Disease-biased and shared characteristics of the immunoglobulin gene repertoires in marginal zone B cell lymphoproliferations.

The B cell receptor immunoglobulin (Ig) gene repertoires of marginal zone (MZ) lymphoproliferations were analyzed in order to obtain insight into their ontogenetic relationships. Our cohort included cases with MZ lymphomas (n = 488), i.e. splenic (SMZL), nodal (NMZL) and extranodal (ENMZL), as well as provisional entities (n = 76), according to the WHO classification. The most striking Ig gene repertoire skewing was observed in SMZL. However, restrictions were also identified in all other MZ lymphomas studied, particularly ENMZL, with significantly different Ig gene distributions depending on the primary site of involvement. Cross-entity comparisons of the MZ Ig sequence dataset with a large dataset of Ig sequences (MZ-related or not; n = 65 837) revealed four major clusters of cases sharing homologous ('public') heavy variable complementarity-determining region 3. These clusters included rearrangements from SMZL, ENMZL (gastric, salivary gland, ocular adnexa), chronic lymphocytic leukemia, but also rheumatoid factors and non-malignant splenic MZ cells. In conclusion, different MZ lymphomas display biased immunogenetic signatures indicating distinct antigen exposure histories. The existence of rare public stereotypes raises the intriguing possibility that common, pathogen-triggered, immune-mediated mechanisms may result in diverse B lymphoproliferations due to targeting versatile progenitor B cells and/or operating in particular microenvironments. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Numerous Ontogenetic Roads to Mantle Cell Lymphoma: Immunogenetic and Immunohistochemical Evidence.

To obtain insight into the ontogeny of mantle cell lymphoma (MCL), we assessed 206 patients from a morphological, immunohistochemical, and immunogenetic perspective. Our series included nodal (n = 151), extranodal (n = 28), and primary splenic (n = 27) MCL cases. Skewing of the immunoglobulin heavy variable (IGHV) gene repertoire was noted, with only four IGHV genes accounting for 46% of cases and approximately 70% of cases (107/154) bearing an imprint of somatic hypermutation (SHM) ranging from minimal to pronounced. Interestingly, a distinctive immunophenotypic and immunogenetic profile was identified for primary splenic MCL, which was enriched for DBA.44-positive cases (P < 0.001) and used the IGHV1-8 gene more frequently (P = 0.02) compared to nodal or extranodal cases, alluding to distinct immunopathogenetic and antigen selection processes. Expression of CD27 (considered a marker of activated B cells) was generally dissociated from SHM and was more prevalent in cases with no or minimal/borderline SHM. These findings support the idea that antigen drive is relevant for most MCL cases, although the specific antigens and the precise location of affinity maturation remain to be elucidated. Moreover, they raise the intriguing hypothesis of multiple cellular origins for MCL.

Frequent NFKBIE deletions are associated with poor outcome in primary mediastinal B-cell lymphoma.

We recently reported a truncating deletion in the NFKBIE gene, which encodes IκBε, a negative feedback regulator of NF-κB, in clinically aggressive chronic lymphocytic leukemia (CLL). Because preliminary data indicate enrichment of NFKBIE aberrations in other lymphoid malignancies, we screened a large patient cohort (n = 1460) diagnosed with different lymphoid neoplasms. While NFKBIE deletions were infrequent in follicular lymphoma, splenic marginal zone lymphoma, and T-cell acute lymphoblastic leukemia (<2%), slightly higher frequencies were seen in diffuse large B-cell lymphoma, mantle cell lymphoma, and primary central nervous system lymphoma (3% to 4%). In contrast, a remarkably high frequency of NFKBIE aberrations (46/203 cases [22.7%]) was observed in primary mediastinal B-cell lymphoma (PMBL) and Hodgkin lymphoma (3/11 cases [27.3%]). NFKBIE-deleted PMBL patients were more often therapy refractory (P = .022) and displayed inferior outcome compared with wild-type patients (5-year survival, 59% vs 78%; P = .034); however, they appeared to benefit from radiotherapy (P =022) and rituximab-containing regimens (P = .074). NFKBIE aberrations remained an independent factor in multivariate analysis (P = .003) and when restricting the analysis to immunochemotherapy-treated patients (P = .008). Whole-exome sequencing and gene expression profiling verified the importance of NF-κB deregulation in PMBL. In summary, we identify NFKBIE aberrations as a common genetic event across B-cell malignancies and highlight NFKBIE deletions as a novel poor-prognostic marker in PMBL.

