Molecular features of non-anaplastic peripheral T-cell lymphoma in children and adolescents

Hepatosplenic T-cell lymphoma in children and adolescents

ABSTRACT

Hepatosplenic T-cell lymphoma (HSTCL) is an aggressive mature T-cell lymphoma characterized by significant hepatosplenomegaly, bone marrow involvement, and minimal or no lymphadenopathy. Primarily affecting young adults, it is exceptionally rare in children and adolescents. This makes diagnosis and treatment particularly challenging for pathologists and pediatric oncologists. Diagnosis typically relies on bone marrow, spleen, or liver biopsy, with histopathologic features including small/medium lymphoid cells with irregular nuclear contours that obstruct the sinuses or sinusoids of the spleen or liver. Immunophenotyping usually reveals CD2/3/7 positivity and CD4/8 negativity, with γδ T-cell receptor rearrangements in most cases. Some genetic distinctions described in pediatric and adolescent patients include chromosome 7 and 8 abnormalities and mutations involving SETD2 and STAT5B. Given the lack of standardized approaches, childhood and adolescent patients with HSTCL are often treated with adult protocols, such as intensive cytotoxic chemotherapy regimens followed by allogeneic hematopoietic stem cell transplantation. Despite these highly intensive treatments, the prognosis for HSTCL remains poor in children and adolescents, with an estimated 5-year overall survival of <15%. HSTCL's rarity in children and adolescents limits accurate epidemiological estimates, clinical experience, data collection, treatment advances, and surveillance recommendations. Data on relapsed/refractory disease are even more limited. This review summarizes known clinical and histopathologic features as well as outcomes specific to children and adolescents with HSTCL, highlighting potential distinctions from adults. We will also discuss future strategies to acquire additional biologic and molecular data, streamline diagnosis, and advance treatment approaches to ultimately improve outcomes for young patients with this deadly disease.

Peripheral T-cell lymphoma-NOS in children and adolescents: a review from the Children's Oncology Group NHL Committee

ABSTRACT

Peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) is a rare mature T-cell non-Hodgkin lymphoma (NHL) seen in both children and adults. Although it is the most common nonanaplastic mature T-cell lymphoma of childhood, it is quite rare and, therefore, the standard of care remains largely undefined. It is a disease characterized by clinical and pathological heterogeneity and is generally associated with an aggressive clinical course and poor prognosis in adults. Retrospective reports on treatment outcomes for pediatric PTCL-NOS are limited by small cohorts, variable clinical presentations, and heterogeneous treatment regimens. Although published survival rates in children appear encouraging compared with those from prospective studies in adults, the prognosis is guarded, and relatively low curative outcomes are in stark contrast to more common pediatric NHL. Although recent landmark gene profiling studies have shed light on the molecular landscape of the disease in adults, identifying molecular subgroups with prognostic significance, the biology of PTCL-NOS remains unclear in children. Here, we review the clinical presentation and diagnosis, historical treatment approaches, current knowledge of the disease biology, and the role of hematopoietic stem cell transplant (HSCT) in PTCL-NOS in children to pursue a better understanding of this heterogeneous condition and empower physicians to use this information to best support our pediatric population. Studies focusing on pediatric PTCL-NOS are required to unravel the disease biology in children, improve risk stratification, and better define upfront treatment through the role of targeted agents and HSCT, as we look to future directions of the care of children with PTCL-NOS.

Pediatric lymphomas: overview and diagnostic challenges

Only 10% of new lymphoma diagnoses in the USA occur in children < 15 years. Although the same diagnostic criteria apply to both adult and pediatric lymphomas, there are important differences in some lymphoma subtypes. These differences are recognized by the World Health Organization (WHO) with the recent 2022 classification of pediatric tumors including pediatric hematopoietic tumors. Here, we review the WHO classification scheme for pediatric lymphomas and summarize the diagnostic criteria, recent genetic findings, and differences from their adult counterparts for some subtypes including those yet to be included as a definitive subtype. In general, there are differences in relatively frequency, genetic mutation, and prognosis with the pediatric counterpart often having better prognosis. Emerging B-cell lymphomas with recurrent gene alterations such as IRF4 rearrangement and 11q gain/loss chromosomal alterations will be reviewed. The overlapping pathological, clinical, and molecular features between pediatric-type follicular lymphoma (PTFL) and pediatric nodal marginal zone lymphoma (PNMZL) suggesting one disease with broad morphological spectrum will be discussed. The pathogenetic role of EBV in subclassifying Burkitt lymphoma is highlighted. The revised classification of the EBV-positive lymphoproliferative disorders in children is discussed. This review will focus on novel findings, areas of special interest, and diagnostic challenges in pediatric lymphomas.

