Time to Be Launched 1 auXiliary Risk strat1fier in marginal zone lymphoma transformation: TBL1XR1

The genetic profile of lymphomas has an increasing role in diagnosis, prognostication, and therapeutic decision making. In this issue of Cancer, Li and colleagues provide insights into the genomic landscape of high‐grade transformation of marginal zone lymphoma compared with both indolent marginal zone lymphoma and de novo diffuse large B‐cell lymphoma.

The role of baseline 2-[18 F]-FDG-PET/CT metrics and radiomics features in predicting primary gastric lymphoma diagnosis

Diffuse Large B-Cell Lymphomas (DLCBL) and mucosa-associated lymphoid tissue (MALT) are the two most common primary gastric lymphomas (PGLs), but have strongly different features. DLBCL is more aggressive, is frequently diagnosed at an advanced stage and has a poorer prognosis. The aim of this retrospective study was to explore the role of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18 F]-FDG-PET/CT) and radiomics features (RFs) in predicting the final diagnosis of patients with PGLs. Ninety-one patients with newly diagnosed PGLs who underwent pre-treatment 2-[18 F]-FDG-PET/CT were included. PET images were qualitatively and semi-quantitatively analyzed by deriving maximum standardized uptake value body weight (SUVbw), maximum standardized uptake value lean body mass (SUVlbm), maximum standardized uptake value body surface area (SUVbsa), lesion to liver SUVmax ratio (L-L SUV R), lesion to blood-pool SUVmax ratio (L-BP SUV R), metabolic tumor volume (gMTV) and total lesion glycolysis of gastric lesion (gTLG), total MTV (tMTV), TLG, and first-order RFs (histogram-related and shape related). Receiver-operating characteristic (ROC) curve analyses were performed to determine the differential diagnostic values of PET parameters. The final diagnosis was DLBCL in 54 (59%) cases and MALT in 37 cases (41%). PGLs showed FDG avidity in 83 cases (90%), 54/54 of DLBCL and 29/37 of MALT. All PET/CT metabolic features, such as stage of disease and tumor size, were significantly higher in DLBCL than MALT; while the presence of H. Pylori infection was more common in MALT. At univariate analysis, all PET/CT metrics were significantly higher in DLBCL than MALT lymphomas, while among RFs only Shape volume_vx and Shape sphericity showed a significant difference between the two groups. In conclusion we demonstrated that 2-[18 F]-FDG-PET/CT parameters can potentially discriminate between DLBCL and MALT lymphomas with high accuracy. Among first-order RFs, only Shape volume_vx and Shape sphericity helped in the differential diagnosis.

The application of a multidisciplinary approach in the diagnosis of Castleman disease and Castleman-like lymphadenopathies: A 20-year retrospective analysis of clinical and pathological features

BACKGROUND

Castleman disease (CD) comprises a group of rare and heterogeneous haematological disorders, including unicentric (UCD) and multicentric (MCD) forms, the latter further subdivided into HHV8-MCD, POEMS-MCD and idiopathic-MCD (iMCD). However, according to the Castleman Disease Collaborative Network guidelines, the diagnosis of CD can only be achieved through collaboration between clinicians and pathologists.

METHODS

We applied these clinical and pathological criteria and implement with clonality testing to a retrospective cohort of 48 adult and paediatric Italian patients diagnosed with reactive lymphadenitis with CD-like histological features.

RESULTS

We confirmed the diagnosis of CD in 60% (29/48) of the cases, including 12 (41%) UCD and 17 (59%; five HHV8-MCD, three POEMS-MCD and nine iMCD) MCD. Of the remaining 19 cases (40%) with multiple lymphadenopathy, 5 (26%) were classified as autoimmune diseases, 1 (5%) as autoimmune lymphoproliferative disorder, 1 (5%) as IgG4-related disease, 11 (83%) as reactive lymphadenitis and 1 (5%) as nodal marginal zone lymphoma.

CONCLUSIONS

Our study emphasizes the importance of the multidisciplinary approach to reactive lymphadenitis with CD-like features in order to achieve a definitive diagnosis and choose the appropriate treatment.

The first autopsy case of Epstein-Barr virus-positive marginal zone lymphoma that deteriorated after COVID-19 vaccination

This is the first autopsy case of Epstein-Barr virus-positive marginal zone lymphoma (EBV + MZL) with an other iatrogenic immunodeficiency-associated lymphoproliferative disorders (LPD) (methotrexate [MTX]-associated LPD) that deteriorated after the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. This case had a unique immunophenotype. A 71-year-old female patient with rheumatoid arthritis receiving MTX presented with fatigue 1 week after the SARS-CoV-2 vaccination. She was hospitalized due to hepatorenal dysfunction and pancytopenia. Computed tomography revealed systemic lymphadenopathy. Her physical condition deteriorated, and the patient died. The autopsy revealed systemic lymphadenopathy comprising medium-sized atypical lymphocytes and scattered Hodgkin/Reed-Sternberg (H/RS)-like cells. An immunohistochemical examination showed that atypical lymphocytes were positive for CD79a and MUM-1 and some were positive for CD20 and IRTA-1. H/RS-like cells were immunoreactive for CD30 and CD15 and ringed by T cells. Both cell types were positive for EBV-encoded small RNA. The majority of H/RS-like cells were positive for CD20, whereas a small number of CD3-positive cells were admixed. We herein presented the first autopsy case of EBV + MZL that deteriorated after the SARS-CoV-2 vaccination.

Gastric microbiota in patients with gastric MALT lymphoma according to Helicobacter pylori infection

BACKGROUND

Gastric Mucosa Associated Lymphoid Tissue lymphoma (GML) development is triggered by Helicobacter pylori (H. pylori) infection. Little is known about the impact of H. pylori infection on gastric microbiota.

METHODS

The gastric microbiota was retrospectively investigated using 16S rRNA gene sequencing in 32 patients with untreated GML (10 H. pylori-positive and 22 H. pylori-negative), 23 with remitted and 18 refractory GML and 35 controls. Differences in microbial diversity, bacterial composition and taxonomic repartition were assessed.