An Immunogenetic Signature of Ongoing Antigen Interactions in Splenic Marginal Zone Lymphoma Expressing IGHV1-2*04 Receptors.

PURPOSE: Prompted by the extensive biases in the immunoglobulin (IG) gene repertoire of splenic marginal-zone lymphoma (SMZL), supporting antigen selection in SMZL ontogeny, we sought to investigate whether antigen involvement is also relevant post-transformation. EXPERIMENTAL DESIGN: We conducted a large-scale subcloning study of the IG rearrangements of 40 SMZL cases aimed at assessing intraclonal diversification (ID) due to ongoing somatic hypermutation (SHM). RESULTS: ID was identified in 17 of 21 (81%) rearrangements using the immunoglobulin heavy variable (IGHV)1-2*04 gene versus 8 of 19 (40%) rearrangements utilizing other IGHV genes (P= 0.001). ID was also evident in most analyzed IG light chain gene rearrangements, albeit was more limited compared with IG heavy chains. Identical sequence changes were shared by subclones from different patients utilizing the IGHV1-2*04 gene, confirming restricted ongoing SHM profiles. Non-IGHV1-2*04 cases displayed both a lower number of ongoing SHMs and a lack of shared mutations (per group of cases utilizing the same IGHV gene). CONCLUSIONS: These findings support ongoing antigen involvement in a sizable portion of SMZL and further argue that IGHV1-2*04 SMZL may represent a distinct molecular subtype of the disease.

Molecular evidence for antigen drive in the natural history of mantle cell lymphoma.

To further our understanding about antigen involvement in mantle cell lymphoma (MCL), we analyzed the expression levels of activation-induced cytidine deaminase (AID), a key player in B-cell responses to antigen triggering, in 133 MCL cases; assessed the functionality of AID by evaluating in vivo class switch recombination in 52 MCL cases; and sought for indications of ongoing antigen interactions by exploring intraclonal diversification within 14 MCL cases. The AID full-length transcript and the most frequent splice variants (AID-ΔE4a, AID-ΔE) were detected in 128 (96.2%), 96 (72.2%), and 130 cases (97.7%), respectively. Higher AID full-length transcript levels were significantly associated (P < 0.001) with lack of somatic hypermutation within the clonotypic immunoglobulin heavy variable (IGHV) genes. Median AID transcript levels were higher in lymph node material compared to cases in which peripheral blood was analyzed, implying that clonal behavior is influenced by the microenvironment. Switched tumor-derived IGHV-IGHD-IGHJ transcripts were identified in 5 of 52 cases (9.6%), all of which displayed somatic hypermutation and AID-mRNA expression. Finally, although most cases exhibited low levels of intraclonal diversification, analysis of the mutational activity revealed a precise targeting of somatic hypermutation indicative of an active, ongoing interaction with antigen(s). Collectively, these findings strongly allude to antigen involvement in the natural history of MCL, further challenging the notion of antigen naivety.

Association of clinicopathological characteristics with secondary neoplastic lymphoproliferative disorders in patients with lymphomatoid papulosis.

