Peripheral T-cell lymphoma classification: the matter of cellular derivation

Maturation-related and functional-associated phenotypic profile of tumor T-cells in mature/peripheral T-cell neoplasms: association with the diagnostic subtype of the disease

T-cell chronic lymphoproliferative disorders (T-CLPD) are a heterogeneous group of mature T-cell malignancies, whose classification remains challenging. Here we classified tumor cells from 86 patients diagnosed with either T-CLPD (n=81) or T-acute lymphoblastic leukemia (n=5) into precise functional and maturation-associated compartments, based on their phenotypic similarities with their normal maturation-related and functional-associated T-cell counterparts. A database was generated using blood samples from 6 sex- and age-matched healthy donors as a template for normal T-cell subsets flow cytometric immunophenotypes, to which tumor cells of individual patients were compared. Except for nodal T-follicular helper (TFH) cell-lymphoma and adult T-cell leukemia/lymphoma (ATLL), which showed phenotypes overlapping with TFH and T regulatory cells, respectively, all other T-CLPD displayed immunophenotypic profiles consistent with conventional T-helper (h) cells, with different maturation-associated profiles per diagnostic category. These included predominant naive/naive-central memory phenotypes in T-prolymphocytic leukemia (T-PLL) to terminal effector cytotoxic cellular profiles in T-large granular lymphocytic leukemia (T-LGLL); other T-CLPD diagnostic categories (mostly Sézary syndrome/mycosis fungoides, SS/MF) resembled the diverse memory T-cell subsets. Interestingly, immunophenotypically less mature tumor cells (T-PLL) displayed more heterogeneous Th-profiles, while those with memory T-cell profiles showed more consistent Th-associated patterns (e.g., Th2 or Th17 in SS/MF), and the most mature neoplasms (e.g., T-LGLL) systematically displayed a Th1-like pattern, reflecting a progressively lower plasticity for the more advanced tumor-associated maturation stages. These findings confirm the presence of distinct phenotypic patterns resembling specific maturation-associated and Th-related profiles of normal T-cells among distinct diagnostic categories of T-CLPD, which might contribute to a more precise classification of T-CLPD.

A Comparison of the Fifth World Health Organization and the International Consensus Classifications of Mature T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are a rare subset of non-Hodgkin lymphomas that often carry significant difficulty in diagnosis and classification because of their rarity and biological complexity. Previous editions of the World Health Organization (WHO) classifications of hemopoietic neoplasms in 2001, 2008, and 2017 aimed to standardize hemopoietic neoplasm diagnosis in general. Since then, crucial clinico-pathological, immunophenotypic, and recent molecular discoveries have been made in the field of lymphomas, contributing to refining diagnostic criteria of several diseases, upgrading entities previously defined as provisional, and identifying new entities. In 2022, two different models were proposed to classify hematolymphoid neoplasms: the 5th edition of the WHO classification (WHO-HAEM5) and the International Consensus Classification (ICC). Of note, a common nosography is mandatory to ensure progress in health science and ensure the basis for a real precision medicine. In this article, the authors summarized the main differences with the previous fourth WHO edition and reviewed the main discrepancies between the two newest classifications, as far as PTCLs are concerned.

Incidence, Treatment, and Survival of Patients With T-Cell Lymphoma, T-Cell Large Granular Leukemia, and Concomitant Plasma Cell Dyscrasias

T-Cell malignancies are a group of heterogeneous disorders composed of primary cutaneous T-cell lymphomas (CTCLs), peripheral T-cell lymphomas (PTCLs), and T-cell leukemias, including T-cell large granular lymphocytic leukemia (T-LGLL). Cases of patients with combined T-cell malignancies and plasma cell dyscrasias (PCD) are reported in the literature, but these are mostly limited to case reports or small case series with <10 patients. Here, we described the clinical course of 26 patients and report baseline characteristics and clinical outcomes including overall survival (OS), progression-free survival (PFS), and objective response rates (ORRs) in this unique population. There was no survival difference in patients with CTCL or T-LGLL and concomitant PCD when treated with standard therapy directed at the T-cell malignancy when compared to historical controls. However, patients with PTCL and concomitant PCD had significantly inferior outcomes with rapid progression and worse OS and PFS at 1.7 years (p=0.006) and 4.8 months (p=0.08), respectively, when compared to historical controls for patients with PTCL, although the limited number of patients included in this analysis precludes drawing definitive conclusions. Treatment directed at the T-cell malignancy resulted in the eradication of the PCD clone in multiple patients (15.4%) including one with multiple myeloma (MM) who experienced a complete response after starting therapy directed at the T-cell malignancy. For patients with T-cell malignancies and concomitant PCD, treatment with standard T-cell-directed therapies is recommended based on this analysis with continued follow-up and monitoring of the concomitant PCD. Further studies are needed to definitively elucidate the increased risk of relapse in patients with PTCL and concomitant PCD, and larger, multi-center cohorts are needed to validate these findings across T-cell malignancies and PCDs.

