Non-MALT marginal zone lymphoma

Identification of a Splenic Marginal Zone Lymphoma Signature: Preliminary Findings With Diagnostic Potential

Splenic marginal zone lymphoma (SMZL) is a rare, indolent non-Hodgkin's lymphoma that affects 0. 13 per 100,000 persons annually. Overall survival of SMZL is estimated to reach 8-11 years in most cases, but up to 30% of SMZL cases develop aggressive presentations resulting in greatly diminished time of survival. SMZL presents with a very heterogeneous molecular profile, making diagnosis problematic, and accurate prognosis even less likely. The study herein has identified a potential diagnostic gene expression signature with highly specific predictive utility, coined the SMZL-specific Gene Expression Signature (SSGES). Additionally, five of the most impactful markers identified within the SSGES were selected for a five-protein panel, for further evaluation among control and SMZL patient samples. These markers included EME2, ERCC5, SETBP1, USP24, and ZBTB32. When compared with control spleen and other B-cell lymphoma subtypes, significantly higher expression was noticed in SMZL samples when stained for EME2 and USP24. Additionally, ERCC5, SETBP1, USP24, and ZBTB32 staining displayed indications of prognostic value for SMZL patients. Delineation of the SSGES offers a unique SMZL signature that could provide diagnostic utility for a malignancy that has historically been difficult to identify, and the five-marker protein panel provides additional support for such findings. These results should be further investigated and validated in subsequent molecular investigations of SMZL so it may be potentially incorporated into standard oncology practice for improving the understanding and outlook for SMZL patients.

Marginal zone B-cell lymphoma: lessons from Western and Eastern diagnostic approaches

Marginal zone B-cell lymphomas (MZLs) are a group of clinically indolent B-cell lymphomas postulated to derive from memory B lymphocytes in the 'marginal zone' of secondary lymphoid tissue. Today, MZL is recognised as a nosological umbrella term encompassing distinct entities with some shared phenotypic and genotypic features, including extranodal marginal zone B-cell lymphoma (EMZL) or mucosa-associated lymphoid tissue (MALT) lymphoma, splenic MZL, and nodal MZL, accounting for approximately 70%, 20%, and 10% of MZLs, respectively. These lymphomas share some phenotypic and genotypic features and have some variants and related provisional diseases, but are different in regards to their clinical and molecular characteristics. In addition, they are frequently associated with chronic antigenic stimulation represented either by infectious agents, particularly bacteria and viruses, or autoimmune diseases as exemplified by Sjögren syndrome, Hashimoto thyroiditis, and newly recognised IgG4-related disease. Furthermore, several chromosomal translocations have been identified in EMZL. In this review, we will focus on the updated histopathological criteria and the main problems with differential diagnoses in order to aid the diagnostic approach in our routine practice.

The NOTCH Pathway and Its Mutations in Mature B Cell Malignancies

The systematic application of next-generation sequencing to large cohorts of oncologic samples has opened a Pandora's box full of known and novel genetic lesions implicated in different steps of cancer development and progression. Narrowing down to B cell malignancies, many previously unrecognized genes emerged as recurrently mutated. The challenge now is to determine how the mutation in a given gene affects the biology of the disease, paving the way to functional genomics studies. Mutations in NOTCH family members are shared by several disorders of the B series, even if with variable frequencies and mutational patterns. In silico predictions, revealed that mutations occurring in NOTCH receptors, despite being qualitatively different, may have similar effects on protein processing, ultimately leading to enhanced pathway activation. The discovery of mutations occurring also in downstream players, either potentiating positive signals or compromising negative regulators, indicates that multiple mechanisms in neoplastic B cells concur to activate NOTCH pathway. These findings are supported by results obtained in chronic lymphocytic leukemia and splenic marginal zone B cell lymphoma where deregulation of NOTCH signaling has been functionally characterized. The emerging picture confirms that NOTCH signaling is finely tuned in cell- and microenvironment-dependent ways. In B cell malignancies, it contributes to the regulation of proliferation, survival and migration. However, deeper biological studies are needed to pinpoint the contribution of NOTCH in the hierarchy of events driving B cells transformation, keeping in mind its role in normal B cells development. Because of its relevance in leukemia and lymphoma biology, the NOTCH pathway might represent an appealing therapeutic target: the next few years will tell whether this potential will be fulfilled.

Canine nodal marginal zone lymphoma: Descriptive insight into the biological behaviour

Canine nodal marginal zone lymphoma (nMZL) is classified as an indolent lymphoma. Such lymphomas are typified by low mitotic rate and slow clinical progression. While the clinical behaviour of canine splenic MZL has been described, characterized by an indolent course and a good prognosis following splenectomy, there are no studies specifically describing nMZL. The aim of this study was to describe the clinical features of and outcome for canine nMZL. Dogs with histologically confirmed nMZL undergoing a complete staging work-up (including blood analysis, flow cytometry [FC] on lymph node [LN], peripheral blood and bone marrow, imaging, histology and immunohistochemistry on a surgically removed peripheral LN) were retrospectively enrolled. Treatment consisted of chemotherapy or chemo-immunotherapy. Endpoints were response rate (RR), time to progression (TTP) and lymphoma-specific survival (LSS). A total of 35 cases were enrolled. At diagnosis, all dogs showed generalized lymphadenopathy. One-third was systemically unwell. All dogs had stage V disease; one-third also had extranodal involvement. The LN population was mainly composed of medium-sized CD21+ cells with scant resident normal lymphocytes. Histology revealed diffuse LN involvement, referring to "late-stage" MZL. Median TTP and LSS were 149 and 259 days, respectively. Increased LDH activity and substage b were significantly associated with a shorter LSS. Dogs with nMZL may show generalized lymphadenopathy and an advanced disease stage. Overall, the outcome is poor, despite the "indolent" designation. The best treatment option still needs to be defined.