Lymphomatoid papulosis (LyP) refers to an indolent cutaneous lymphoma. The association of prognostic clinicopathological risk factors with a second hematologic malignancy has not yet been determined. We investigated the prognostic effect of clinicopathological characteristics on the occurrence of a second lymphoma, as well as the first-line treatment, in 24 patients diagnosed with LyP using logistic regression models. We showed that lymphoma occurrence was associated with a lower mean age at onset of LyP symptoms, histological types B and C, head-located LyP lesions and a higher frequency of LyP recurrences. In multivariate analyses, histologic type A was associated with a lower risk of second lymphoma (odds ratio [OR] = 0.12, 95% confidence interval [CI] 0.014-0.98; p = 0.045) adjusting for age of LyP first symptomatology, and an important increased lymphoma-free survival rate (long-rank test; p = 0.06). Clinicopathological characteristics are important in defining the clearance or persistence of LyP lesions and may predict the occurrence of a second lymphoma.

In situ assessment of PI3K and PTEN alterations in mycosis fungoides: correlation with clinicopathological features.

Deregulated signalling through phosphatidylinositol 3-kinase (PI3K) pathway plays a critical role in tumour initiation and progression. We have already shown that AKT is activated in skin lesions in Mycosis Fungoides (MF) and we herein further investigate the frequency and clinical significance of PTEN and PI3K at the protein and at the DNA level as well as the presence of AKT1 mutations in skin lesions from 50 patients with MF clinical stages I-IV in relation to clinicopathological features. Increased p-AKT expression correlated with poor prognosis in plaques (P = 0.0198), whereas p-AKT was an independent predictor of poor survival in the entire cohort (P = 0.017, HR = 1.012). PTEN cytoplasmic expression was found low or absent in all 77.3% of cases and inversely correlated with advanced clinical stages (P = 0.0744). Molecular analysis showed no AKT1 mutation, no PI3KCA copy number gain, only 1 case with PI3KCA mutation in exon 9 and 3 cases with PTEN mutations (7%) in exons 7, 8 and 5. The latter correlated with disease (P = 0.0253) and progression (P < 0.0001) free survival in tumour stage. Although activation of PI3K/AKT signalling pathway due to PTEN alterations is rarely attributed to abnormalities in PTEN, PI3K, and AKT1 genes, PTEN mutations exert a negative effect on patients' prognosis with tumours.

Plasmablastic lymphoma of the breast in an immunocompetent patient: long-lasting complete response induced by chemotherapy and autologous stem cell trasplantation.

BACKGROUND: Plasmablastic lymphoma (PBL) is a rare entity which is often causally related to infection by the Human Immunodeficiency Virus (HIV). Despite its predilection for oral cavity involvement, multiple cases of extra-oral involvement have been reported in the literature, more often among immunocompetent individuals. CASE REPORT: Herein we present the first case of primary PBL of the breast in an otherwise immunocompetent 36-year-old woman who was successfully treated with consolidation megatherapy and autologous stem cell transplantation. CONCLUSION: PBL carries a particularly poor prognosis and more intensive treatment is usually warranted. However, no treatment guidelines exist and treatment choices are made based on case reports and small retrospective case series.

PLCG1 mutations in cutaneous T-cell lymphomas.

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of primary cutaneous T-cell lymphoproliferative processes, mainly composed of mycosis fungoides and Sézary syndrome, the aggressive forms of which lack an effective treatment. The molecular pathogenesis of CTCL is largely unknown, although neoplastic cells show increased signaling from T-cell receptors (TCRs). DNAs from 11 patients with CTCL, both normal and tumoral, were target-enriched and sequenced by massive parallel sequencing for a selection of 524 TCR-signaling-related genes. Identified variants were validated by capillary sequencing. Multiple mutations were found that affected several signaling pathways, such as TCRs, nuclear factor κB, or Janus kinase/signal transducer and activator of transcription, but PLCG1 was found to be mutated in 3 samples, 2 of which featured a redundant mutation (c.1034T>C, S345F) in exon 11 that affects the PLCx protein catalytic domain. This mutation was further analyzed by quantitative polymerase chain reaction genotyping in a new cohort of 42 patients with CTCL, where it was found in 19% of samples. Immunohistochemical analysis for nuclear factor of activated T cells (NFAT) showed that PLCG1-mutated cases exhibited strong NFAT nuclear immunostaining. Functional studies demonstrated that PLCG1 mutants elicited increased downstream signaling toward NFAT activation, and inhibition of this pathway resulted in reduced CTCL cell proliferation and cell viability. Thus, increased proliferative and survival mechanisms in CTCL may partially depend on the acquisition of somatic mutations in PLCG1 and other genes that are essential for normal T-cell differentiation.