Application of a 5 Marker Panel to the Routine Diagnosis of Peripheral T-Cell Lymphoma With T-Follicular Helper Phenotype

The 2017 World Health Organization update introduced a new category of nodal peripheral T-cell lymphoma with T-follicular helper phenotype (PTCL-TFH) defined by expression of at least 2 or 3 TFH markers. Our study assesses the utility of an immunohistochemical panel of 5 TFH markers (CD10, BCL6, PD-1, CXCL13, and ICOS) for identification of TFH phenotype in angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified (NOS). Immunohistochemical for the 5 markers was performed on 22 cases of AITL and 29 cases of PTCL-NOS. Cases were reviewed for morphologic features characteristic of AITL. All AITL cases showed expression of ≥2 TFH markers. This panel resulted in reclassification of 41% PTCL-NOS cases to PTCL-TFH. Positive percent agreement for the TFH phenotype is 97% for PD1, 94% for ICOS, 44% for CD10 and CXCL13, and 29% for BCL6. Negative percent agreement for TFH phenotype is 100% for CD10, BCL6, and CXCL13, 82% for ICOS and 71% for PD1. AITL cases were more likely than PTCL-TFH cases to contain expanded CD21-positive follicular dendritic cell meshworks, clear cell cytology and polymorphous inflammatory background; however, there was a significant (P<0.005) Kruskal-Wallis trend in all morphologic variables between the 3 groups suggesting a continuum from PTCL-NOS to PTCL-TFH to AITL. The median number of morphologic features of AITL also correlated significantly with number of TFH markers positive (Spearman coefficient ρ=0.759). In summary, the stain panel chosen will have an impact on cases classified as PTCL-TFH. This entity may exist along a spectrum between PTCL-NOS and AITL.

Immunophenotype evaluation of Non-Hodgkin's lymphomas

Background: Non-Hodgkin's lymphoma (NHLs) is known as a heterogeneous group of malignant lymphoproliferative disorders. NHLs are classified into B cell and T cell types. Immunophenotypical assessment of the biopsy specimens can help diagnose NHLs. Methods: In this study, 77 patients with B cell and T cell lymphoma were selected from Shahid Sadoghi hospital during 2010 to 2013. Immunohistochemical method was used to detect biomarkers like CD2, CD3, CD20, and CD45. Results: In this study, 67 patients (87.01 %) had B cell lymphoma. Moreover, the most primary tissues in B cell group were lymph node and stomach, followed by bone marrow and neck. Positive co-expression of CD45 and CD20 was found in 61 patients (91.04%) with B cell lymphoma. However, 10 patients (12.98%) had T cell lymphoma, and the most primary tissue in T cell lymphoma group was the skin. Moreover, CD3 expression was seen in all patients with T cell lymphoma. Conclusion: This study confirmed the main role of immunohistochemistry method in classifying and diagnosing NHLs. Moreover, the difference in CD marker expression and age in patients with B cell and T cell lymphoma, compared to other studies may be due to geographic area and genetic and ethnic differences.

The heterogeneous landscape of ALK negative ALCL

Anaplastic Large Cell Lymphoma (ALCL) is a clinical and biological heterogeneous disease including systemic ALK positive and ALK negative entities. Whereas ALK positive ALCLs are molecularly characterized and readily diagnosed, specific immunophenotypic or genetic features to define ALK negative ALCL are missing, and their distinction from other T-cell non-Hodgkin lymphomas (T-NHLs) can be controversial. In recent years, great advances have been made in dissecting the heterogeneity of ALK negative ALCLs and in providing new diagnostic and treatment options for these patients. A new revision of the World Health Organization (WHO) classification promoted ALK negative ALCL to a definite entity that includes cytogenetic subsets with prognostic implications. However, a further understanding of the genetic landscape of ALK negative ALCL is required to dictate more effective therapeutic strategies specifically tailored for each subgroup of patients.

