Peripheral T-cell lymphoma with a T follicular-helper phenotype: A different entity? Results of the Spanish Real-T study.

Nodal peripheral T-cell lymphoma (PTCL) with a T follicular helper phenotype (PTCL-TFH) is a new type of PTCL. We aimed to define its clinical characteristics and prognosis compared to PTCL not otherwise specified (PTCL-NOS) and angioimmunoblastic T-cell lymphoma (AITL). This retrospective observational study included 175 patients diagnosed with PTCL between 2008 and 2013 in 13 Spanish sites. Patient diagnosis was centrally reviewed, and patients were reclassified according to the World Health Organization (WHO) 2016 criteria: 21 patients as PTCL-NOS, 55 as AITL and 23 as PTCL-TFH. Median follow-up was 56.07 months (95% CI 38.7-73.4). Progression-free survival (PFS) and overall survival (OS) were significantly higher in patients with PTCL-TFH than in those with PTCL-NOS and AITL (PFS, 24.6 months vs. 4.6 and 7.8 months, respectively, p = 0.002; OS, 52.6 months vs. 10.0 and 19.3 months, respectively, p < 0.001). Histological diagnosis maintained an independent influence on both PFS (hazard ratio [HR] 4.1 vs. PTCL-NOS, p = 0.008; HR 2.6 vs. AITL, p = 0.047) and OS (HR 5.7 vs. PTCL-NOS, p = 0.004; HR 2.6 vs. AITL, p = 0.096), regardless of the International Prognostic Index. These results suggest that PTCL-TFH could have more favourable features and prognosis than the other PTCL subtypes, although larger series are needed to corroborate these findings.

An integrated prognostic model for diffuse large B-cell lymphoma treated with immunochemotherapy.

Diffuse large B-cell lymphoma (DLBCL), the most frequent non-Hodgkin's lymphoma subtype, is characterized by strong biological, morphological, and clinical heterogeneity, but patients are treated with immunochemotherapy in a relatively homogeneous way. Here, we have used a customized NanoString platform to analyze a series of 197 homogeneously treated DLBCL cases. The platform includes the most relevant genes or signatures known to be useful for predicting response to R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone) in DLBCL cases. We generated a risk score that combines the International Prognostic Index with cell of origin and double expression of MYC/BCL2, and stratified the series into three groups, yielding hazard ratios from 0.15 to 5.49 for overall survival, and from 0.17 to 5.04 for progression-free survival. Group differences were highly significant (p < 0.0001), and the scoring system was applicable to younger patients (<60 years of age) and patients with advanced or localized stages of the disease. Results were validated in an independent dataset from 166 DLBCL patients treated in two distinct clinical trials. This risk score combines clinical and biological data in a model that can be used to integrate biological variables into the prognostic models for DLBCL cases.

Plasmacytoid Dendritic Cell Dermatosis Associated to Myeloproliferative/Myelodysplastic Neoplasms.

Cutaneous lesions in the setting of myeloproliferative neoplasms and myelodysplastic syndromes are poorly understood. We report 6 patients with pruritic papular eruptions composed of mature T-lymphocytes with large clusters of CD123-positive cells. Double immunohistochemical studies demonstrated a lack of myeloid cell nuclear differentiation antigen in the CD123-positive cells, which expressed SPIB, confirming that they were mature plasmacytoid dendritic cells. Four patients were diagnosed with chronic myelomonocytic leukemia and 2 with myelodysplastic syndromes (AREB-I and myelodysplastic syndromes with 5q deletion, respectively). All patients had a long history of hematological alterations, mainly thrombocytopenia, preceding the cutaneous disorder. Nevertheless, the skin lesions developed in all cases coincidentally with either progression or full-establishment of their hematological disease. Most cutaneous lesions disappeared spontaneously or after corticosteroid treatment. Molecular studies performed in both bone marrow and cutaneous lesions in 2 patients demonstrated the same mutational profile, confirming the specific, neoplastic nature of these mature plasmacytoid dendritic cells-composed cutaneous lesions.

Peripheral T-cell lymphoma: molecular profiling recognizes subclasses and identifies prognostic markers.