Familial CD3+ T large granular lymphocyte leukemia: evidence that genetic predisposition and antigen selection promote clonal cytotoxic T-cell responses.

CD3+ T-large granular lymphocyte (T-LGL) proliferations often present with cytopenias and splenomegaly and are linked to autoimmunity, especially rheumatoid arthritis and Felty's syndrome. We report here the intra-family occurrence of T-LGL leukemia in a father and son, both presenting with cytopenias and splenomegaly. Both patients carried the HLA-DRB1*04 allele, strongly associated with rheumatoid arthritis and Felty's syndrome, exhibited distinctive histopathological features suggestive of immune-mediated suppression of hematopoiesis and expressed a remarkably skewed T-cell receptor beta chain gene repertoire with overtime evolution (clonal drift). Immunoinformatics analysis and comparisons with clonotype sequences from various entities revealed (quasi)identities between (i) father and son, and (ii) father or son and patients with autoimmune disorders, T-LGL leukemia or chronic idiopathic neutropenia. Altogether, our results further corroborate antigen selection in the ontogeny of T-LGL leukemia and point to the interplay between genetics and the (micro)environment in shaping the outcome of cytotoxic T cell responses.

Clonal B-cell lymphocytosis exhibiting immunophenotypic features consistent with a marginal-zone origin: is this a distinct entity?

The biological and clinical significance of a clonal B-cell lymphocytosis with an immunophenotype consistent with marginal-zone origin (CBL-MZ) is poorly understood. We retrospectively evaluated 102 such cases with no clinical evidence to suggest a concurrent MZ lymphoma. Immunophenotyping revealed a clonal B-cell population with Matutes score ≤2 in all cases; 19/102 were weakly CD5 positive and all 35 cases tested expressed CD49d. Bone marrow biopsy exhibited mostly mixed patterns of small B-lymphocytic infiltration. A total of 48/66 (72.7%) cases had an abnormal karyotype. Immunogenetics revealed overusage of the IGHV4-34 gene and somatic hypermutation in 71/79 (89.8%) IGHV-IGHD-IGHJ gene rearrangements. With a median follow-up of 5 years, 85 cases remain stable (group A), whereas 17 cases (group B) progressed, of whom 15 developed splenomegaly. The clonal B-cell count, degree of marrow infiltration, immunophenotypic, or immunogenetic findings at diagnosis did not distinguish between the 2 groups. However, deletions of chromosome 7q were confined to group A and complex karyotypes were more frequent in group B. Although CBL-MZ may antedate SMZL/SLLU, most cases remain stable over time. These cases, not readily classifiable within the World Heath Organization classification, raise the possibility that CBL-MZ should be considered as a new provisional entity within the spectrum of clonal MZ disorders.

Two main genetic pathways lead to the transformation of chronic lymphocytic leukemia to Richter syndrome.

Richter syndrome (RS) occurs in up to 15% of patients with chronic lymphocytic leukemia (CLL). Although RS, usually represented by the histologic transformation to a diffuse large B-cell lymphoma (DLBCL), is associated with a very poor outcome, especially when clonally related to the preexisting CLL, the mechanisms leading to RS have not been clarified. To better understand the pathogenesis of RS, we analyzed a series of cases including 59 RS, 28 CLL phase of RS, 315 CLL, and 127 de novo DLBCL. RS demonstrated a genomic complexity intermediate between CLL and DLBCL. Cell-cycle deregulation via inactivation of TP53 and of CDKN2A was a main mechanism in the histologic transformation from CLL phase, being present in approximately one half of the cases, and affected the outcome of the RS patients. A second major subgroup was characterized by the presence of trisomy 12 and comprised one third of the cases. Although RS shared some of the lesions seen in de novo DLBCL, its genomic profile was clearly separate. The CLL phase preceding RS had not a generalized increase in genomic complexity compared with untransformed CLL, but it presented clear differences in the frequency of specific genetic lesions.