Extranodal NK/T cell lymphoma and aggressive NK cell leukaemia: evidence for their origin on CD56+bright CD16-/+dim NK cells

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into extranodal NK/T cell lymphoma, nasal type (ENKTL) and aggressive NK cell leukaemia (ANKL). In order to propose their normal NK cell counterparts, we reviewed the literature on the phenotype of the neoplastic NK cells from five series of patients with ENKTL (n = 411) and seven series of patients with ANKL (n = 114) and compared with that of the normal and activated mature CD56 NK cell subsets. The tumour NK cells usually express brightly the CD56 adhesion molecule and CD94 lectin type killer receptor, and have an activation-related (cytoplasmic CD3ε, CD7, CD45RO, HLA-DR) phenotype; in contrast, CD16 and killer immunoglobulin-like receptors are frequently negative, and CD57 expression is almost never observed. These phenotypic features would suggest that ENKTL and ANKL cells do represent the neoplastic counterpart of the mature CD56 NK cells, which undergo activation and malignant transformation after Epstein-Barr virus infection.

The Comparative Diagnostic Features of Canine and Human Lymphoma

The non-Hodgkin lymphomas (NHLs) are a heterogeneous family of lymphoid malignancies that are among the most common neoplasms of both dogs and humans. Owing to shared molecular, signaling, incidence, and pathologic features, there is a strong framework supporting the utilization of canine lymphoma as a comparative, large animal model of human NHL. In alignment with the biologic similarities, the current approach towards the diagnosis and classification of canine lymphoma is based upon the human World Health Organization guidelines. While this approach has contributed to an increasing appreciation of the potential biological scope of canine lymphoma, it has also become apparent that the most appropriate diagnostic philosophy must be multimodal, namely by requiring knowledge of microscopic, immunophenotypic, and clinical features before establishing a final disease diagnosis. This review seeks to illustrate the comparative similarities and differences in the diagnosis of canine lymphoma through the presentation of the microscopic and immunophenotypic features of its most common forms.

Nasal Cavity and Paranasal Sinuses

The nasal cavity and paranasal sinuses occupy the top of the upper respiratory tract and form pneumatic spaces connected with the atmosphere. They are located immediately beneath the base of the cranium, where crucial vital structures are harbored. From this region, very much exposed to airborne agents, arise some of the more complex and rare benign and malignant lesions seen in humans, whose difficulties in interpretation make this remarkable territory one of the most challenging in the practice of surgical pathology.

Contents of this chapter cover inflammations and infections, polyps and pseudotumors, fungal and midfacial destructive granulomatous lesions, as well as benign, borderline, and malignant neoplasms. Among the neoplasms, emphasis is made on those entities characteristic or even unique for the sinonasal region, such as Schneiderian papillomas, glomangiopericytoma, intestinal- and non-intestinal-type adenocarcinomas, olfactory neuroblastoma, nasal-type NK-/T-cell lymphoma, and teratocarcinosarcoma. Moreover, recently recognized entities involving this territory, i.e., HPV-related non-keratinizing carcinoma, NUT carcinoma, and SMARCB1-deficient basaloid carcinoma, are also discussed in the light of their specific molecular findings. Furthermore, the text is accompanied by numerous classical and recent references, several tables, and 100 illustrations.

Pathogenetic and diagnostic significance of microRNA deregulation in peripheral T-cell lymphoma not otherwise specified

Peripheral T-cell lymphomas not otherwise specified (PTCLs/NOS) are rare and aggressive tumours whose molecular pathogenesis and diagnosis are still challenging. The microRNA (miRNA) profile of 23 PTCLs/NOS was generated and compared with that of normal T-lymphocytes (CD4+, CD8+, naive, activated). The differentially expressed miRNA signature was compared with the gene expression profile (GEP) of the same neoplasms. The obtained gene patterns were tested in an independent cohort of PTCLs/NOS. The miRNA profile of PTCLs/NOS then was compared with that of 10 angioimmunoblastic T-cell lymphomas (AITLs), 6 anaplastic large-cell lymphomas (ALCLs)/ALK+ and 6 ALCLs/ALK-. Differentially expressed miRNAs were validated in an independent set of 20 PTCLs/NOS, 20 AITLs, 19 ALCLs/ALK- and 15 ALCLs/ALK+. Two hundred and thirty-six miRNAs were found to differentiate PTCLs/NOS from activated T-lymphocytes. To assess which miRNAs impacted on GEP, a multistep analysis was performed, which identified all miRNAs inversely correlated to different potential target genes. One of the most discriminant miRNAs was selected and its expression was found to affect the global GEP of the tumours. Moreover, two sets of miRNAs were identified distinguishing PTCL/NOS from AITL and ALCL/ALK-, respectively. The diagnostic accuracy of this tool was very high (83.54%) and its prognostic value validated.