RESULTS

There was no change in diversity and bacterial composition between GML and control patients taking into account H. pylori status. Differential taxa analysis identified specific changes associated with H. pylori-negative GML: the abundances of Actinobacillus, Lactobacillus and Chryseobacterium were increased while the abundances of Veillonella, Atopobium, Leptotrichia, Catonella, Filifactor and Escherichia_Shigella were increased in control patients. In patients with remitted GML, the genera Haemophilus and Moraxella were significantly more abundant than in refractory patients, while Atopobium and Actinomyces were significantly more abundant in refractory patients.

CONCLUSION

Detailed analysis of the gastric microbiota revealed significant changes in the bacterial composition of the gastric mucosa in patients with GML that may have a role in gastric lymphomagenesis but not any new pathobionts.

Indolent B-cell lymphoma with t(14;19) investigated from a molecular perspective

T(14;19) is an unusual but distinct genomic alteration reported in low-grade B-cell lymphomas. This structural rearrangement places BCL3 in juxtaposition with IGH inducing proliferation and has been found in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), marginal zone lymphoma (MZL), and other low-grade B-cell lymphomas. While there are some case series describing this in the context of other cytogenetic alterations, there are limited clinical cases examined from a molecular perspective. We herein describe a case of a low-grade B-cell lymphoma with t(14;19) resulting in IGH::BCL3 fusion on which we performed whole exome sequencing to investigate genetic variants that could contribute to its pathogenesis. We found pathogenic alterations including a variant in CXCR4 which has been shown to be recurrently mutated in different low-grade B-cell lymphomas including lymphoplasmacytic lymphoma (LPL) and MZL. We describe this interesting case in the context of its genomic findings and how it contributes to the literature as a whole.

Multipurpose ultrasonographic characteristics of primary uveal MALT lymphoma

PURPOSE

To investigate the ultrasonographic features in patients with primary uveal mucosa-associated lymphoid tissue (MALT) lymphoma.

METHODS

Medical records of 12 patients (13 eyes) diagnosed with primary uveal MALT lymphoma between September 2014 and September 2021 were retrospectively reviewed. Ultrasonography, B-scan ultrasonography, color Doppler flow imaging, and ultrasound biomicroscopy findings were retrieved from the medical records.

RESULTS

Mean age of the included patients was 59.4 ± 8.6 years. Typical ultrasonographic features of the choroidal infiltrates were flat, diffuse, and thickened, with low and homogenous internal reflectivity and with rich arterial blood flow from posterior ciliary arterioles. The mean thickness of the choroidal infiltrates was 1.34 ± 0.68 mm (n = 13). Most of the affected eyes had posterior episcleral extensions, with a mean thickness of 1.66 ± 1.21 mm (n = 12). Typical crescent-like posterior episcleral extensions were detected in nine eyes (69.2%). In six eyes, the blood flow from the choroidal infiltrates communicated with the episcleral extensions. In the ciliary body, the mean thickness of the infiltrates was 1.08 ± 0.43 mm (n = 9), and seven eyes (77.8%) had 360° ring-like infiltrations. The initial best-corrected visual acuity (BCVA) was significantly correlated with the final BCVA after treatment (p < 0.001).

CONCLUSION

Multipurpose ultrasonographic imaging revealed the unique characteristics of the primary uveal MALT lymphoma and is helpful in the diagnosis of this rare disease.

Lumbar radiculopathy secondary to primary spinal dural diffuse large B-cell lymphoma

Lymphoma of a dural genesis is a distinct variant of primary central nervous system lymphoma and is rare. It putatively has a more benign clinical course. Cranial primary dural lymphoma is more often marginal zone B-cell lymphoma, whereas spinal primary dural lymphoma is most commonly diffuse large B-cell lymphoma.We report a male patient who presented with subacute progressive radiculopathy due to a compressive infiltrative lumbosacral spinal lesion. This was determined to be primary dural diffuse large B-cell lymphoma. The radiology, therapeutic considerations and differentiating biological characteristics of primary dural lymphoma, differ from other primary central nervous system lymphomas.Primary dural lymphoma is under-represented in the medical literature. It has unique clinical characteristics. The optimal treatment algorithm remains undefined, but there is some evidence suggesting a benefit of surgical cytoreductive therapy in the first instance, and low-dose radiotherapy may be an effective adjuvant therapy in addition to chemotherapeutic and immunotherapeutic agents.

Direct intranodal tonsil vaccination with modified vaccinia Ankara vaccine protects macaques from highly pathogenic SIVmac251

Human immunodeficiency virus (HIV) is a mucosally transmitted virus that causes immunodeficiency and AIDS. Developing efficacious vaccines to prevent infection is essential to control the epidemic. Protecting the vaginal and rectal mucosa, the primary routes of HIV entry has been a challenge given the significant compartmentalization between the mucosal and peripheral immune systems. We hypothesized that direct intranodal vaccination of mucosa associated lymphoid tissue (MALT) such as the readily accessible palatine tonsils could overcome this compartmentalization. Here we show that rhesus macaques primed with plasmid DNA encoding SIVmac251-env and gag genes followed by an intranodal tonsil MALT boost with MVA encoding the same genes protects from a repeated low dose intrarectal challenge with highly pathogenic SIVmac251; 43% (3/7) of vaccinated macaques remained uninfected after 9 challenges as compared to the unvaccinated control (0/6) animals. One vaccinated animal remained free of infection even after 22 challenges. Vaccination was associated with a ~2 log decrease in acute viremia that inversely correlated with anamnestic immune responses. Our results suggest that a combination of systemic and intranodal tonsil MALT vaccination could induce robust adaptive and innate immune responses leading to protection from mucosal infection with highly pathogenic HIV and rapidly control viral breakthroughs.

Concurrent Presentation of Mycosis Fungoides and Primary Cutaneous Marginal Zone LPD: Clinicopathological Study of 4 Cases and Literature Review

BACKGROUND

Mycosis fungoides is rarely associated to B-cell malignancies, and the few reported cases are mainly internal lymphomas involving secondarily the skin (ie, chronic lymphocytic leukemia).

