Multiplex spatial analysis reveals increased CD137 expression and m-MDSC neighboring tumor cells in refractory classical Hodgkin Lymphoma.

The Hodgkin and Reed - Sternberg (HRS) cells in classical Hodgkin Lymphoma (cHL) actively modify the immune tumor microenvironment (TME) attracting immunosuppressive cells and expressing inhibitory molecules. A high frequency of myeloid cells in the TME is correlated with an unfavorable prognosis, but more specific and rare cell populations lack precise markers. Myeloid-derived suppressor cells (MDSCs) have been identified in the peripheral blood of cHL patients, where they appear to be correlated with disease aggressiveness. TNFRSF9 (CD137) is a T cell co-stimulator expressed by monocytic and dendritic cells. Its expression has also been described in HRS cells, where it is thought to play a role in reducing antitumor responses. Here, we perform qualitative and quantitative analyses of lymphocytic and MDSC subtypes and determine the CD137 cell distribution in cHL primary tumors using multiplex immunofluorescence and automated multispectral imaging. The results were correlated with patients' clinical features. Cells were stained with specific panels of immune checkpoint markers (PD-1, PD-L1, CD137), tumor-infiltrating T lymphocytes (CD3, PD-1), and monocytic cells/MDSCs (CD68, CD14, CD33, Arg-1, CD11b). This approach allowed us to identify distinct phenotypes and to analyze spatial interactions between immune subpopulations and tumor cells. The results confirm CD137 expression by T, monocytic and HRS cells. In addition, the expression of CD137, T exhausted cells, and monocytic MDSCs (m-MDSCs) in the vicinity of malignant HRS cells were associated with a worse prognosis. Our findings reveal new elements of the TME that mediate immune escape, and confirm CD137 as a candidate target for immunotherapy in cHL.

CD137-expressing immune cells and HRS cells are more abundant and in closer proximity in refractory patients than in responders.Monocytic myeloid-derived suppressor cells (m-MDSCs) are associated with unfavorable outcomes and relapse in cHL, unlike granulocytic MDSCs (g-MDSCs), which are located far from HRS cells in non-responders.The cHL tumor microenvironment promotes immune escape in refractory patients by holistically driving polarization and/or recruitment of several cell types with increased expression of CD137 and PD-L1 checkpoints.

[Clinicopathological features of primary mucosal CD30-positive T-cell lymphoproliferative disorders].

Objective: To investigate the clinicopathological features and differential diagnosis of primary mucosal CD30-positive T-cell lymphoproliferative disorders (pmCD30+TLPD). Methods: Eight cases of pmCD30+TLPD diagnosed from 2013 to 2023 at the Department of Pathology, Beijing Friendship Hospital Affiliated to Capital Medical University and Beijing Ludaopei Hospital were retrospectively collected. The immunophenotype, EBV infection status and T-cell receptor (TCR) clonability of tumor cells were examined. The clinicopathological features were analyzed and related literatures were reviewed. Results: There were 5 females and 3 males, aged 28 to 73 years, without B symptoms, lack of trauma and autoimmune diseases. Seven cases occurred in oral mucosa and one in anal canal mucosa. Submucosal nodules with ulcerations were presented in all cases except one, which only submucosal nodule. Morphologically, there was different distribution of allotypic lymphocytes in inflammatory background. Four cases showed "kidney-shaped", "embryonic" and "horseshoe-shaped" cells, and one case resembled Hodgkin and Reed/Sternberg (HRS) cells. Allotypic lymphocytes expressed CD3 (7/8), CD4+/CD8-(7/8) and CD4-/CD8-(1/8). CD30 was uniformly strongly positive while ALK and CD56 were negative. In situ hybridization of EBER was negative in five cases (5/5). Clonal TCR gene rearrangement was positive in two cases. Four patients did not receive radiotherapy or chemotherapy. All the seven patients survived without disease except one died due to concurrent leukopenia. Conclusions: pmCD30+TLPD had a broad morphological spectrum and could be easily confused with primary cutaneous CD30+TLPD and systemic ALK-negative anaplastic large cell lymphoma involving mucosa, which may lead to misdiagnosis. Although the majority of the cases had a favorable prognosis, a few cases relapsed or progressed to lymphoma.

