumors, we evaluated their molecular signature using gene expression profiling. DUSP22-rearranged ALCLs belonged to a distinct subset of ALCLs that lacked expression of genes associated with JAK-STAT3 signaling, a pathway contributing to growth in the majority of ALCLs. Reverse-phase protein array and immunohistochemical studies confirmed the lack of activated STAT3 in DUSP22-rearranged ALCLs. DUSP22-rearranged ALCLs also overexpressed immunogenic cancer-testis antigen (CTA) genes and showed marked DNA hypomethylation by reduced representation bisulfate sequencing and DNA methylation arrays. Pharmacologic DNA demethylation in ALCL cells recapitulated the overexpression of CTAs and other DUSP22 signature genes. In addition, DUSP22-rearranged ALCLs minimally expressed PD-L1 compared with other ALCLs, but showed high expression of the costimulatory gene CD58 and HLA class II. Taken together, these findings indicate that DUSP22 rearrangements define a molecularly distinct subgroup of ALCLs, and that immunogenic cues related to antigenicity, costimulatory molecule expression, and inactivity of the PD-1/PD-L1 immune checkpoint likely contribute to their favorable prognosis. More aggressive ALCLs might be pharmacologically reprogrammed to a DUSP22-like immunogenic molecular signature through the use of demethylating agents and/or immune checkpoint inhibitors.

Successful experience in treating primary cutaneous anaplastic large cell lymphoma occuring with common lesions of the skin and lung tissue

The aim of the study is to present a successful case in treating primary cutaneous anaplastic large cell lymphoma (PCALCL) occurring with common lesions of the skin and lung tissue.Materials and methods. For the verification of the diagnosis in a patient with three types of skin elements (spot, thin plaque with and without ulceration), differential diagnosis was performed between ulcerative pyoderma gangrenosum, PCALCL, large-cell transformation of mycosis fungoides, and secondary skin lesions under the nodal ALK-negtaive ALCL. A complex of studies, including histological, immunohisto - chemical, cytogenetic studies of skin tumor biopsy, allowed the verification of the PCALCL diagnosis. For the treatment of the patient, intensive induction chemotherapy was used followed by high-dose consolidation and autologous transplantation of hematopoietic stem cells.Results. The selected treatment tactics allowed a long-term complete remission of the disease to be achieved in a patient from the poor prognosis group.Conclusion. An algorithm for the differential diagnosis and tactics of treating is presented for a patient with primary anaplastic large cell lymphoma with a widespread skin lesion and extradermal foci.

Molecular alterations and tumor suppressive function of the DUSP22 (Dual Specificity Phosphatase 22) gene in peripheral T-cell lymphoma subtypes

Monoallelic 6p25.3 rearrangements associated with DUSP22 (Dual Specificity Phosphatase 22) gene silencing have been reported in CD30+ peripheral T-cell lymphomas (PTCL), mostly with anaplastic morphology and of cutaneous origin. However, the mechanism of second allele silencing and the putative tumor suppressor function of DUSP22 have not been investigated so far. Here, we show that the presence, in most individuals, of an inactive paralog hampers genetic and epigenetic evaluation of the DUSP22 gene. Identification of DUSP22-specific single-nucleotide polymorphisms haplotypes and fluorescence in situ hybridization and epigenetic characterization of the paralog status led us to develop a comprehensive strategy enabling reliable identification of DUSP22 alterations. We showed that one cutaneous anaplastic large T-cell lymphomas (cALCL) case with monoallelic 6p25.3 rearrangement and DUSP22 silencing harbored exon 1 somatic mutations associated with second allele inactivation. Another cALCL case carried an intron 1 somatic splice site mutation with predicted deleterious exon skipping effect. Other tested PTCL cases with 6p25.3 rearrangement exhibited neither mutation nor deletion nor methylation accounting for silencing of the non-rearranged DUSP22 allele, thus inactivated by a so far unknown mechanism. We also characterized the expression status of four DUSP22 splice variants and found that they are all silenced in cALCL cases with 6p25.3 breakpoints. We finally showed that restoring expression of the physiologically predominant isoform in DUSP22-deficient malignant T cells inhibits cellular expansion by stimulating apoptosis and impairs soft agar clonogenicity and tumorigenicity. This study therefore shows that DUSP22 behaves as a tumor suppressor gene in PTCL.