OBJECTIVES

The aim of our study is to describe the clinical and histopathological features of 4 patients presenting with 2 concurrent primary cutaneous lymphomas and review the pertinent literature.

METHODS

We identified 4 cases of concurrent primary cutaneous lymphomas in our institutions. An extracutaneous lymphoma was ruled out on the basis of a complete work out. We performed a PubMed search to identify reported cases of primary cutaneous composite or concurrent lymphomas.

RESULTS

Eleven cases of primary cutaneous concurrent lymphomas have been described in the literature. Counting all together (our cases and the cases previously described in the literature), mycosis fungoides was the most frequent primary cutaneous T-cell lymphoma (TCL) (13/15), followed by 1 case of peripheral TCL-NOS and 1 case of subcutaneous panniculitis-like TCL. Regarding the associated primary cutaneous B-cell lymphomas, 8/15 cases consisted of low-grade B-cell lymphomas [that is, 5 marginal zone lymphoma (in the most recent classification reclassified as marginal zone lymphoproliferative disorder, MZLD, 2 follicular-center B-cell lymphoma (primary cutaneous follicle-center lymphoma) and 1 low-grade NOS B-cell lymphoma]; 4/15 were associated to Epstein-Barr virus; 1 case consisted of a methotrexate-associated lymphoproliferative disease, and 2 cases consisted of primary cutaneous diffuse large B-cell lymphoma-leg type.

CONCLUSIONS

Primary cutaneous concurrent lymphomas are exceptional. Clinicopathological correlation and a complete workout to reach the correct diagnosis may guide the appropriate treatment in each case.

Application of modified Matutes score containing CD200 in diagnosis of chronic lymphocytic leukemia

OBJECTIVES

Immunophenotyping technique is a powerful tool for the diagnosis and differential diagnosis of chronic lymphocytic leukemia (CLL) and other B-cell chronic lymphoproliferative diseases (B-CLPD). CD200 is strongly expressed in CLL. This study aims to analyze the clinical value of modified Matutes score (MMS) containing CD200 in the diagnosis of CLL.

METHODS

We retrospectively analyzed 103 B-CLPD patients diagnosed from January 2020 to July 2021, including 64 CLL patients, 11 follicular lymphoma (FL) patients, 14 mantle cell lymphoma (MCL) patients, 6 marginal zone lymphoma (MZL) patients, 1 hairy cell leukemia (HCL) patient, and 7 lymphoplasmic lymphoma/Waldenstrom macroglobulinemia (LPL/WM) patients. The expression of CD markers between the CLL group and the non-CLL group was compared, and the sensitivity, specificity, and clinical consistency of MMS and Royal Marsden Hospital (RMH) immunophenotyping score system were analyzed.

RESULTS

There were significant differences in the expressions of CD5, CD23, FMC7, CD22, CD79b, CD200, and sIg between the CLL group and the non-CLL group (χ2 values were 37.42, 54.98, 30.71, 11.67, 55.26, 68.48, and 17.88, respectively, all P<0.01). When the RMH immunophenotyping score≥4, the sensitivity was 79.7%, and the specificity was 100%. When the MMS≥3, the sensitivity was 95.3%, and the specificity was 100%. The Kappa coefficient of RMH immunophenotyping system was 0.677, and the Kappa coefficient of MMS system was 0.860.

CONCLUSIONS

The MMS system containing CD200 has better sensitivity and same specificity compared with RMH immunophenotyping system, and MMS system may be more useful in the diagnosis of CLL.

The role of the CBM complex in allergic inflammation and disease

The caspase activation and recruitment domain-coiled-coil (CARD-CC) family of proteins-CARD9, CARD10, CARD11, and CARD14-is collectively expressed across nearly all tissues of the body and is a crucial mediator of immunologic signaling as part of the CARD-B-cell lymphoma/leukemia 10-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (CBM) complex. Dysfunction or dysregulation of CBM proteins has been linked to numerous clinical manifestations known as "CBM-opathies." The CBM-opathy spectrum encompasses diseases ranging from mucocutaneous fungal infections and psoriasis to combined immunodeficiency and lymphoproliferative diseases; however, there is accumulating evidence that the CARD-CC family members also contribute to the pathogenesis and progression of allergic inflammation and allergic diseases. Here, we review the 4 CARD-CC paralogs, as well as B-cell lymphoma/leukemia 10 and mucosa-associated lymphoid tissue lymphoma translocation protein 1, and their individual and collective roles in the pathogenesis and progression of allergic inflammation and 4 major allergic diseases (allergic asthma, atopic dermatitis, food allergy, and allergic rhinitis).

Clinicopathological features and individualized treatment of kidney involvement in B-cell lymphoproliferative disorder

Background

Due to the various clinical and pathological manifestations of kidney involvement in lymphoproliferative disorder (LPD), the whole spectrum of kidney disease in LPD is still unclear, and data on kidney prognosis is scarce.

Methods

We retrospectively reviewed the renal pathology profiles from January 2010 to December 2021, and 28 patients with B-cell LPD combined with intact renal biopsy data were included.

Results

There were 20 men and eight women aging 41 to 79 years at the time of renal biopsy (median age 62 years). According to hematological diagnosis, patients were classified into four groups: chronic lymphocytic leukemia (CLL) (group1, n=7), Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) (group 2, n=8; WM, n=6; LPL, n=2), Other non-Hodgkin’s lymphomas (NHL) (group3, n=7; diffuse large B-cell lymphoma (DLBCL), n=2; mucosa-associated lymphoid tissue (MALT) lymphoma, n=4; Low grade B-cell lymphoma, n=1), and monoclonal gammopathy of undetermined significance/monoclonal gammopathy of renal significance (MGUS/MGRS) (group 4, n=6). Median serum creatinine (Scr) level was 129 (range,59-956) umol/L. Eight patients (29%) were presented with acute kidney injury (AKI), and five patients (18%) required hemodialysis upon admission. Twenty-three patients (82%) presented with proteinuria (median protein excretion, 2.14 g/d), 11(39%) of whom had the nephrotic syndrome. Interstitial malignant infiltration was the most frequent renal lesion (n=6). Eight patients underwent immunohistochemistry of renal tissues, of which three patients (CLL, n=1; LPL, n=1; WM, n=1) had confirmed lymphoma infiltrates, and the infiltrating cells in the remaining five patients (CLL, n=1; MALT lymphoma, n=2; MGUS, n=2) were considered unrelated to lymphoma. The most common glomerular diseases were renal amyloidosis (n=4) and membranous nephropathy (n=4). Only 20 patients were treated, 13 of whom were treated with rituximab separately or in combination. The median follow-up time was 11 months. Of these, six had achieved hematological response, complete response in five cases. Eight had achieved renal response. At the end-of-study visit, four patients died and two progressed to end stage kidney disease (ESKD).