Multiplexed Spatial Profiling of Hodgkin Reed-Sternberg Cell Neighborhoods in Classic Hodgkin Lymphoma.

PURPOSE: Classic Hodgkin lymphoma (cHL) is a B-cell lymphoma that occurs primarily in young adults and, less frequently, in elderly individuals. A hallmark of cHL is the exceptional scarcity (1%-5%) of the malignant Hodgkin Reed-Sternberg (HRS) cells within a network of nonmalignant immune cells. Molecular determinants governing the relationship between HRS cells and their proximal microenvironment remain largely unknown. EXPERIMENTAL DESIGN: We performed spatially resolved multiplexed protein imaging and transcriptomic sequencing to characterize HRS cell states, cellular neighborhoods, and gene expression signatures of 23.6 million cells from 36 newly diagnosed Epstein-Barr virus (EBV)-positive and EBV-negative cHL tumors. RESULTS: We show that MHC-I expression on HRS cells is associated with immune-inflamed neighborhoods containing CD8+ T cells, MHC-II+ macrophages, and immune checkpoint expression (i.e., PD1 and VISTA). We identified spatial clustering of HRS cells, consistent with the syncytial variant of cHL, and its association with T-cell-excluded neighborhoods in a subset of EBV-negative tumors. Finally, a subset of both EBV-positive and EBV-negative tumors contained regulatory T-cell-high neighborhoods harboring HRS cells with augmented proliferative capacity. CONCLUSIONS: Our study links HRS cell properties with distinct immunophenotypes and potential immune escape mechanisms in cHL.

T-cell receptor gamma gene rearrangement analysis of classic Hodgkin lymphoma using a BIOMED-2 assay: a paraffin-embedded tissue analysis of one hundred cases.

In the new WHO classifications of haematolymphoid tumours (WHO-HAEM5), classic Hodgkin lymphoma (cHL) is categorized into B-cell lymphoid proliferations and lymphomas. Although the majority of Hodgkin Reed-Sternberg (HRS) cells are of germinal center B-cell origin with some defects of B-cell transcription factors, they rarely express T-cell antigens or cytotoxic molecules. Clonality analyses on cHL samples using BIOMED-2 have been reported by several groups; however, those studies were only focused on Ig regions, including IgH, Ig-kappa, and Ig-lambda, and TCR-γ clonality analysis of cHL has not yet been explored. Here, we investigated TCR-γ gene rearrangement for one hundred cases using a PCR-based method. Four of one hundred (4%) cases showed TCR-γ clonal peaks. Of these, three were at an advanced stage and one patient died of the disease. To clarify whether HRS cells showed T-cell clonality or not, we performed PCR analysis using DNAs of microdissected HRS cells. Three samples showed identical clonal peaks with bulk specimens. Our results indicate that cHL is a heterogeneous disease of mainly B-cell and rarely T-cell origin with a special phenotype. Further molecular studies are warranted.

Association between Epstein-Barr virus LMP-1 and Hodgkin lymphoma LMP-1 mechanisms in Hodgkin lymphoma development.

Hodgkin lymphoma is histologically characterised by the presence of Hodgkin (H) and Reed-Sternberg (RS) cells originating from germinal centre B-cells rearranged in the IgV gene. The formation of multinucleated RS cells is a product of telomere organisation in a process initiated by telomere aggregate accumulation in mononuclear H cells and may be mediated by latent membrane protein 1 (LMP-1) expression. LMP-1 is the main oncoprotein of EBV and supports several tumourigenic processes. LMP-1 may rescue proapoptotic B-cells through downregulation of B-cell receptor (BCR) components, mimicking and inducing multiple distinct B-cell signalling pathways to promote proliferation and survival, such as Janus kinase-signal transducer and activator of transcription (JAK-STAT), nuclear factor-kappa b (NF-кB), and cellular MYC (c-MYC), and inducing telomere instability mainly through Telomere repeat binding factor 2 (TRF2) downregulation to promote the formation of multinucleated RS cells. This review presents recent discoveries regarding the influence of LMP-1 on the surviving cellular signalling, genomic instability and mecanical formation of HRS cells.