The genetics of nodal marginal zone lymphoma

Nodal marginal zone lymphoma (NMZL) is a rare, indolent B-cell tumor that is distinguished from splenic marginal zone lymphoma (SMZL) by the different pattern of dissemination. NMZL still lacks distinct markers and remains orphan of specific cancer gene lesions. By combining whole-exome sequencing, targeted sequencing of tumor-related genes, whole-transcriptome sequencing, and high-resolution single nucleotide polymorphism array analysis, we aimed at disclosing the pathways that are molecularly deregulated in NMZL and we compare the molecular profile of NMZL with that of SMZL. These analyses identified a distinctive pattern of nonsilent somatic lesions in NMZL. In 35 NMZL patients, 41 genes were found recurrently affected in ≥3 (9%) cases, including highly prevalent molecular lesions of MLL2 (also known as KMT2D; 34%), PTPRD (20%), NOTCH2 (20%), and KLF2 (17%). Mutations of PTPRD, a receptor-type protein tyrosine phosphatase regulating cell growth, were enriched in NMZL across mature B-cell tumors, functionally caused the loss of the phosphatase activity of PTPRD, and were associated with cell-cycle transcriptional program deregulation and increased proliferation index in NMZL. Although NMZL shared with SMZL a common mutation profile, NMZL harbored PTPRD lesions that were otherwise absent in SMZL. Collectively, these findings provide new insights into the genetics of NMZL, identify PTPRD lesions as a novel marker for this lymphoma across mature B-cell tumors, and support the distinction of NMZL as an independent clinicopathologic entity within the current lymphoma classification.

Medical history, lifestyle, family history, and occupational risk factors for marginal zone lymphoma: the InterLymph Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Marginal zone lymphoma (MZL), comprised of nodal, extranodal, and splenic subtypes, accounts for 5%-10% of non-Hodgkin lymphoma cases. A detailed evaluation of the independent effects of risk factors for MZL and its subtypes has not been conducted.

METHODS

Data were pooled from 1052 MZL cases (extranodal [EMZL] = 633, nodal [NMZL] = 157, splenic [SMZL] = 140) and 13766 controls from 12 case-control studies. Adjusted unconditional logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Novel findings for MZL subtypes include increased risk for B-cell activating autoimmune conditions (EMZL OR = 6.40, 95% CI = 4.24 to 9.68; NMZL OR = 7.80, 95% CI = 3.32 to 18.33; SMZL OR = 4.25, 95% CI = 1.49 to 12.14), hepatitis C virus seropositivity (EMZL OR = 5.29, 95% CI = 2.48 to 11.28), self-reported peptic ulcers (EMZL OR = 1.83, 95% CI = 1.35 to 2.49), asthma without other atopy (SMZL OR = 2.28, 95% CI = 1.23 to 4.23), family history of hematologic cancer (EMZL OR = 1.90, 95% CI = 1.37 to 2.62) and of non-Hodgkin lymphoma (NMZL OR = 2.82, 95% CI = 1.33 to 5.98), permanent hairdye use (SMZL OR = 6.59, 95% CI = 1.54 to 28.17), and occupation as a metalworker (NMZL OR = 3.56, 95% CI = 1.67 to 7.58). Reduced risks were observed with consumption of any alcohol (EMZL fourth quartile OR = 0.48, 95% CI = 0.28 to 0.82) and lower consumption of wine (NMZL first to third quartile ORs < 0.45) compared with nondrinkers, and occupation as a teacher (EMZL OR = 0.58, 95% CI = 0.37 to 0.88).

CONCLUSION

Our results provide new data suggesting etiologic heterogeneity across MZL subtypes although a common risk of MZL associated with B-cell activating autoimmune conditions was found.

Absence of TCL1A expression is a useful diagnostic feature in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a low-grade lymphoma showing a rather nonspecific immunophenotype. Gene expression profiling studies suggested that TCL1A could be a marker of SMZL, but reported data are conflicting. We evaluated TCL1A expression in a series of spleen and bone marrow samples involved by SMZL and correlated the findings with other immunophenotypical, morphological, and clinical data. In addition, we evaluated the expression of TCL1A in a series of spleens and lymph nodes involved by lymphomas that might mimic SMZL (13 nodal marginal zone lymphomas (NMZL), 39 follicular lymphomas (FL), 30 B-cell chronic lymphocytic leukemias (B-CLL), 31 mantle cell lymphomas (MCL), 1 lymphoplasmacytic lymphoma) and 15 bone marrow specimens involving hairy cell leukemia (HCL). TCL1A staining was negative in 24/31 cases of SMZL (77 %); 27/31 MCL and all B-CLL were positive for TCL1A; 32/34 cases of nodal FL (96 %) and all five splenic FL were positive for TCL1A, although at a lower intensity. Eight of 13 NMZL were positive for TCL1A, often showing a heterogeneous staining pattern. All HCL samples were strongly positive for TCL1A. No correlation was found between the pattern of splenic infiltration, TCL1A expression, and the clinical course. TCL1A-positive SMZL showed a higher rate of DBA44 staining compared to the negative ones, and this difference was statistically significant (Fisher test, single-tailed, p = 0.0397). Our data support the use of TCL1A in the panel of diagnostic markers used in the differential diagnosis of splenic low-grade B-cell lymphoma; a possible prognostic value, however, needs a larger series to be established.