Conclusion

In conclusion, the clinicopathological spectrum of renal involvement in BLPD is diverse. Renal biopsy and immunohistochemistry are required for early diagnosis and prognostic assessment.

Cecal MALT lymphoma: a challenging diagnosis

A 76-year-old female with a medical history of diabetes, arterial hypertension and dyslipidemia sought medical assistance due to left flank abdominal pain, fatigue and anorexia over the previous month. Laboratory analyses were normal and the computed tomography (CT) scan showed colonic diverticulosis and mesenteric panniculitis.

The MAGNOLIA Trial: Zanubrutinib, a Next-Generation Bruton Tyrosine Kinase Inhibitor, Demonstrates Safety and Efficacy in Relapsed/Refractory Marginal Zone Lymphoma

PURPOSE

Marginal zone lymphoma (MZL) is an uncommon non-Hodgkin lymphoma with malignant cells that exhibit a consistent dependency on B-cell receptor signaling. We evaluated the efficacy and safety of zanubrutinib, a next-generation selective Bruton tyrosine kinase inhibitor, in patients with relapsed/refractory (R/R) MZL.

PATIENTS AND METHODS

Patients with R/R MZL were enrolled in the phase II MAGNOLIA (BGB-3111-214) study. The primary endpoint was overall response rate (ORR) as determined by an independent review committee (IRC) based on the Lugano 2014 classification.

RESULTS

Sixty-eight patients were enrolled. After a median follow-up of 15.7 months (range, 1.6 to 21.9 months), the IRC-assessed ORR was 68.2% and complete response (CR) was 25.8%. The ORR by investigator assessment was 74.2%, and the CR rate was 25.8%. The median duration of response (DOR) and median progression-free survival (PFS) by independent review was not reached. The IRC-assessed DOR rate at 12 months was 93.0%, and IRC-assessed PFS rate was 82.5% at both 12 and 15 months. Treatment was well tolerated with the majority of adverse events (AE) being grade 1 or 2. The most common AEs were diarrhea (22.1%), contusion (20.6%), and constipation (14.7%). Atrial fibrillation/flutter was reported in 2 patients; 1 patient had grade 3 hypertension. No patient experienced major hemorrhage. In total, 4 patients discontinued treatment due to AEs, none of which were considered treatment-related by the investigators.

CONCLUSIONS

Zanubrutinib demonstrated high ORR and CR rate with durable disease control and a favorable safety profile in patients with R/R MZL.

A federated AI strategy for the classification of patients with Mucosa Associated Lymphoma Tissue (MALT) lymphoma across multiple harmonized cohorts

Mucosa Associated Lymphoma Tissue (MALT) type is an extremely rare type of lymphoma which occurs in less than 3% of patients with primary Sjögren's Syndrome (pSS). No reported studies so far have been able to investigate risk factors for MALT development across multiple cohort databases with sufficient statistical power. Here, we present a generalized, federated AI (artificial intelligence) strategy which enables the training of AI algorithms across multiple harmonized databases. A case study is conducted towards the development of MALT classification models across 17 databases on pSS. Advanced AI algorithms were developed, including federated Multinomial Naïve Bayes (FMNB), federated gradient boosting trees (FGBT), FGBT with dropouts (FDART), and the federated Multilayer Perceptron (FMLP). The FDART with dropout rate 0.3 achieved the best performance with sensitivity 0.812, and specificity 0.829, yielding 8 biomarkers as prominent for MALT development.

How I treat MALT lymphoma: 'a subjective interpretation of the gospel according to Isaacson….'

Mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) is an indolent B-cell lymphoma characterised by a fascinating interplay between chronic antigenic stimulation, an immune response insufficient for elimination of the antigen and a mucosal ‘battleground’. The archetype of this association is infection of the gastric mucosa with Helicobacter pylori (HP): a single course of antibiotic HP-eradication treatment may result in long-term remission in up to 80% of patients and is the gold standard for first-line therapy of HP-associated gastric MALT lymphoma. In extragastric or disseminated disease, treatment options range from wait and see in asymptomatic individuals to radiotherapy in localised stages, anti-CD20-antibodies in patients with low symptomatic burden and chemotherapy-based treatment or radio-immunotherapy in symptomatic disease. In addition, more refined immunomodulatory strategies beyond simple eradication of bacteria such as long-term use of the macrolide clarithromycin or the immunomodulatory drug lenalidomide are active. In view of the indolent clinical course, the least toxic individual treatment should be chosen in a disease usually not influencing overall survival in affected patients.

Epidemiology of Non-Hodgkin's Lymphoma

Non-Hodgins’s lymphoma (NHL) is the most common hematological malignancy worldwide, accounting for nearly 3% of cancer diagnoses and deaths. NHL is the seventh most prevalent cancer and has the sixth highest mortality among cancers in the US. NHL accounts for 4% of US cancer diagnoses, and incidence has increased 168% since 1975 (while survival has improved 158%). NHL is more common among men, those >65 years old, and those with autoimmune disease or a family history of hematological malignancies. NHL is a heterogenous disease, with each subtype associated with different risk factors. Marginal zone lymphoma (MZL) is strongly associated with Sjogren’s syndrome (SS) and Hashimoto’s thyroiditis, while peripheral T-cell lymphoma (PTCL) is most associated with celiac disease. Occupational exposures among farm workers or painters increases the risk of most of the common subtypes. Prior radiation treatment, obesity, and smoking are most highly associated with diffuse large B-cell lymphoma (DLBCL), while breast implants have been rarely associated with anaplastic large cell lymphoma (ALCL). Infection with Epstein–Barr Virus (EBV) is strongly associated with endemic Burkitts lymphoma. HIV and human herpes virus 8 (HHV-8), is predisposed to several subtypes of DLBCL, and human T-cell lymphoma virus (HTLV-1) is a causative agent of T-cell lymphomas. Obesity and vitamin D deficiency worsen NHL survival. Atopic diseases and alcohol consumption seem to be protective against NHL.