Interfollicular Classic Hodgkin Lymphoma: Report of a Case and a Brief Review of Literature.

Interfollicular Hodgkin lymphoma (IHL) has been rarely reported in the literature and is recognized by the WHO Classification as a morphologic pattern sometimes seen in mixed cellularity classic Hodgkin lymphoma (CHL). The changes may be subtle due to preservation of architecture. We report a case of a 9-year-old male with IHL showing preserved follicular architecture but with the presence of interfollicular infiltrates consisting of eosinophils, plasma cells, and Hodgkin-Reed-Sternberg (HRS) cells. Immunophenotyping confirmed the morphologic suspicion for IHL. A discussion and review of the literature are offered. We conclude that IHL is a variant that requires a high index of suspicion, as it may be easily missed due to the subtle morphologic features and preserved architecture seen in most cases. We further emphasize that unexplained interfollicular infiltrates of eosinophils may be clues that should prompt a search of HRS cells and consideration of immunohistochemical staining if needed.

T-cell States, Repertoire, and Function in Classical Hodgkin Lymphoma Revealed through Single-Cell Analyses.

The classical Hodgkin lymphoma (cHL) environment is comprised of a dense and complex immune cell infiltrate interspersed with rare malignant Hodgkin-Reed-Sternberg (HRS) cells. HRS cells are actively surveilled by endogenous T cells, but data linking phenotypic and functional T-cell states with clonality at the single-cell level in cHL is lacking. To address this knowledge gap, we performed paired single-cell RNA and T-cell receptor sequencing on 14 cHL and 5 reactive lymphoid tissue specimens. Conventional CD4+ T cells dominated the cHL landscape. However, recurrent clonal expansion within effector and exhausted CD8+ T-cell and regulatory T-cell clusters was uniquely observed in cHL specimens. Multiplex flow cytometric analysis revealed that most lymphoma-resident T cells produced effector cytokines upon ex vivo restimulation, arguing against a profound dysfunctional T-cell state in cHL. Our results raise new questions about the nature of T cells that mediate the antilymphoma response following programmed cell death protein 1 (PD-1) blockade therapy in cHL.

Liquid biopsy: A promising tool for driving strategies and predicting failures in patients with classic Hodgkin lymphoma.

Classic Hodgkin lymphoma (cHL) consists of a heterogeneous group of haematological disorders that covers undifferentiated B cell neoplasms originating from germinal centre B cells. The HL molecular characterization still represents an ongoing challenge due to the low fraction of tumour Hodgkin and Reed-Sternberg cells mixed with a plethora of non-tumour haematological cells. In this scenario, next generation sequencing of liquid biopsy samples is emerging as a useful tool in HL patients' management. In this review, we aimed to overview the clinical and methodological topics regarding the implementation of molecular analysis in cHL, focusing on the role of liquid biopsy in diagnosis, follow-up, and response prediction.

Hodgkin Lymphoma: A disease shaped by the tumor micro- and macroenvironment.

