The importance of differentiating between mycosis fungoides with CD30-positive large cell transformation and mycosis fungoides with coexistent primary cutaneous anaplastic large cell lymphoma

Spatially Resolved Transcriptomes of CD30+-Transformed Mycosis Fungoides and Cutaneous Anaplastic Large-Cell Lymphoma

Mycosis fungoides with large-cell transformation (MF-LCT) occurs in a minor proportion of aggressive lesions, which express CD30 similar to primary cutaneous anaplastic large-cell lymphoma (pcALCL). We investigated the differences in spatially resolved transcriptome profiles of MF-LCT and pcALCL using CD30 morphology markers and 28 and 24 regions of interest (ROIs) in MF-LCT and pcALCL, respectively. Differentially expressed genes, pathway analysis, and immune-cell deconvolution by selective analysis of CD30-positive tumor cells and CD30-negative extratumoral areas were undertaken. In CD30-positive ROIs of MF-LCT, 190 differentially expressed genes were upregulated (29 were directly or indirectly associated with extracellular matrix remodeling), whereas 255 differentially expressed genes were downregulated, compared with those of pcALCL. Except for cornified envelope formation and keratinization, all six pathways enriched in CD30-positive ROIs of MF-LCT were associated with extracellular matrix remodeling. In CD30-positive ROIs in MF-LCT compared with those in pcALCL, immune-cell deconvolution revealed significantly increased fibroblasts and M2 macrophages (P = 0.012 and P = 0.023, respectively) but decreased M1 macrophages (P = 0.031). In CD30-negative ROIs in MF-LCT compared with those in pcALCL, memory B (P = 0.021), plasma (P = 0.023), and CD8 memory T (P = 0.001) cells significantly decreased, whereas regulatory T cells (P = 0.024) increased. Predomination of extracellular matrix remodeling pathways and immunosuppressive microenvironment in MF-LCT indicates pathophysiological differences between MF-LCT and pcALCL.

CD30-positive lymphoproliferative disorders-An Australian Clinical Practice Statement from the Peter MacCallum Cancer Centre

The CD30-postive lymphoproliferative disorders, including lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, account for up to 30% of all cutaneous T-cell lymphomas (CTCLs) and are the second most common form of CTCLs after mycosis fungoides. Both conditions differ in their clinical presentations; however, they share the expression of the CD30 antigen as a common immunophenotypic hallmark. There is a wide spectrum of management options depending on factors such as extent of disease, staging and treatment tolerability. This Clinical Practice Statement is reflective of the current clinical practice in Australia.

Single-cell transcriptomics links malignant T cells to the tumor immune landscape in cutaneous T cell lymphoma

Cutaneous T cell lymphoma (CTCL) represents a heterogeneous group of non-Hodgkin lymphoma distinguished by the presence of clonal malignant T cells. The heterogeneity of malignant T cells and the complex tumor microenvironment remain poorly characterized. With single-cell RNA analysis and bulk whole-exome sequencing on 19 skin lesions from 15 CTCL patients, we decipher the intra-tumor and inter-lesion diversity of CTCL patients and propose a multi-step tumor evolution model. We further establish a subtyping scheme based on the molecular features of malignant T cells and their pro-tumorigenic microenvironments: the T_CyEM group, demonstrating a cytotoxic effector memory T cell phenotype, shows more M2 macrophages infiltration, while the T_CM group, featured by a central memory T cell phenotype and adverse patient outcome, is infiltrated by highly exhausted CD8⁺ reactive T cells, B cells and Tregs with suppressive activities. Our results establish a solid basis for understanding the nature of CTCL and pave the way for future precision medicine for CTCL patients.

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.

How I Diagnose Anaplastic Large Cell Lymphoma

OBJECTIVES

This review describes our approach to the diagnosis of all 4 anaplastic large cell lymphoma (ALCL) entities.

METHODS

ALCLs are a group of CD30-positive mature T-cell lymphomas with similar morphologic and phenotypic characteristics but variable clinical and genetic features. They include systemic ALK-positive ALCL, systemic ALK-negative ALCL, primary cutaneous ALCL, and the recently described provisional entity breast implant-associated ALCL.

RESULTS

In cases with classic features, the diagnosis of ALCL is often straightforward. However, variant histology, the importance of clinical history, and multiple antigenic aberrancies all present challenges to accurate diagnosis and subclassification.

CONCLUSIONS

A systematic approach to the diagnosis of ALCL and awareness of potential mimics are critical to avoid misdiagnosis. It is also crucial to correctly identify localized forms of ALCL to avoid classification as systemic ALCL and subsequent overtreatment.

Mapping signal transducer and activator of transcription (STAT) activity in different stages of mycosis fungoides and Sezary syndrome

BACKGROUND

Deregulation of signal transducer and activator of transcription (STAT) signaling is known to participate in the pathogenesis of cutaneous T-cell lymphomas (CTCLs). However, published results regarding STAT expression in different stages of CTCLs are conflicting. The aim of the study was to define the pattern of STAT expression in skin and detect any differences between pruritic and nonpruritic patients but also different stages of disease.

METHODS

Thirty-nine skin biopsies from CTCL patients and 24 biopsies from healthy volunteers were taken. Immunohistochemical staining for STAT 3, 5a, 5b, and 6 was performed in formalin-fixed paraffin-embedded sections of mycosis fungoides (MF) and Sezary syndrome (SS) specimens.

RESULTS

We found increased expression of STAT proteins in CTCL: MF and SS skin in comparison to the control group. STAT5 but also STAT6 and to a lesser extent STAT3 seems to be constitutively activated in MF and SS. Moreover, also downregulation of STAT5b protein in advanced-stage CTCL appears to contribute to its pathogenesis. There were no significant associations between expression of STATs and pruritus severity.

CONCLUSIONS

Our results confirm the possible pathogenetic role of STATs in CTCL. STATs seem to be a promising target for new effective therapeutic agents in CTCL.