Peripheral T-cell lymphoma (PTCL) is a clinically aggressive disease, with a poor response to therapy and a low overall survival rate of approximately 30% after 5 years. We have analyzed a series of 105 cases with a diagnosis of PTCL using a customized NanoString platform (NanoString Technologies, Seattle, WA) that includes 208 genes associated with T-cell differentiation, oncogenes and tumor suppressor genes, deregulated pathways, and stromal cell subpopulations. A comparative analysis of the various histological types of PTCL (angioimmunoblastic T-cell lymphoma [AITL]; PTCL with T follicular helper [TFH] phenotype; PTCL not otherwise specified [NOS]) showed that specific sets of genes were associated with each of the diagnoses. These included TFH markers, cytotoxic markers, and genes whose expression was a surrogate for specific cellular subpopulations, including follicular dendritic cells, mast cells, and genes belonging to precise survival (NF-κB) and other pathways. Furthermore, the mutational profile was analyzed using a custom panel that targeted 62 genes in 76 cases distributed in AITL, PTCL-TFH, and PTCL-NOS. The main differences among the 3 nodal PTCL classes involved the RHOAG17V mutations (P < .0001), which were approximately twice as frequent in AITL (34.09%) as in PTCL-TFH (16.66%) cases but were not detected in PTCL-NOS. A multivariate analysis identified gene sets that allowed the series of cases to be stratified into different risk groups. This study supports and validates the current division of PTCL into these 3 categories, identifies sets of markers that can be used for a more precise diagnosis, and recognizes the expression of B-cell genes as an IPI-independent prognostic factor for AITL.

Update on peripheral T-cell lymphomas with T-helper phenotype: Are there too many subtypes?

Follicular helper T (TFH) cells are the providers of T-cell help to B-cells in the development of germinal centers and for the generation of most class-switched antibodies. The markers most commonly associated with TFH activity are IL21, IL4, CD40L, BCL6, SAP, CXCR5/CXCL13, and ICOS. T-cell lymphoma genomic studies have shown that different T-cell lymphoma types express signatures typical for TFH cells, this including angioimmunoblastic T-cell lymphoma (AITL), a related condition termed peripheral T-cell lymphoma with TFH phenotype and primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder. Angioimmunoblastic T-cell lymphoma is a well-established entity, a clinically aggressive disease with a survival of 30% OS after 5 years. Molecular and clinical studies have confirmed this as a well-established clinicopathological entity with relatively specific gene mutations, including mutations found in hematopoietic precursor cells and others. Peripheral T-cell lymphoma with TFH phenotype is an associated disorder with histology of PTCL but a TFH phenotype, as defined by the expression of 2-3 immunohistochemical markers. Molecular studies on this entity are showing a partial overlap with AITL. Primary cutaneous CD4+ small/medium lymphoproliferative disorder is an entirely different process that takes place in the skin, showing frank cytologic atypia, monoclonal TCR rearrangement and TFH phenotype in the context of a clinically benign lesion. Here we review the main clinical, molecular and diagnostic features of these three lymphoproliferative processes.

Pagetoid reticulosis in a 13-year old female. A unique immunohistochemical profile.

Pagetoid reticulosis (PR) is a rare lymphoproliferative disorder with indolent behavior considered a variant of mycosis fungoides. It is characterized by marked epidermotropism of the neoplastic lymphocytes. Since its original description, five cases have been reported in children. We report a new case of PR with an immunohistochemical profile not previously described in children.

Large Cells With CD30 Expression and Hodgkin-like Features in Primary Cutaneous Marginal Zone B-Cell Lymphoma: A Study of 13 Cases.

The presence of CD30 cells in cutaneous lymphomas has come to prominence in recent years as a potential diagnostic and therapeutic marker. In primary cutaneous marginal zone B-cell lymphomas, the presence of large CD30 cells with Hodgkin-like features and their significance have not yet been studied. Here we describe the main clinical, histologic, immunophenotypic, and molecular characteristics of 13 cases of primary cutaneous marginal zone lymphomas featuring >10% of CD30 large cells, and analyze their relationship with histologic and clinical progression of the disease and with other morphologic and immunophenotypic features. We report 10 male and 3 female patients, 4 with early-local disease and 8 with locoregional advanced disease without extracutaneous involvement but with a high relapse rate of 69%. We describe an association between a high level of CD30 expression and disease progression, with increased clinical recurrence in cases with >15% of CD30 cells. We also discuss the differential diagnosis with other cutaneous and systemic lymphomas, especially Hodgkin lymphoma.

Mycosis Fungoides Associated With Lesions in the Spectrum of Primary Cutaneous CD30+ Lymphoproliferative Disorders: The Same Process or 3 Coexisting Lymphomas?