The tumor microenvironment (TMicroE) and tumor macroenvironment (TMacroE) are defining features of classical Hodgkin lymphoma (cHL). They are of critical importance to clinicians since they explain the common signs and symptoms, allow us to classify these neoplasms, develop prognostic and predictive biomarkers, bioimaging and novel treatments. The TMicroE is defined by effects of cancer cells to their immediate surrounding and within the tumor. Effects of cancer cells at a distance or outside of the tumor define the TMacroE. Paraneoplastic syndromes are signs and symptoms due to effects of cancer at a distance or the TMacroE, which are not due to direct cancer cell infiltration. The most common paraneoplastic symptoms are B-symptoms, which manifest as fevers, chills, drenching night sweats, and/or weight loss. Less common paraneoplastic syndromes include those that affect the central nervous system, skin, kidney, and hematological autoimmune phenomena including hemophagocytic lymphohistiocytosis (HLH). Paraneoplastic signs such as leukocytosis, lymphopenia, anemia, and hypoalbuminemia are prognostic biomarkers. The neoplastic cells in cHL are the Hodgkin and Reed Sternberg (HRS) cells, which are preapoptotic germinal center B cells with a high mutational burden and almost universal genetic alterations at the 9p24.1 locus primarily through copy gain and amplification with strong activation of signaling via PD-L1, JAK-STAT, NFkB, and c-MYC. In the majority of cases of cHL over 95% of the tumor cells are non-neoplastic. In the TMicroE, HRS cells recruit and mold non-neoplastic cells vigorously via extracellular vesicles, chemokines, cytokines and growth factors such as CCL5, CCL17, IL6, and TGF-ß to promote a feed-forward inflammatory loop, which drives cancer aggressiveness and anti-cancer immune evasion. Novel single cell profiling techniques provide critical information on the role in cHL of monocytes-macrophages, neutrophils, T helper, Tregs, cytotoxic CD8+ T cells, eosinophils, mast cells and fibroblasts. Here, we summarize the effects of EBV on the TMicroE and TMacroE. In addition, how the metabolism of the TMicroE of cHL affects bioimaging and contributes to cancer aggressiveness is reviewed. Finally, we discuss how the TMicroE is being leveraged for risk adapted treatment strategies based on bioimaging results and novel immune therapies. In sum, it is clear that we cannot effectively manage patients with cHL without understanding the TMicroE and TMacroE and its clinical importance is expected to continue to grow rapidly.

[Progressively transformed germinal center-like follicular T-cell lymphoma:a clinicopathological analysis of 14 cases].

Objective: To investigate the clinicopathologic features of progressively transformed germinal center-like follicular T-cell lymphoma (PTGC-like FTCL). Methods: The clinicopathologic data of 14 PTGC-like FTCL cases that were diagnosed at the Beijing Friendship Hospital Affiliated to the Capital Medical University from January 2017 to January 2022 were retrospectively collected. Clinicopathological features, immunophenotype, and Epstein-Barr virus (EBV) infection status were analyzed in these cases. Polymerase chain reaction (PCR) was performed to detect the clonal gene rearrangements of T cell receptor (TCR) and the immunoglobulin (Ig) in 10 and 8 cases, respectively. Results: The male to female ratio was 5∶2. The median age was 61 years (range 32-70 years). All patients had lymphadenopathy at the time of diagnosis. By using the Ann Arbor system staging, seven cases were classified as stage Ⅰ-Ⅱ, and seven cases as stage Ⅲ-Ⅳ. Seven cases had B symptoms, four cases had splenomegaly, and two cases had skin rash and pruritus. Previously, three cases were diagnosed as classic Hodgkin's lymphoma, three cases as small B-cell lymphoma, two cases as atypical lymphoid hyperplasia unable to exclude angioimmunoblastic T-cell lymphoma (AITL), one case as EBV-associated lymphoproliferative disorder, and one case as peripheral T-cell lymphoma (PTCL) associated with the proliferation of B cells. All the 14 cases showed that the large nodules were composed of mature CD20+, IgD+B lymphocytes admixed with small aggregates of neoplastic cells with pale to clear cytoplasm. Moreover, hyperplastic germinal centers (GCs) and Hodgkin/Reed-Sternberg-like (HRS-like) cells were seen within these nodules in two and five cases, respectively. The neoplastic cells expressed CD3 (14/14), CD4 (14/14), PD1 (14/14), ICOS (14/14), CD10 (9/14), bcl-6 (12/14), CXCL13 (10/14), and CD30 (10/14). The HRS-like cells in five cases expressed CD20 (2/5), PAX5 (5/5), CD30 (5/5), CD15 (2/5), LCA (0/5), OCT2 (5/5) and BOB1 (2/5). Moreover, neoplastic T cells formed rosettes around HRS-like cells. EBV-encoded RNA (EBER) in situ hybridization showed scattered, small, positive bystander B lymphocytes in 8/14 cases, including 3/5 cases containing HRS-like cells. All tested cases (including five with HRS-like cells) showed monoclonal TCR gene rearrangement and polyclonal Ig gene rearrangement. Conclusions: PTGC-like FTCL is a rare tumor originated from T-follicular helper cells. It could be distinguished from angioimmunoblastic T-cell lymphoma by the formation of follicular structure, and lack of follicular dendritic cell proliferation outside the follicles and the polymorphous inflammatory background. In addition, it should be differentiated from lymphocyte-rich classical Hodgkin's lymphoma and low-grade B cell lymphoma.