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphomas comprise a heterogeneous group of diseases characterized by monoclonal proliferations of T lymphocytes primarily involving skin, modified skin appendages, and some mucosal sites. This article addresses the basic clinical, histologic, and immunohistochemical characteristics of this group of diseases, with additional attention to evolving literature on dermoscopy, reflectance confocal microscopy, flow cytometry, and molecular data that may increasingly be applied to diagnostic and therapeutic algorithms in these diseases. Select unusual phenotypes or diagnostic examples of classic phenotypes are demonstrated, and flags for consideration while making a pathologic diagnosis of cutaneous T-cell lymphoma are suggested.

Understanding CD30 biology and therapeutic targeting: a historical perspective providing insight into future directions

CD30 is a member of the tumor necrosis factor receptor superfamily. It is characteristically expressed in certain hematopoietic malignancies, including anaplastic large cell lymphoma and Hodgkin lymphoma, among others. The variable expression of CD30 on both normal and malignant lymphoid cells has focused research efforts on understanding the pathogenesis of CD30 upregulation, its contribution to lymphomagenesis through anti-apoptotic mechanisms, and its effect on cell survival. Given the restriction of CD30 to certain tumor types, the logical extension of this has been to attempt to exploit it as a therapeutic target. The efficacy of naked anti-CD30 antibodies in practice was, however, modest. Moreover, combinations with bacterial toxins and radioimmunoconjugates have also had limited success. The development of the antibody-drug compound brentuximab vedotin (BV), however, has rejuvenated interest in CD30 as a tumor target. Phase I and II clinical trials in Hodgkin lymphoma, peripheral T-cell lymphoma, cutaneous T cell lymphoma, and even CD30-expressing B-cell lymphomas, have shown the compound is well tolerated, but more importantly, able to deliver meaningful disease control even in patients with multiply relapsed or refractory disease. FDA approval has been granted for its use in relapsed Hodgkin lymphoma and systemic anaplastic large cell lymphoma. A recent phase III trial of BV in cutaneous T-cell lymphoma has confirmed its superiority to standard of care therapies. In this manuscript, we explore the history of CD30 as a tumor marker and as a therapeutic target, both in the laboratory and in the clinic, with a view to understanding future avenues for further study.

Molecular analysis of immunoglobulin variable genes supports a germinal center experienced normal counterpart in primary cutaneous diffuse large B-cell lymphoma, leg-type

BACKGROUND

Immunophenotype of primary cutaneous diffuse large B-cell lymphoma, leg-type (PCLBCL-LT) suggests a germinal center-experienced B lymphocyte (BCL2+ MUM1+ BCL6+/-).

OBJECTIVES

As maturation history of B-cell is "imprinted" during B-cell development on the immunoglobulin gene sequence, we studied the structure and sequence of the variable part of the genes (IGHV, IGLV, IGKV), immunoglobulin surface expression and features of class switching in order to determine the PCLBCL-LT cell of origin.

METHODS

Clonality analysis with BIOMED2 protocol and VH leader primers was done on DNA extracted from frozen skin biopsies on retrospective samples from 14 patients. The clonal DNA IGHV sequence of the tumor was aligned and compared with the closest germline sequence and homology percentage was calculated. Superantigen binding sites were studied. Features of selection pressure were evaluated with the multinomial Lossos model.

RESULTS

A functional monoclonal sequence was observed in 14 cases as determined for IGHV (10), IGLV (2) or IGKV (3). IGV mutation rates were high (>5%) in all cases but one (median:15.5%), with superantigen binding sites conservation. Features of selection pressure were identified in 11/12 interpretable cases, more frequently negative (75%) than positive (25%). Intraclonal variation was detected in 3 of 8 tumor specimens with a low rate of mutations. Surface immunoglobulin was an IgM in 12/12 cases. FISH analysis of IGHM locus, deleted during class switching, showed heterozygous IGHM gene deletion in half of cases. The genomic PCR analysis confirmed the deletions within the switch μ region. IGV sequences were highly mutated but functional, with negative features of selection pressure suggesting one or more germinal center passage(s) with somatic hypermutation, but superantigen (SpA) binding sites conservation. Genetic features of class switch were observed, but on the non functional allele and co-existing with primary isotype IgM expression.