[Clinicopathological features and possible prognostic factors in parotid lymphomas]

OBJECTIVE

To investigate the clinicopathological features and prognostic factors in lymphoma of parotid origin.

METHODS

Clinicopathological data of the patients with parotid lymphoma who were initially diagnosed in Peking University Hospital of Stomatology from 2006 to 2016 were collected and analyzed retrospectively. The patients were followed-up for 5 to 149 months with a median period of 45 months, and the factors influencing the prognosis were evaluated.

RESULTS

A total of 41 patients with primary parotid lymphoma were included in this retrospective study. The rate of male to female was 1:2.15. The median age was 57 years (ranging from 8 months to 91 years). According to WHO classification, 40 cases (97.1%) were diagnosed as non-Hodgkin lymphoma (NHL), including 15 cases of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT), 14 cases of diffuse large B cell lymphoma (DLBCL) as well as 4 cases of follicular lymphoma, while other subtypes of NHL were rare. Only one case was diagnosed as Hodgkin lymphoma. Regarding the clinical staging at the initial diagnosis, 37 patients (90.2%) were diagnosed as stage IE or IIE of the disease, while 4 patients (9.8%) as stage IIIE or stage IVE. Seven patients (17.1%) had a history of Sjögren syndrome (SS), all of whom were MALT lymphoma. The mean ill duration of the 41 patients were 20.7 months. Thirty-two patients (78%) presented a slowly growing painless mass in the parotid gland. Treatment options included localized therapy and systemic therapy, all of whom had good curative effect. Nine patients (21.9%) died during the follow-up period. The overall survival rates of 2-year and 5-year were 84.5% and 81.3% respectively. The univariate analysis demonstrated statistically significant differences for accelerated growth of tumor (P=0.005), and presence of tumor capsule (P=0.011). The multi-univariate analysis demonstrated statistically significant differences for presence of tumor capsule (P=0.041).

CONCLUSION

A large majority of primary parotid lymphoma were NHL, among which MALT lymphoma and DLBCL were common subtypes. Most patients presented an indolent mass in parotid gland, which should be distinguished from the parotid benign tumors. SS is closely related to the pathogenesis of MALT lymphoma. The prognosis is better than that of other malignant parotid tumors. Absence of tumor capsule may predict a poor prognosis in patients with parotid lymphoma.

[Clinical features of malignant orbital lymphoma]

INTRODUCTION

The occurrence of malignant lymphoma (ML) among patients with malignant orbital tumors ranges between 10 and 37.3% making early diagnosis clarification crucial for timely treatment.

PURPOSE

To study clinical features of ML with consideration of its morphological type and localization in the orbit.

MATERIAL AND METHODS

Clinical picture of primary malignant orbital lymphoma of 34 patients (36 orbits) was examined retrospectively with consideration of the tumor's morphotype. Median observation time was 6 years. Patients aged between 34 and 84 years, female to male ratio was 1.27:1.

RESULTS

The final diagnoses were: small cell MALT-type ML (23 patients), large cell B-lymphoma (5 patients), diffuse malignant lymphoma (5 patients), T-cell lymphoma (1 female patient). Systemic changes developed in 29.41% of cases after 6.7 years on average. 23.53% of patients has died. Clinical signs of MALT-type ML were described with consideration of tumor's localization in the orbit, and clinical features of B-cell, large cell, diffuse and T-cell lymphoma were shown. Signs helping differentiate ML from false tumor, composite tear gland tumor and malignant orbital tumor were established.

CONCLUSION

Despite the higher prevalence of malignant MALT-type lymphoma, primary malignant orbital lymphoma is characterized by unfavorable vital prognosis: in a third of all cases, signs of systemic lesion develop in 6.7 years on average. Clinical picture of MALT-type ML is defined by tumor's localization in the orbit. Recurrence of MALT-type ML after combined treatment (surgical, radiotherapy, polychemotherapy) happens in every fourth case among patients with tumor primarily localized in the orbital cellular tissues or in the tear gland. Describing clinical features of primary malignant orbital lymphoma allows faster diagnosis clarification reducing the number of orbital diseases that require differential diagnositcs.

[Treatment of primary gastric lymphoma]

Stomach is the most common location of lymphoma in digestive tract, accounting for 50%-60% of gastrointestinal lymphomas. The most common histological types are low malignant mucosa-associated lymphoid tissue (MALT) lymphoma from non-Hodgkin lymphoma (NHL) and diffuse large B-cell and marginal zone B-cell lymphoma (DLBCL) from NHL. Chronic gastritis secondary to Helicobacter pylori(HP) infection has been considered a major predisposing factor for MALT lymphoma. At present, the most widely accepted initial therapy for localized disease is aimed at the eradication of HP using regimens combining antibiotics and proton-pump inhibitors. The irradiation has become the therapy of choice for patients with early stage MALT lymphoma without HP infection or with persistent lymphoma following antibiotic therapy. In all the patients with advanced disease, treatment options include chemotherapy and the use of monoclonal antibodies. Treatment of DLBCL in stomach is based on aggressive poly-chemotherapy that is usually combined with rituximab. The same guidelines followed for nodal aggressive lymphoma can also be applied to gastric lymphoma with aggressive histology as DLBCL. For localized stages (stages I( and II(), these guidelines suggest front-line therapy with 3 to 4 cycles of standard R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) followed by radiotherapy. Advanced stage patients (stage IIII() usually undergo only 6 to 8 cycles of R-CHOP in order to obtain a complete remission rate. Nowadays surgery is limited to rare cases and radiotherapy combined or not with chemotherapy represents an effective therapeutic option ensuring long-term, organ-salvage benefits mainly in aggressive histological types.