Exophthalmos and ocular pain as clinical debut of intracranial Hodgkin's lymphoma at diagnosis.

Intracranial involvement in Hodgkin's Lymphoma (HL) is extremely unusual, especially at the time of diagnosis. Because of its non-specific radiological behaviour, it can be confused with more common entities with a radically different prognosis. Pathologically, large and bi-nucleated cells, called Reed-Sternberg cells, embedded in an inflammatory network. In this report we describe the clinical case of a patient, with no medical history, with left ocular pain and exophthalmos as presetation of intracranial HL at diagnosis and review the most current literature. Intracranial involvement is often associated with extracranial disease. Therefore, a systemic study including body computed tomography, bone marrow biopsy and ophthalmological evaluation is necessary. Intracranial lesions respond favourably to treatment and the prognosis depends on the extracranial involvement. To date, there is no standardised management scheme for these patients. For us, the primary role of surgery in this context is to perform a biopsy to confirm the histological diagnosis.

Classic Hodgkin lymphoma in young people.

Classic Hodgkin lymphoma (CHL) is a unique form of lymphoid cancer featuring a heterogeneous tumor microenvironment and a relative paucity of malignant Hodgkin and Reed-Sternberg (HRS) cells with characteristic phenotype. Younger individuals (children, adolescents and young adults) are affected as often as the elderly, producing a peculiar bimodal age-incidence profile that has generated immense interest in this disease and its origins. Decades of epidemiological investigations have documented the populations most susceptible and identified multiple risk factors that can be broadly categorized as either biological or environmental in nature. Most risk factors result in overt immunodeficiency or confer more subtle alterations to baseline health, physiology or immune function. Epstein Barr virus, however, is both a risk factor and well-established driver of lymphomagenesis in a significant subset of cases. Epigenetic changes, along with the accumulation of somatic driver mutations and cytogenetic abnormalities are required for the malignant transformation of germinal center-experienced HRS cell precursors. Chromosomal instability and the influence of endogenous mutational processes are critical in this regard, by impacting genes involved in key signaling pathways that promote the survival and proliferation of HRS cells and their escape from immune destruction. Here we review the principal features, known risk factors and lymphomagenic mechanisms relevant to newly diagnosed CHL, with an emphasis on those most applicable to young people.

[The history of Hodgkin lymphoma]. / Historique du lymphome de Hodgkin.

THE HISTORY OF HODGKIN LYMPHOMA. Hodgkin lymphoma was initially considered to be caused by infectious agents. The Hodgkin and Reed-Sternberg tumor cells are derived from mature B cells and transforming events were identified. Staging laparotomy has been discontinued for clinical evaluation with the progress of medical imaging. For seven decades, clinical trials have allowed to define risk factors, to improve standard treatments with the optimal use of chemotherapy and radiotherapy. A risk adapted strategy and early response to chemotherapy are mandatory to reduce long-term consequences of treatment.

HISTORIQUE DU LYMPHOME DE HODGKIN. Une origine infectieuse du lymphome de Hodgkin a été initialement suspectée. L'origine des cellules tumorales, les mécanismes oncogéniques permettant leur survie et leur prolifération sont de connaissance plus récente. Après l'abandon de la laparotomie exploratrice, les progrès de l'imagerie médicale ont été continus. Pendant sept décennies, les essais cliniques ont permis de définir les facteurs de risque, d'améliorer les traitements de référence avec une utilisation optimale de la chimiothérapie et de la radiothérapie. La stratégie adaptée au risque et à la réponse précoce à la chimiothérapie est nécessaire pour limiter les conséquences tardives des traitements.