A comprehensive immunohistochemical approach of AKT/mTOR pathway and p-STAT3 in mycosis fungoides.

BACKGROUND: Although the expression pattern of phosphorylated (p)-mTOR pathway components has attracted scientific interest in several neoplasms, to our knowledge, there is no published information regarding its significance in mycosis fungoides (MF). OBJECTIVE: We sought to perform a comprehensive simultaneous assessment of key members of AKT/mTOR pathway along with p-extracellular signal-regulated kinase (ERK), NOTCH1, and p-STAT3 in patients with MF. METHODS: In all, 54 skin biopsy specimens (21 tumors, 30 plaques, and 3 folliculotropic MF) from 50 patients with MF were analyzed immunohistochemically for p-mTOR, its upstream p-AKT, its downstream effectors p-p70S6K and p-4E-BP1, and for p-ERK1/2, NOTCH1, and p-STAT3. RESULTS: p-mTOR was coexpressed with p-p70S6K in 67.3% of lesions, but coexpression with other molecules was less common. p-p70S6K and marginally NOTCH1 displayed higher H-scores in tumors than in plaques. Significant correlations were recorded between p-ERK and p-4E-BP1, as well as between NOTCH1 and p-p70S6K or p-4E-BP1. NOTCH1, p-4E-BP1, and p-p70S6K expression were associated with advanced stage. In survival analysis simultaneous overexpression of p-AKT and p-p70S6K, along with p-4E-BP1 positivity, adversely affected cancer-specific, disease-free, and progression-free survival in advanced-stage cases. LIMITATIONS: A limitation may be the small number of cases included in our investigation, precluding multivariate survival analysis. CONCLUSIONS: Activation of AKT/mTOR pathway in MF appears to be correlated with NOTCH1, p-ERK, and p-STAT3 and is implicated in the acquisition of a more aggressive phenotype. The combination of p-AKT, p-p70S6K, and p-4E-BP1 emerges as a significant potential prognostic marker in patients with advanced stage.

The role of bone marrow biopsy examination at diagnosis of chronic lymphocytic leukemia: a reappraisal.

According to the International Workshop on Chronic Lymphocytic Leukemia/National Institutes of Health (iwCLL/NIH) guidelines for the diagnosis and treatment of chronic lymphocytic leukemia (CLL), bone marrow biopsy (BMB) is not required at diagnosis, however recommended before initiating treatment. That notwithstanding, histopathological examination of the BMB has the potential to provide important information of both clinical and biological significance. Here we attempt a reappraisal of the role of BMB examination in the modern diagnostic work-up of patients with CLL, based on both the literature and our accumulated experience from the systematic and multiparametric evaluation of a large series of BMB samples taken at diagnosis of CLL. Overall, we argue that the study of BMB offers important information not only for diagnostic purposes but also for elucidating CLL pathobiology.

Treatment of splenic marginal zone lymphoma with rituximab monotherapy: progress report and comparison with splenectomy.

BACKGROUND: Treatment of splenic marginal zone lymphoma (SMZL) patients is not standardized. Recent data suggest that rituximab is highly effective and could be considered as initial therapy. AIM: To assess the efficacy of rituximab monotherapy in a large series of patients with SMZL and compare these results with splenectomy results. METHODS: The studied population included 85 patients. Fifty-eight received rituximab at a dose of 375 mg/m2 per week for 6 weeks as induction followed by maintenance at the same dose every 2 months for 1-2 years, whereas 27 patients were treated using splenectomy only. RESULTS: The overall response rate to rituximab 2 months after the end of induction was 95% (complete response [CR], 45%; unconfirmed CR, 26%; partial response, 24%). The median times to hematologic and clinical response were 2 weeks and 3 weeks, respectively. Forty-three of 55 patients already completed the maintenance phase: 28 sustained their initial response, 14 improved their response, and one progressed. Eighty-five percent of splenectomized patients responded, and two were treated with rituximab as consolidation after splenectomy and achieved a CR. The 5-year overall and progression-free survival (PFS) rates for rituximab-treated and splenectomized patients were 92% and 77% (p = .09) and 73% and 58% (p = .06), respectively. Furthermore, maintenance therapy with rituximab resulted in a longer duration of response (at 5 years, PFS was 84% for patients receiving maintenance and 36% for patients without maintenance, p <.0001). CONCLUSIONS: Rituximab is a very effective and well-tolerated therapy and may be substituted for splenectomy as the first-line treatment of choice for patients with SMZL.