[Clinicopathological features and prognostic analysis of 151 patients with primary extra-nodal non-Hodgkin's lymphoma]

OBJECTIVE

To evaluate the epidermiology, clinicopathological features and prognosis of primary extra-nodal non-Hodgkin's lymphoma (PE-NHL).

METHODS

The clinicopathological data of 151 patients diagnosed as PE-NHL in the First Affiliated Hospital of Jilin University between January 2007 and December 2011 were reviewed and analyzed.

RESULTS

The proportion of PE-NHL patients was 58.8% among all the non-Hodgkin's lymphoma cases, with the average age of 52 years, and the male/female ratio was 1.16:1. The most frequently involved site was the stomach (30.5%) followed by nose and sinuses (19.9%) and Waldeyer's ring (17.2%). The most common subtype was diffuse large B-cell lymphoma (DLBCL) (55.0%), followed by NK/T (18.5%) and extra-nodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) ( 13.2%). The distribution of clinical stages was as follows: stage I 20.5%, II 29.8%, III 29.1%, and IV 20.5%. Most nasal PE-NHL is in early stages, with a proportion of 76.7% in stages I & II. The 3-year overall survival rate was 73.2% and 3-year progression free survival rate was 46.6% in the PE-DLBCL patients. The International Prognosis Index (IPI) could be used to estimate the prognosis of PE-DLBCL well. Multivariate analysis showed that ESR and curative effect of the first treatment were independent prognostic factors for PE-DLBCL patients.

CONCLUSIONS

The incidence of PE-NHL is quite high, and the most common primary extra-nodal site is the gastro-intestinal tract and the most common subtype is diffuse large B-cell lymphoma. Risk groups based on IPI can indicate the prognosis of PE-DLBCL to some extent, but only the ESR and curative effect of the first treatment are confirmed to be independent risk factors.

[A case report of isolated marginal zone B cell lymphoma originating from the parapharyngeal space]

This is a case report of isolated marginal zone B cell lymphoma originating from the parapharyngeal space and reaching up to the side of skull base. There are no obvious clinical symptoms of the marginal zone B cell lymphoma originating in the parapharyngeal space, the imaging examination of which showed slightly blurred edge mass shadow with heterogeneous textures and no specificity. The pathological examination revealed a large number of lymphocyte proliferation, which was not specific yet. Immunohistochemistry may show the tumor was monoclonal and positive to CD20 and CD79a positive. Marginal zone B cell lymphoma originating in the parapharyngeal space is a rare tumor with no specific clinical symptoms or early signs, and is easily misdiagnosed. The diagnosis should be confirmed based on pathological and immunohistochemical examination, and the tumor can be treated by surgery combined with chemotherapy.

MALT lymphomas -Treated with chemotherapy or radiotherapy: Clinical Features, Prognostic factors and Survival

OBJECTIVE

MALT lymphomas are a group of extranodal indolent lymphomas that usually present as stage IE. To clarify clinical features, treatment alternatives and outcomes, we evaluated 38 patients treated with chemotherapy or radiotherapy between 2000 and 2011.

PATIENTS AND METHODS

MALT lymphoma patients identified according to WHO classification and treated at KCCC between 2000 and 2011 were included in this study. Demographic and clinical data are presented as means or medians. Overall survival was estimated using the Kaplan-Meier method. Survival rates were compared using the log-rank test. A p value < 0.05 was considered significant.

RESULTS

The median age of the patients was 49 years and the male to female ratio was 2:1. Gastric MALT accounted for 63% of all patients and the most common presenting symptom was abdomen pain and dyspepsia. The common extra gastric sites were salivary glands, lung and orbit. 90% of the patients presented with early stage disease. Two patients had history of pre-existing autoimmune disease. Even among patients who had failed prior antibiotic therapy for Helicobacter pylori, treatment with chemotherapy achieved good results with 5 year survival of 80%.

CONCLUSION

MALT lymphomas are indolent neoplasm's with excellent long term outcome. There is no significant difference in survival between gastric and extra-gastric MALT lymphoma.

KEYWORDS

MALT lymphoma, Gastric Neoplasm, H. pylori.

Diagnosis and treatment of Helicobacter pylori infection

National Danish guidelines for the diagnosis and treatment of Helicobacter pylori (Hp) infection have been approved by the Danish Society for Gastroenterology. All patients with peptic ulcer disease, gastric cancer, and MALT lymphoma should be tested for Hp. We also recommend testing in first degree relatives to patients with gastric cancer, in NSAID-naive patients, who need long-term NSAID therapy, and in patients presenting with dyspepsia and no alarm symptoms. Non-endoscoped patients can be tested with a urea-breath test or a faecal antigen test. Endoscoped patients can be tested with a rapid urease test. Proton pump inhibitor therapy should be stopped at least 1 week prior to Hp testing. All infected patients should be offered Hp eradication therapy. First-line treatment is 7-day triple therapy with a proton pump inhibitor and clarithromycine in combination with metronidazole or amoxicilline. Quadruple therapy for 2 weeks with bismuthsubsalicylate, tetracycline, metronidazole and a proton pump inhibitor is recommended in case of treatment failure. Hp testing should be offered to all patients after eradication therapy but is mandatory in patients with ulcer disease, noninvasive gastric cancer or MALT lymphoma. Testing after eradication should not be done before 4 weeks after treatment has ended.

A unique case of IgD-only splenic marginal-zone lymphoma with mutated immunoglobulin genes: ontogenetic implications

Splenic marginal zone lymphoma (SMZL) is a rare indolent lymphoma subtype which accounts for less than 1% of all non-Hodgkin's lymphomas. We here report a unique case of IgD-only SMZL with mutated immunoglobulin variable region genes and discuss possible ontogenetic derivation.