BET inhibitors induce NF-κB and E2F downregulation in Hodgkin and Reed-Sternberg cells.

The prognosis of patients with relapsed and/or refractory classic Hodgkin lymphoma (cHL) continues to be poor. Therefore, there is a continuing need to develop novel therapies and to rationalize the use of target combinations. In recent years there has been growing interest in epigenetic targets for hematological malignancies under the rationale of the presence of common alterations in epigenetic transcriptional regulation. Since Hodgkin and Reed-Sternberg (HRS) cells have frequent inactivating mutations of the CREBBP and EP300 acetyltransferases, bromodomain and extra-terminal (BET) inhibitors can be a rational therapy for cHL. Here we aimed to confirm the efficacy of BET inhibitors (iBETs) using representative cell models and functional experiments, and to further explore biological mechanisms under iBET treatment using whole-transcriptome analyses. Our results reveal cytostatic rather than cytotoxic activity through the induction of G1/S and G2/M cell-cycle arrest, in addition to variable MYC downregulation. Additionally, massive changes in the transcriptome induced by the treatment include downregulation of relevant pathways in cHL disease: NF-kB and E2F, among others. Our findings support the therapeutic use of iBETs in selected cHL patients and reveal previously unknown biological mechanisms and consequences of pan-BET inhibition.

The Polyvalent Role of CD30 for Cancer Diagnosis and Treatment.

CD30, also known as TNFRSF8 (tumor necrosis factor receptor superfamily member 8), is a protein receptor that is heavily glycosylated inside the Golgi apparatus, as well as a tumor marker that is found on the surface of specific cells in the body, including certain immune cells and cancer ones. This review aims to shed light on the critical importance of CD30, from its emergence in the cell to its position in diagnosing various diseases, including Hodgkin lymphoma, where it is expressed on Hodgkin and Reed-Sternberg cells, as well as embryonal carcinoma, anaplastic large cell lymphoma (ALCL), and cutaneous T-cell lymphoma (CTCL). In addition to its role in positive diagnosis, targeting CD30 has been a promising approach treating CD30-positive lymphomas, and there is ongoing research into the potential use of CD30-targeted therapies for autoimmune disorders. We aim to elaborate on CD30's roles as a tumor marker, supporting thus the hypothesis that this receptor might be the aim of cytostatic treatment.

New molecular targets in Hodgkin and Reed-Sternberg cells.

Recent discoveries shed light on molecular mechanisms responsible for classical Hodgkin lymphoma (HL) development and progression, along with features of Hodgkin - Reed and Sternberg cells (HRS). Here, we summarize current knowledge on characteristic molecular alterations in HL, as well as existing targeted therapies and potential novel treatments for this disease. We discuss the importance of cluster of differentiation molecule 30 (CD30) and the programmed cell death-1 protein (PD-1) and ligands (PD-L1/2), and other molecules involved in immune modulation in HL. We highlight emerging evidence indicating that the altered function of SWI/SNF-type chromatin remodeling complexes, PRC2, and other epigenetic modifiers, contribute to variations in chromatin status, which are typical for HL. We postulate that despite of the existence of plentiful molecular data, the understanding of HL development remains incomplete. We therefore propose research directions involving analysis of reverse signaling in the PD-1/PD-L1 mechanism, chromatin remodeling, and epigenetics-related alterations, in order to identify HL features at the molecular level. Such attempts may lead to the identification of new molecular targets, and thus will likely substantially contribute to the future development of more effective targeted therapies.

CD30 induces Reed-Sternberg cell-like morphology and chromosomal instability in classic Hodgkin lymphoma cell lines.