Lack of SMARCB1 expression characterizes a subset of human and murine peripheral T-cell lymphomas

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous group of malignancies with poor outcome. Here, we identify a subgroup, PTCL-NOSSMARCB1-, which is characterized by the lack of the SMARCB1 protein and occurs more frequently in young patients. Human and murine PTCL-NOSSMARCB1- show similar DNA methylation profiles, with hypermethylation of T-cell-related genes and hypomethylation of genes involved in myeloid development. Single-cell analyses of human and murine tumors revealed a rich and complex network of interactions between tumor cells and an immunosuppressive and exhausted tumor microenvironment (TME). In a drug screen, we identified histone deacetylase inhibitors (HDACi) as a class of drugs effective against PTCL-NOSSmarcb1-. In vivo treatment of mouse tumors with SAHA, a pan-HDACi, triggered remodeling of the TME, promoting replenishment of lymphoid compartments and reversal of the exhaustion phenotype. These results provide a rationale for further exploration of HDACi combination therapies targeting PTCL-NOSSMARCB1- within the TME.

Hematopoietic stem cell transplantation for pediatric patients with non-anaplastic peripheral T-cell lymphoma. An EBMT pediatric diseases working party study

Peripheral T-cell lymphomas (PTCL) other than anaplastic large-cell lymphoma are rare in children, and the role of hematopoietic stem cell transplantation (HSCT) has not been clarified yet. In a retrospective analysis of registry-data of the European Society for Blood and Marrow Transplantation we analyzed 55 patients aged < 18 years who received allogeneic (N = 46) or autologous (N = 9) HSCT for PTCL. Median age at HSCT was 13.9 years; 33 patients (60%) were in first remission, and 6 (19%) in progression at HSCT. Conditioning was myeloablative in 87% of the allogeneic HSCTs and in 27 (58.7%) based on total body irradiation. After allogeneic HSCT the 5-year overall- and progression-free survival was 58.9% (95% CI 42.7-71.9) and 52.6% (95% CI 36.8-66.1), respectively. 5-year relapse incidence was 27.6% (95% CI 15.1-41.6), the non-relapse mortality rate was 19.8% (95% CI 9.7-32.6). Five of the six patients with progression at HSCT died. Seven of nine patients after autologous HSCT were alive and disease-free at last follow-up. Our data suggest a role of allogeneic HSCT in consolidation-treatment of patients with high-risk disease, who reach at least partial remission after primary- or relapse-therapy, whereas patients with therapy-refractory or progressive disease prior to transplantation do not profit from HSCT.

SARS-CoV-2 infection activates inflammatory macrophages in vascular immune organoids

SARS-CoV-2 provokes devastating tissue damage by cytokine release syndrome and leads to multi-organ failure. Modeling the process of immune cell activation and subsequent tissue damage is a significant task. Organoids from human tissues advanced our understanding of SARS-CoV-2 infection mechanisms though, they are missing crucial components: immune cells and endothelial cells. This study aims to generate organoids with these components. We established vascular immune organoids from human pluripotent stem cells and examined the effect of SARS-CoV-2 infection. We demonstrated that infections activated inflammatory macrophages. Notably, the upregulation of interferon signaling supports macrophages' role in cytokine release syndrome. We propose vascular immune organoids are a useful platform to model and discover factors that ameliorate SARS-CoV-2-mediated cytokine release syndrome.

CD27/CD70 pathway activation in primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder

Primary cutaneous CD4+ small or medium T-cell lymphoproliferative disorder (PCSM-LPD) is a clonal T-cell proliferation disease confined to the skin. PCSM-LPD shares expression of T follicular helper (Tfh) cell markers with various mature T-cell lymphomas. However, the benign presentation of PCSM-LPD contrasts the clinical behavior of other Tfh-lymphomas. The aim of our study was to delineate the molecular similarities and differences between PCSM-LPD and other Tfh-derived lymphomas to explain the clinical behavior and unravel possible pathological mechanisms. We performed targeted next-generation sequencing of 19 genes recurrently mutated in T-cell neoplasms in n = 17 PCSM-LPD with high and in n = 21 PCSM-LPD with low tumor cell content. Furthermore, gene expression profiling was used to identify genes potentially expressed in the PD1-positive (PD1+) neoplastic cells. Expression of some of these genes was confirmed in situ using multistain immunofluorescence. We found that PCSM-LPD rarely harbored mutations recurrently detected in other T-cell neoplasms. PCSM-LPD is characterized by the invariable expression of the T-cell-receptor-associated LCK protein. CD70 and its ligand CD27 are co-expressed on PD1+ PCSM-LPD cells, suggestive of autoactivation of the CD70 pathway. In conclusion, PCSM-LPD differs from disseminated lymphomas of Tfh origin by their mutation profile. Activation of CD70 signaling also found in cutaneous T-cell lymphoma represents a potential driver of neoplastic proliferation of this benign neoplasia of Tfh. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Biopathology of childhood, adolescent and young adult non-Hodgkin lymphoma