[A case of H. pylori and API2-MALT1 gene-negative gastric mucosa-associated lymphoid tissue lymphoma with a carcinoma-like signet-ring cell lymphoepithelial lesion]

A 60-year-old woman presented in February 2003 with an ulcer on the lesser curvature of the anglus. The endoscopic biopsy specimens showed epithelial signet-ring cell associated with lymphoid infiltration, suggesting a diagnosis of gastric cancer. Histopathological examination confirmed the diagnosis of low-grade B-cell lymphoma of MALT with epithelial signet-ring cell lymphoepithelial lesion, which was negative for H. pylori and t (11;18) (q21;q21) translocation (API2-MALT1 gene). This case was treated with H. pylori eradication and additional radiation therapy, and the tumor was disappeared.

Remission of primary low-grade gastric lymphomas of the mucosa-associated lymphoid tissue type in immunocompromised pediatric patients

We report the remission of primary gastric lymphoma of the mucosa-associated lymphoid tissue (MALT) type in two immunocompromised pediatric patients. Patient 1, a 14-year-old boy in an immunocompromised state of unknown cause, complained of repeated abdominal pain. Examinations revealed gastric MALT with local invasion and lymph node involvement. Serum anti-Helicobacter pylori (H pylori) antibody was positive. H pylori eradication was abandoned due to its adverse effects. The MALT lesion spontaneously regressed over the next 24 months without any treatment for lymphoma. Patient 2, a 6-year-old boy, underwent cord blood transplantation for the treatment of adrenoleukodystrophy. He was administered immunosuppressants for graft-versus-host disease after transplantation. Nausea and hematochezia appeared and further examinations revealed gastric MALT with H pylori gastritis. Treatment consisting of medication for the H pylori infection alone eradicated the H pylori and completely resolved the patient’s MALT lesion, as well. Patients 1 and 2 were followed up over periods of 10 years and 3 years, respectively, without any signs of relapse. In conclusion, gastric lymphoma of the MALT type can be cured by conservative treatment even in immunocompromised pediatric patients.

Marginal zone lymphoma

Marginal zone lymphomas (MZLs) comprise 3 distinct entities: extranodal MZL of mucosa-associated lymphoid tissue (MALT), splenic MZL, and nodal MZL. Gastric MALT lymphoma is the most common extranodal MZL and often develops as a result of chronic Helicobacter pylori gastritis. Such cases frequently respond to antibiotics directed against H. pylori. Antigen-driven lymphomatous disease can also be seen in the association of Borrelia burgdorferi with MALT lymphoma of the skin, Chlamydia psittaci with MALT lymphoma of the ocular adnexa, Campylobacter jejuni with immunoproliferative disease of the small intestine, and hepatitis C with splenic MZL. This article discusses the pathogenesis and clinical features of MZL and the treatment options available to patients.

Molecular Cytogenetic Analysis of Chromosomal Breakpoints in the IGH, MYC, BCL6, and MALT1 Gene Loci in Primary Cutaneous B-cell Lymphomas

Chromosomal translocations affecting the IGH locus and various oncogene loci are recurrent in many types of systemic B-cell lymphomas. Hardly any data exist, however, on such translocations in primary cutaneous B-cell lymphomas (PCBCL). Here, a series of 29 PCBCL was investigated by interphase fluorescence in situ hybridization with probes for the IGH, MYC, BCL6, and MLT1 loci. None of the six follicle center cell lymphomas and nine marginal zone lymphomas showed evidence for any translocation affecting these loci. In contrast, 11 of 14 large B-cell lymphomas of the leg harbored breakpoints in at least one of the loci. Translocations involving the MYC locus were detected in six cases, five of them derived from a MYC/IGH juxtaposition and one from a translocation involving a non-IG gene partner. Rearrangements of the BCL6 locus were detected in five B-cell lymphomas of the leg, and involved IGH (two cases), IGL (one case), and non-IG genes (two cases). This study shows that large B-cell lymphomas of the leg display a pattern of chromosomal translocations similar to their systemic counterparts whereas primary cutaneous follicle center cell lymphomas and marginal zone lymphomas lack these typical chromosomal translocations.

The TRAF6 ubiquitin ligase and TAK1 kinase mediate IKK activation by BCL10 and MALT1 in T lymphocytes

The CARD domain protein BCL10 and paracaspase MALT1 are essential for the activation of IkappaB kinase (IKK) and NF-kappaB in response to T cell receptor (TCR) stimulation. Here we present evidence that TRAF6 ubiquitin ligase and TAK1 protein kinase mediate IKK activation by BCL10 and MALT1. RNAi-mediated silencing of MALT1, TAK1, TRAF6, and TRAF2 suppressed TCR-dependent IKK activation and interleukin-2 production in T cells. Furthermore, we have reconstituted the pathway from BCL10 to IKK activation in vitro with purified proteins of MALT1, TRAF6, TAK1, and ubiquitination enzymes including Ubc13/Uev1A. We find that a small fraction of BCL10 and MALT1 proteins form high molecular weight oligomers. Strikingly, only these oligomeric forms of BCL10 and MALT1 can activate IKK in vitro. The MALT1 oligomers bind to TRAF6, induce TRAF6 oligomerization, and activate the ligase activity of TRAF6 to polyubiquitinate NEMO. These results reveal an oligomerization --> ubiquitination --> phosphorylation cascade that culminates in NF-kappaB activation in T lymphocytes.

MALT1/paracaspase is a signaling component downstream of CARMA1 and mediates T cell receptor-induced NF-kappaB activation

T cell receptor (TCR) induces a series of signaling cascades and leads to activation of multiple transcription factors, including NF-kappaB. Although the mechanism of TCR-induced NF-kappaB activation is not fully understood, recent studies indicate that Bcl10 and CARMA1, two adaptor/scaffold proteins, play essential roles in mediating TCR-induced NF-kappaB activation. MALT1/paracaspase is a caspase-like protein that contains an N-terminal death domain, two Ig-like domains, and a C-terminal caspase-like domain. It binds to Bcl10 through its Ig-like domains and cooperates with Bcl10 to activate NF-kappaB. Recently, it has been shown that MALT1 is involved in mediating TCR signal transduction, leading to activation of NF-kappaB. In this study, we show that MALT1 is recruited into the lipid rafts of the immunological synapse following activation of the TCR and the CD28 coreceptor (CD3/CD28 costimulation). This recruitment of MALT1 is dependent on CARMA1 because CD3/CD28 costimulation failed to recruit MALT1 into lipid rafts in CARMA1-deficient T cells. In addition, we also found that MALT1 not only binds to Bcl10 directly, but also associates with CARMA1 in a Bcl10-independent manner. Therefore, MALT1, Bcl10, and CARMA1 form a trimolecular complex. Expression of a MALT1 deletion mutant containing only the N-terminal death domain and the two Ig-like domains completely blocked CD3/CD28 costimulation-induced, but not tumor necrosis factor-alpha-induced, NF-kappaB activation. Together, these results indicate that MALT1 is a crucial signaling component in the TCR signaling pathway.