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma, primary cutaneous CD30 lymphoproliferative disorders (pc CD30 LPD) being the second most prevalent. There is evidence that MF and pc CD30 LPD may coexist and share T-cell clonality, suggesting a common origin. These findings were supported by a T-cell receptor clonality assessment by the polymerase chain reaction coupled with capillary electrophoresis, although results produced by this method may be ambiguous. We describe an otherwise healthy 46-year-old man who developed, over the course of 5 months, a tumor consisting of primary cutaneous anaplastic large cell lymphoma and, subsequently, several papules of lymphomatoid papulosis (LyP). Both lymphomas appeared on a single patch of MF, which had been present on the patient's right buttock for at least 2 years. T-cell receptor clonality of the 3 types of neoplastic lesions and apparently non-involved skin were assessed by a next-generation sequencing-based method. We found that MF, primary cutaneous anaplastic large cell lymphoma and LyP harbored the same top 2 clones. Non-involved skin harbored other T-cell clones. In this patient, these findings suggest that MF, LyP and pc CD30 LPD were different clinicopathological manifestations arising from the neoplastic proliferation of the same T-cell clone.

Unraveling transformation of follicular lymphoma to diffuse large B-cell lymphoma.

Follicular lymphoma (FL) is an indolent but largely incurable disease. Some patients suffer histological transformation to a more aggressive subtype with poorer prognosis. This study aimed to improve our understanding of the genetics underlying FL histological transformation, and to identify genetic drivers or promoters of the transformation by elucidating the differences between FL samples from patients who did and did not transform. We conducted targeted massive parallel sequencing of 22 pre-transformed FL/transformed diffuse large B-cell lymphoma pairs and 20 diagnostic samples from non-transformed FL patients. Additionally, 22 matched samples from 11 transformed FL patients (pre-transformed FL and diffuse large B-cell lymphoma) and 9 non-transformed FLs were studied for copy number variation using SNP arrays. We identified recurrently mutated genes that were enriched at transformation, most notably LRP1B, GNA13 and POU2AF1, which have roles in B-cell differentiation, GC architecture and migration. Mutations in POU2AF1 might be associated with lower levels of expression, were more frequent in transformed FLs, and seemed to be specific to transformed- compared with de novo-diffuse large B-cell lymphomas. Pre-transformed FLs carried more mutations per sample and had greater subclonal heterogeneity than non-transformed FLs. Finally, we identified four mutated genes in FL samples that differed between patients who did and did not transform: NOTCH2, DTX1, UBE2A and HIST1H1E. The presence of mutations in these genes was associated with shorter time to transformation when mutated in the FL biopsies. This information might be useful for identifying patients at higher risk of transformation.

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.

The Spectrum of EBV-Positive Mucocutaneous Ulcer: A Study of 9 Cases.

We describe a series of 9 patients with Epstein-Barr virus (EBV)-positive mucocutaneous lymphoproliferative lesions that broadens the concept of EBV-positive mucocutaneous ulcer. We report 5 female and 4 male patients, with an average age of 74 years (range, 55 to 87 y), 2 of whom were HIV-positive. The lesions were located in the oropharynx, skin, and rectal and/or genital mucosa. Histopathologically, 6 cases showed a polymorphic pattern and 3 had a monomorphic and diffuse one, with angiotropism in 4 cases (2 each with the polymorphic and monomorphic patterns). Three of the cases expressed PDL1. In addition to its presence in the neoplastic lymphoid cells, EBV was also detected in adjacent epithelial cells in an oropharyngeal lesion. All cases responded to local therapy or adapted systemic chemotherapy in selected cases. This series extends the spectrum of this disorder to include some HIV-positive cases, patients with multiple lesions confined to a single anatomic area, lesions with an angiocentric pattern, and some cases with monomorphous large-cell cytology. We discuss the differential clinicopathologic diagnosis of this disorder and that of classic EBV large B-cell lymphoma.

Mycosis fungoides progression could be regulated by microRNAs.