CONCLUSION

These data suggest that cell-of origin is germinal center experienced and superantigen driven selected B-cell, in a stage between germinal center B-cell and plasma cell.

Primary gastrointestinal anaplastic large cell lymphoma

Primary gastrointestinal anaplastic large cell lymphoma (GI-ALCL) is rare. We report eight new cases. The median age was 61.5 years (range 10-88), most frequently involving the stomach (n = 3) and small intestine (n = 4). The neoplastic hallmark cells in all cases expressed CD30. Anaplastic lymphoma kinase (ALK) protein was expressed in two cases (25%). By in situ hybridisation, all cases were negative for Epstein-Barr virus and for DUSP22/IRF4 gene translocation. At a median follow-up time of 37.5 months, four patients died of disease, one was alive with disease, and three were disease-free. Our literature review showed that GI-ALCL occurred mainly in older patients and was characterised by a low rate of ALK expression, a high rate of T-cell lineage, and a frequent occurrence in the small intestine. Incorporating our two ALK⁺ GI-ALCL cases together with the four cases in the literature, the median age was 34 years (range 10-56), with four (67%) cases in the small intestine. The six patients were all alive with a median follow-up of 21 months. The 5-year overall survival of our six patients with ALK^- GI-ALCL was 40%, in contrast to 100% with ALK⁺ GI-ALCL. The prognosis for ALK^- GI-ALCL was poor, while that for the ALK⁺ counterparts was good.

Primary cutaneous anaplastic large cell lymphoma

Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a CD30+ lymphoproliferative disorder (LPD) of the skin with a relatively good prognosis in the absence of high-stage disease. CD30+ LPDs comprise approximately 25%-30% of primary cutaneous lymphomas and as a group represent the second most common clonal T-cell neoplasm of the skin behind mycosis fungoides. Diagnosis of PC-ALCL relies strongly on clinicopathologic correlation given the potential morphologic, clinical and molecular overlap with the other cutaneous CD30+ LPD, lymphomatoid papulosis, and more aggressive hematolymphoid neoplasms.

Primary Cutaneous Anaplastic Large-Cell Lymphoma With 6p25.3 Rearrangement in a Cardiac Transplant Recipient: A Case Report and Review of the Literature

Posttransplant lymphoproliferative disorders define an important form of lymphoproliferative disease causally linked with a state of iatrogenic immune dysregulation inherent to the posttransplant setting. Most posttransplant lymphoproliferative disorders are in the context of Epstein-Barr virus-associated B-cell lymphoproliferative disease, most notably diffuse large-cell B-cell lymphoma. A less common variant falls under the rubric of posttransplant T-cell lymphoproliferative disease, which is largely unrelated to Epstein-Barr virus infection. Anaplastic large-cell lymphoma (ALCL) is the most recognized form of posttransplant T-cell lymphoproliferative disease. Although the 6p25.3 translocation is seen in a variety of B-cell lymphoproliferative disorders, this particular translocation in the spectrum of T-cell lymphoproliferative disease is a fairly specific finding pointing toward a diagnosis of primary cutaneous ALCL and a rare subset of lymphomatoid papulosis. This translocation in the peripheral T-cell lymphoma setting serves as a favorable prognostic predictor. We report a case of an 81-year-old heart transplant recipient who developed an expansile neck mass 17 years after his heart transplant. A diagnosis of cutaneous ALCL was subsequently made with cytogenetic analysis yielding the 6p25.3 translocation. The characteristic biphasic morphology of a small-cell epidermotropic neoplastic cell populace in concert with a dermal based large-cell infiltrate characteristic for those cases of ALCL harboring this translocation was seen. After excision of the nodule, his azathioprine was withheld. He is currently alive and well without evidence of disease.