Mature non-Hodgkin lymphomas (NHL) in the childhood, adolescent and young adult (CAYA) population are rare and exhibit unique clinical, immunophenotypic and genetic characteristics. Application of large-scale unbiased genomic and proteomic technologies such as gene expression profiling and next generation sequencing (NGS) have led to enhanced understanding of the genetic basis for many lymphomas in adults. However, studies to investigate the pathogenetic events in CAYA population are relatively sparse. Enhanced understanding of the pathobiologic mechanisms involved in non-Hodgkin lymphomas in this unique population will allow for improved recognition of these rare lymphomas. Elucidation of the pathobiologic differences between CAYA and adult lymphomas will also lead to the design of more rational and much needed, less toxic therapies for this population. In this review, we summarize recent insights gained from the proceedings of the recent 7th International CAYA NHL Symposium held in New York City, New York October 20-23, 2022.

Diagnosis and management of rare paediatric Non-Hodgkin lymphoma

Mature B-cell lymphomas, (B- or T-cell) lymphoblastic lymphomas (LBL), and anaplastic large cell lymphoma (ALCL) correspond to about 90% of all non-Hodgkin lymphoma (NHL) cases occurring in children and adolescents. The remaining 10% encompass a complex group of entities characterized by low/very low incidences, paucity of knowledge in terms of underlying biology in comparison to their adult counterparts, and consequent lack of standardization of care, information on clinical therapeutic efficacy and long-term survival. At the Seventh International Symposium on Childhood, Adolescent and Young Adult NHL, organized on October 20-23, 2022, in New York City, New York, US, we had the opportunity to discuss clinical, pathogenetic, diagnostic, and treatment aspects of certain subtypes of rare B- or T-cell NHL and they will be the topic of this review.

Diagnosis and management of cutaneous lymphomas and lymphoid proliferations in children, adolescents and young adults (CAYA)

Cutaneous lymphomas and lymphoid proliferations (LPD) in children, adolescents, and young adults (CAYA) are a heterogeneous group of lymphoid neoplasms that present formidable diagnostic challenges to clinicians and pathologists alike. Although rare overall, cutaneous lymphomas/LPD occur in real-world settings and awareness of the differential diagnosis, potential complications, and various therapeutic approaches will help ensure the optimal diagnostic work-up and clinical management. Lymphomas/LPD involving the skin can occur as primary cutaneous disease in a patient that characteristically has lymphoma/LPD confined to the skin, or as secondary involvement in patients with systemic disease. This review will comprehensively summarize both primary cutaneous lymphomas/LPD that occur in the CAYA population as well as those CAYA systemic lymphomas/LPD with propensity for secondary cutaneous involvement. Focus on the most common primary entities occurring in CAYA will include lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma, mycosis fungoides, subcutaneous panniculitis-like T-cell lymphoma, and hydroa vacciniforme lymphoproliferative disorder.

Epigenetic regulation in hematopoiesis and its implications in the targeted therapy of hematologic malignancies

Hematologic malignancies are one of the most common cancers, and the incidence has been rising in recent decades. The clinical and molecular features of hematologic malignancies are highly heterogenous, and some hematologic malignancies are incurable, challenging the treatment, and prognosis of the patients. However, hematopoiesis and oncogenesis of hematologic malignancies are profoundly affected by epigenetic regulation. Studies have found that methylation-related mutations, abnormal methylation profiles of DNA, and abnormal histone deacetylase expression are recurrent in leukemia and lymphoma. Furthermore, the hypomethylating agents and histone deacetylase inhibitors are effective to treat acute myeloid leukemia and T-cell lymphomas, indicating that epigenetic regulation is indispensable to hematologic oncogenesis. Epigenetic regulation mainly includes DNA modifications, histone modifications, and noncoding RNA-mediated targeting, and regulates various DNA-based processes. This review presents the role of writers, readers, and erasers of DNA methylation and histone methylation, and acetylation in hematologic malignancies. In addition, this review provides the influence of microRNAs and long noncoding RNAs on hematologic malignancies. Furthermore, the implication of epigenetic regulation in targeted treatment is discussed. This review comprehensively presents the change and function of each epigenetic regulator in normal and oncogenic hematopoiesis and provides innovative epigenetic-targeted treatment in clinical practice.