Past, present and future treatment strategies in peripheral T-cell lymphomas

SUMMARY 

Nodal peripheral T-cell lymphomas (PTCLs) are very aggressive tumors characterized by poor response to conventional chemotherapy and dismal prognosis. Recent evidence has indicated that, at least for patients aged less than 60 years, frontline high-dose chemotherapy followed by autologous stem cell transplantation can be an effective strategy. Unfortunately, however, a significant fraction of patients cannot benefit from this approach, due to age, poor performance status or early relapse. In addition, a percentage of transplanted patients eventually relapse. In this article, based on their experience and on the most recent literature, the authors review the current concept on PTCL treatment, focusing on the most common PTCL nodal subtypes.

Molecular genetics of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are rare neoplasms that in most instances respond poorly to conventional chemotherapies. Four varieties--PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK+ anaplastic T-cell lymphoma (ALCL), and ALK- ALCL--account for about 60 % of them. Their classification is difficult because of the wide spectrum of morphologic features and the lack of robust immunohistochemical markers. Thus, high-throughput technologies can importantly contribute to their better understanding. In particular, gene expression profiling has cleared the borders among PTCL/NOS, ALK- ALCL and AITL. In fact, gene signatures have been developed even from formalin-fixed paraffin-embedded tissue samples that definitely distinguish one tumor from the other(s). This has important practical implications: for instance on routine diagnostics PTCL/NOS expressing CD30 can be easily confused with ALK- ALCL, but has a much worse prognosis. Therefore, the clear-cut distinction between the two conditions is pivotal to understand the results of ongoing trials with Brentuximab Vedotin, targeting the CD30 molecule. Besides improving the diagnosis, molecular studies have provided the rationale for the usage of novel drugs in the setting of PTCLs, such as ALK inhibitors in ALK+ ALCL, anti-angiogenetic drugs in AITL, and tyrosine kinase inhibitors in PTCL/NOS and ALK+ and ALK- ALCLs.

Molecular profiling improves classification and prognostication of nodal peripheral T-cell lymphomas: results of a phase III diagnostic accuracy study

PURPOSE

The differential diagnosis among the commonest peripheral T-cell lymphomas (PTCLs; ie, PTCL not otherwise specified [NOS], angioimmunoblastic T-cell lymphoma [AITL], and anaplastic large-cell lymphoma [ALCL]) is difficult, with the morphologic and phenotypic features largely overlapping. We performed a phase III diagnostic accuracy study to test the ability of gene expression profiles (GEPs; index test) to identify PTCL subtype.

METHODS

We studied 244 PTCLs, including 158 PTCLs NOS, 63 AITLs, and 23 ALK-negative ALCLs. The GEP-based classification method was established on a support vector machine algorithm, and the reference standard was an expert pathologic diagnosis according to WHO classification.

RESULTS

First, we identified molecular signatures (molecular classifier [MC]) discriminating either AITL and ALK-negative ALCL from PTCL NOS in a training set. Of note, the MC was developed in formalin-fixed paraffin-embedded (FFPE) samples and validated in both FFPE and frozen tissues. Second, we found that the overall accuracy of the MC was remarkable: 98% to 77% for AITL and 98% to 93% for ALK-negative ALCL in test and validation sets of patient cases, respectively. Furthermore, we found that the MC significantly improved the prognostic stratification of patients with PTCL. Particularly, it enhanced the distinction of ALK-negative ALCL from PTCL NOS, especially from some CD30+ PTCL NOS with uncertain morphology. Finally, MC discriminated some T-follicular helper (Tfh) PTCL NOS from AITL, providing further evidence that a group of PTCLs NOS shares a Tfh derivation with but is distinct from AITL.

CONCLUSION

Our findings support the usage of an MC as additional tool in the diagnostic workup of nodal PTCL.