Classic Hodgkin lymphoma (cHL) is characterized by multinucleated cells called Reed-Sternberg (RS) cells and genetic complexity. Although CD30 also characterizes cHL cells, its biological roles are not fully understood. In this report, we examined the link between CD30 and these characteristics of cHL cells. CD30 stimulation increased multinucleated cells resembling RS cells. We found chromatin bridges, a cause of mitotic errors, among the nuclei of multinucleated cells. CD30 stimulation induced DNA double-strand breaks (DSBs) and chromosomal imbalances. RNA sequencing showed significant changes in the gene expression by CD30 stimulation. We found that CD30 stimulation increased intracellular reactive oxygen species (ROS), which induced DSBs and multinucleated cells with chromatin bridges. The PI3K pathway was responsible for CD30-mediated generation of multinucleated cells by ROS. These results suggest that CD30 involves generation of RS cell-like multinucleated cells and chromosomal instability through induction of DSBs by ROS, which subsequently induces chromatin bridges and mitotic error. The results link CD30 not only to the morphological features of cHL cells, but also to the genetic complexity, both of which are characteristic of cHL cells.

Increased STAT expression in Reed-Sternberg cells as a potential positive prognostication biomarker in Hodgkin lymphoma.

Classic Hodgkin lymphoma (cHL) prognostication primarily relies on clinical and radiological factors. Despite this, a subset of patients still progress. Immunohistochemistry (IHC) based biomarkers on diagnostic tissue have not been routinely used for prognostication. A multicentre retrospective analysis identified 62 patients with cHL. IHC on diagnostic tissues was used to stain Reed-Sternberg cells (RS) cells for STAT1, pSTAT3, p53 and tumour microenvironment for CD68 and PD-1. IHC stains were scored by anatomical pathologists blinded to patients and their outcomes and correlated with survival. Strong intensity of STAT1 and pSTAT3 staining correlated with improved overall survival (OS), with hazard ratios (HR) of 0.21 [95% confidence interval (CI) 0.06-0.76] and 0.22 (95% CI 0.06-0.84), respectively. Similarly, the median OS for weak versus strong STAT1 or pSTAT3 staining was 8.8 years versus not reached. Other IHC stains did not correlate with prognosis. In this cohort of cHL patients, downregulation of immunohistochemical STAT1 or pSTAT3 in RS cells is associated with inferior OS, suggesting STAT transcription within the pathognomonic RS cells may have tumour suppressor function and may be a potential biomarker for cHL prognosis.

Diagnostic Utility of STAT6 and pSTAT6 Immunohistochemistry for Distinguishing Classic Hodgkin Lymphoma and Peripheral T-Cell Lymphoma With Hodgkin and Reed-Sternberg-like Cells.

Peripheral T-cell lymphomas (PTCLs), particularly nodal lymphomas of T-follicular helper cell origin, may include Hodgkin/Reed-Sternberg (HRS)-like cells in their microenvironment. These HRS-like cells are morphologically indistinguishable from HRS cells of classic Hodgkin lymphoma (CHL). Therefore, PTCLs with HRS-like cells pose a differential diagnosis vis-à-vis CHL. A previous study reported that, in contrast to HRS cells, programmed death-ligand 1 (PD-L1) expression is rare in HRS-like cells of PTCLs and suggested that PD-L1 immunohistochemistry is useful to differentiate HRS cells and HRS-like cells. In this study, we analyzed 21 patients with PTCL with HRS-like cells and 34 patients with CHL and assessed the diagnostic utility of STAT6, pSTAT6, and pSTAT3 immunohistochemistry in distinguishing HRS cells from HRS-like cells. In addition, we also performed PD-L1 immunohistochemistry to reconfirm its utility in distinguishing the 2 diseases. Compared with HRS cells in CHLs, HRS-like cells in PTCLs showed significantly less positivity for STAT6 (9.6% vs. 70%, P <0.001), pSTAT6 (9.6% vs. 70%, P <0.001), and PD-L1 (9.6% vs. 85%, P <0.001). Thus, we reconfirmed the diagnostic utility of PD-L1 immunohistochemistry in distinguishing CHLs from PTCLs with HRS-like cells. In contrast, both HRS-like and HRS cells were highly associated with pSTAT3 expression, with no significant difference in positive cell frequency (86% vs. 91%, P =0.66). On the basis of these findings, we conclude that, in addition to PD-L1, STAT6 and pSTAT6 immunohistochemistry are helpful diagnostic tools to distinguish CHLs from PTCLs with HRS-like cells.