Bone marrow histopathology in the diagnostic evaluation of splenic marginal-zone and splenic diffuse red pulp small B-cell lymphoma: a reliable substitute for spleen histopathology?

Primary splenic small B-cell lymphomas mostly comprise the distinct entity of splenic marginal-zone lymphoma (SMZL) and the provisional category of splenic lymphoma/leukemia unclassifiable, mainly represented by the hairy cell leukemia variant and splenic diffuse red pulp small B-cell lymphoma (SDRL). Until recently, histopathologic examination of splenectomy specimens was considered mandatory for the diagnosis of SMZL. However, nowadays, mainly because of advances in chemoimmunotherapy, splenectomy is performed much less frequently. We evaluated the diagnostic efficacy of bone marrow biopsy (BMB) histopathology in the diagnostic approach toward SMZL and SDRL and tested whether it may serve as a substitute for spleen histopathology in the differential diagnosis between these 2 entities. To this end, we conducted a paired assessment of BMB and spleen diagnostic samples from 46 cases with a diagnosis of SMZL (n=32) or SDRL (n=14) based on spleen histopathology. We demonstrate that detailed immunohistopathologic BMB evaluation offers adequate evidence for the confirmation of these entities and their differential diagnosis from other small B-cell lymphoma histotypes. Notably, the immunophenotypical profile of SMZL and SDRL was identical in both BMB and spleen specimens for 21 evaluated markers. Paired assessment of BMB and spleen specimens did not identify discriminating patterns of BMB infiltration, cytology, and/or immunohistology between SMZL and SDRL. Accordingly, bone marrow histopathology contributes significantly in confirming the diagnosis of SMZL and SDRL. However, presently it is not possible to distinguish SMZL from SDRL on the basis of BMB evaluation alone; hence, histopathologic examination of the spleen remains the "gold standard" approach.

Molecular subsets of mantle cell lymphoma defined by the IGHV mutational status and SOX11 expression have distinct biologic and clinical features.

Mantle cell lymphoma (MCL) is a heterogeneous disease with most patients following an aggressive clinical course, whereas others having an indolent behavior. We conducted an integrative and multidisciplinary analysis of 177 MCL to determine whether the immunogenetic features of the clonotypic B-cell receptors (BcR) may identify different subsets of tumors. Truly unmutated (100% identity) IGHV genes were found in 24% cases, 40% were minimally/borderline mutated (99.9%-97%), 19% significantly mutated (96.9%-95%), and 17% hypermutated (<95%). Tumors with high or low mutational load used different IGHV genes, and their gene expression profiles were also different for several gene pathways. A gene set enrichment analysis showed that MCL with high and low IGHV mutations were enriched in memory and naive B-cell signatures, respectively. Furthermore, the highly mutated tumors had less genomic complexity, were preferentially SOX11-negative, and showed more frequent nonnodal disease. The best cut-off of germline identity of IGHV genes to predict survival was 97%. Patients with high and low mutational load had significant different outcome with 5-year overall survival (OS) of 59% and 40%, respectively (P = 0.004). Nodal presentation and SOX11 expression also predicted for poor OS. In a multivariate analysis, IGHV gene status and SOX11 expression were independent risk factors. In conclusion, these observations suggest the idea that MCL with mutated IGHV, SOX11-negativity, and nonnodal presentation correspond to a subtype of the disease with more indolent behavior.