Non Hodgkin T cell lymphoma: an atypical clinical presentation

Cytotoxic lymphomas comprise a spectrum of peripheral T-cell lymphomas that can have a initial or late cutaneous presentation. We describe a 46-year-old man from Cape Verde, with a dermatosis involving his face and trunk, consisting of monomorphic papules with a smooth surface and both motor and sensory polyneuropathy.The hypothesis of leprosy was supported by the clinical and initial hystopathological findings and the patient was referred to our hospital with suspected Hansen's disease. In the new skin and lymph node biopsies a lymphocyte population was identified whose immunohystochemistry study allowed the diagnosis of T-cell lymphoma with expression of cytotoxic markers. The patient was started on chemotherapy with initial remission of the skin lesions but, subsequently, progression of systemic disease.

Molecular profiling reveals prognostically significant subtypes of canine lymphoma

We performed genomewide gene expression analysis of 35 samples representing 6 common histologic subtypes of canine lymphoma and bioinformatics analyses to define their molecular characteristics. Three major groups were defined on the basis of gene expression profiles: (1) low-grade T-cell lymphoma, composed entirely by T-zone lymphoma; (2) high-grade T-cell lymphoma, consisting of lymphoblastic T-cell lymphoma and peripheral T-cell lymphoma not otherwise specified; and (3) B-cell lymphoma, consisting of marginal B-cell lymphoma, diffuse large B-cell lymphoma, and Burkitt lymphoma. Interspecies comparative analyses of gene expression profiles also showed that marginal B-cell lymphoma and diffuse large B-cell lymphoma in dogs and humans might represent a continuum of disease with similar drivers. The classification of these diverse tumors into 3 subgroups was prognostically significant, as the groups were directly correlated with event-free survival. Finally, we developed a benchtop diagnostic test based on expression of 4 genes that can robustly classify canine lymphomas into one of these 3 subgroups, enabling a direct clinical application for our results.

New molecular insights into peripheral T cell lymphomas

Peripheral T cell lymphomas (PTCLs) are heterogeneous neoplasms and represent about 12% of all lymphoid malignancies. They are often regarded as "orphan diseases," a designation that does not reflect their real incidence but rather signifies the difficulties encountered in their classification, diagnosis, and treatment. Here we revise the current understanding of the pathobiological characteristics of the most common nodal PTCLs by focusing on the contribution given by high-throughput technologies and the identification of potential therapeutic targets proposed by translational studies.

Enforced expression of Lin28b leads to impaired T-cell development, release of inflammatory cytokines, and peripheral T-cell lymphoma

LIN28A and LIN28B, the mammalian homologs of lin-28, are implicated in malignant transformation in part because of their ability to promote degradation of the let-7 family of miRs. In the present study, we show that overexpression of Lin28b in vivo leads to an aggressive peripheral T-cell lymphoma (PTCL) characterized by widespread infiltration of parenchymal organs with malignant CD4(+) cells. Similar to patients with PTCL, Lin28b-transgenic mice show signs of inflammation such as eosinophilia, increased C-reactive protein, release of inflammatory cytokines, and pleural effusion. The PTCLs that develop in Lin28b mice are derived from activated T cells and show decreased let-7 expression, increased Il6 expression, activation of NF-κB, and infiltration of B cells, all resulting in an inflammatory microenvironment. In addition, LIN28B is overexpressed 7.5-fold in PTCL patient samples compared with activated CD4(+) cells. The results of the present study demonstrate for the first time that Lin28b can transform primary cells in vivo, identify a previously unsuspected link between Lin28b and PTCL, and provide a unique animal model for the study of PTCL biology and therapy.

Targeted molecular therapy in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are rare neoplasms constituting a heterogeneous group of diseases. At present, available chemotherapy regimens that have improved outcomes in B-cell lymphomas appear to be less efficacious in the context of PTCLs and, thus, alternative strategies are warranted. In the last few years, based on the recent, deeper understanding of PTCL biology, several molecules and/or pathways have been proposed for targeted therapy in this setting, including surface antigens, tyrosine kinases, the NF-κB pathway, folate metabolism, histone modification and others. Of particular interest, histone deacetylase and proteasome inhibitors, as well as novel chemotherapeutic agents such as pralatrexate, have already demonstrated efficacy in PTCL therapy. In addition, a strong biological rationale and early clinical evidence supports the future study of tyrosine kinase inhibitors in this setting. In this article, the authors review the available literature on targeted therapy in PTCLs and also, based on their own experience, discuss potential opportunities in this intriguing area.