Differentiating early mycosis fungoides (MF) from inflammatory dermatitis is a challenge. We compare the differential expression profile of early-stage MF samples and benign inflammatory dermatoses using microRNA (miRNA) arrays. 114 miRNAs were found to be dysregulated between these entities. The seven most differentially expressed miRNAs between these two conditions were further analyzed using RT-PCR in two series comprising 38 samples of early MFs and 18 samples of inflammatory dermatitis. A series of 51 paraffin-embedded samples belonging to paired stages of 16 MF patients was also analyzed. MiRNAs 26a, 222, 181a and 146a were differentially expressed between tumoral and inflammatory conditions. Two of these miRNAs (miRNA-181a and miRNA-146a) were significantly deregulated between early and advanced MF stages. Bioinformatic analysis showed FOXP3 expression to be regulated by these miRNAs. Immunohistochemistry revealed the level of FOXP3 expression to be lower in tumoral MFs than in plaque lesions in paraffin-embedded tissue. A functional study confirmed that both miRNAs diminished FOXP3 expression when overexpressed in CTCL cells. The data presented here suggest that the analysis of a restricted number of miRNAs (26a, 222, 181a and 146a) could be sufficient to differentiate tumoral from reactive conditions. Moreover, these miRNAs seem to be involved in MF progression.

Overlap at the molecular and immunohistochemical levels between angioimmunoblastic T-cell lymphoma and a subgroup of peripheral T-cell lymphomas without specific morphological features.

The overlap of morphology and immunophenotype between angioimmunoblastic T-cell lymphoma (AITL) and other nodal peripheral T-cell lymphomas (n-PTCLs) is a matter of current interest whose clinical relevance and pathogenic background have not been fully established. We studied a series of 98 n-PTCL samples (comprising 57 AITL and 41 PTCL-NOS) with five TFH antibodies (CD10, BCL-6, PD-1, CXCL13, ICOS), looked for mutations in five of the genes most frequently mutated in AITL (TET2, DNMT3A, IDH2, RHOA and PLCG1) using the Next-Generation-Sequencing Ion Torrent platform, and measured the correlations of these characteristics with morphology and clinical features. The percentage of mutations in the RHOA and TET2 genes was similar (23.5% of cases). PLCG1 was mutated in 14.3%, IDH2 in 11.2% and DNMT3A in 7.1% of cases, respectively. In the complete series, mutations in RHOA gene were associated with the presence of mutations in IDH2, TET2 and DNMT3A (p < 0.001, p = 0.043, and p = 0.029, respectively). Fourteen cases featured RHOA mutations without TET2 mutations. A close relationship was found between the presence of these mutations and a TFH-phenotype in AITL and PTCL-NOS patients. Interestingly, BCL-6 expression was the only TFH marker differentially expressed between AITL and PTCL-NOS cases. There were many fewer mutated cases than there were cases with a TFH phenotype. Overall, these data suggest alternative ways by which neoplastic T-cells overexpress these proteins. On the other hand, no clinical or survival differences were found between any of the recognized subgroups of patients with respect to their immunohistochemistry or mutational profile.

Cutaneous intravascular natural killer/T cell lymphoma with peculiar immunophenotype.

Intravascular lymphoma (IVL) is a rare entity. Most cases are a variant of extranodal diffuse large B cell lymphoma, and fewer than 10% of the published cases are of T cell origin. Only intravascular B cell lymphoma is recognized as a distinct entity in the most recent World Health Organization (WHO) classification of lymphoproliferative disorders. We describe a case of cutaneous natural killer (NK)/T IVL, with a cytotoxic immunophenotype and Epstein-Barr virus (EBV) positivity. However, our case was immunohistochemically negative not only for T cell receptor (TCR)-ßF1 and TCR-γ (TCR-silent), but also for CD56, making it the first triple-negative NK/T IVL case to be described. We urge recognition of this NK/T cell lineage intravascular lymphoma due to its particular immunophenotypical profile and its unvarying relationship with EBV. Its occurrence should not be considered a coincidence, but rather a key aspect of the pathogenic background of this haematological neoplasm.

MYD88 L265P mutation in cutaneous involvement by Waldenström macroglobulinemia.

Cutaneous manifestations of Waldenström macroglobulinemia (WM) may occur because of several mechanisms, the least common being direct skin infiltration by neoplastic cells. We report a case of patient that after 4-year history of indolent WM developed skin infiltration by lymphoplasmacytoid cells in the form of a small, mildly indurated plaque on the anterior chest. MYD88 L265P mutation was detected both in the previous bone marrow biopsy and in the cutaneous lesion. We review the impact of this new genetic tool in the diagnosis and treatment of lymphoplasmacytic proliferations.