Improved technique for fluorescence in situ hybridisation analysis of isolated nuclei from archival, B5 or formalin fixed, paraffin wax embedded tissue

Fluorescence in situ hybridisation (FISH) is an effective method to detect chromosomal alterations in a variety of tissue types, including archived paraffin wax embedded specimens fixed in B5 or formalin. However, precipitating fixatives such as B5 have been known to produce unsatisfactory results in comparison with formalin when used for FISH. This study describes an effective nuclear isolation and FISH procedure for B5 and formalin fixed tissue, optimising the nuclear isolation step and nuclei pretreatments using tonsil and mantle cell lymphoma specimens. The protocol presented can be used to isolate nuclei and perform FISH on B5 or formalin fixed, paraffin wax embedded samples from a variety of tissue types.

Bimp1, a MAGUK family member linking protein kinase C activation to Bcl10-mediated NF-kappaB induction

Bcl10 and MALT1, products of distinct chromosomal translocations in mucosa-associated lymphoid tissue lymphoma, cooperate in activating NF-kappaB. Mice lacking Bcl10 demonstrate severe immunodeficiency associated with failure of lymphocytes to activate nuclear factor kappaB (NF-kappaB) in response to antigen receptor stimulation and protein kinase C activation. We characterize Bimp1, a new signaling protein that binds Bcl10 and activates NF-kappaB. Bimp1-mediated NF-kappaB activation requires Bcl10 and IkappaB kinases, indicating that Bimp1 acts upstream of these mediators. Bimp1, Bcl10, and MALT1 form a ternary complex, with Bcl10 bridging the Bimp1/MALT1 interaction. A dominant negative Bimp1 mutant inhibits NF-kappaB activation by anti-CD3 ligation, phorbol ester, and protein kinase C expression. These results suggest that Bimp1 links surface receptor stimulation and protein kinase C activation to Bcl10/MALT1, thus leading to NF-kappaB induction.

Inflammatory pseudotumor of the submandibular gland: report of a case presenting with autoimmune disease-like clinical manifestations

We report a rare case of inflammatory pseudotumor arising in the submandibular gland, which presented with autoimmune disease-like clinical manifestations. A 70-year-old Japanese man developed masses in both submandibular regions. Laboratory tests revealed polyclonal hypergammaglobulinemia, high titers of antinuclear antibody, and a positive thyroid test. Histologically, the lesion was composed of multiple nodules separated by thick fibrous bands and contained a few atrophic lymphoid follicles and residual ductal structures. At higher magnification, the nodules contained numerous mature plasma cells mixed with myofibroblasts, lymphocytes, and histiocytes. Occasionally, the myofibroblasts were arranged in poorly formed fascicles and in a storiform pattern. Polymerase chain reaction analysis failed to demonstrated the rearrangement of the immunoglobulin heavy-chain gene. The patient was free of disease after 72 months follow-up. Marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type arising from salivary glands occasionally showed prominent plasma cell differentiation. The present case indicates that inflammatory pseudotumor should be added to the list of different diagnoses for mucosa-associated lymphoid tissue-type lymphoma of the salivary glands.

Complete remission of generalized relapsed extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type of the gastrointestinal tract after high-dose chemotherapy and autologous peripheral stem cell transplantation

Due to their homing properties, extranodal marginal zone B-cell lymphoma (MZBL) of mucosa-associated lymphoid tissue (MALT) type remain localized for long periods of time, and therefore have an excellent prognosis. However, if generalization and/or transformation into a diffuse large-cell lymphoma occurs, the prognosis deteriorates and no established treatment concepts are yet available. We report about a 57-year-old female patient with relapsed transformed stage-IV extranodal MZBL of MALT type of the entire gastrointestinal tract who was successfully treated using salvage chemotherapy followed by BEAM conditioning [BCNU 1,3-bis-2-(chloroethyl-1-nitrosourea), etoposide, cytosine arabinoside, and melphalan] and autologous peripheral stem cell transplantation. Follow-up revealed a sustained complete remission for 22 months.

Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas

The t(11;18)(q21;q21) is thought to represent an important primary event in the development of marginal zone lymphomas, although an accurate estimation of the frequency and distribution of this genetic alteration among nodal, splenic, and extranodal marginal zone lymphoma types has yet to be determined. Recently, molecular genetic studies have shown that this translocation results in the fusion of the API2 gene on chromosome 11 and a novel gene termed MALT1 on chromosome 18. To investigate the incidence of API2-MALT1 fusion transcripts among marginal zone lymphomas and to determine possible marginal zone lymphoma subtype associations, we used reverse transcriptase-polymerase chain reaction to analyze RNAs extracted from frozen tissue samples of 99 marginal zone lymphomas. Fifty-seven involved diverse extranodal sites including 14 stomach, 11 lung, 7 orbit, 7 parotid, 5 thyroid, 5 lacrimal gland, 3 small intestine, 2 large intestine, 1 kidney, 1 paraspinal region and 1 skin. Twenty-one primary splenic and twenty-one primary nodal marginal zone lymphomas were also studied. API2-MALT1 fusion transcripts were detected in 12 of 57 extranodal marginal zone lymphomas (21%), but in none of the nodal or splenic cases. The cDNA sequences of the fusion transcripts were determined, revealing variation in the coding sequence fusion point for both API2 and MALT1. The findings suggest that t(11;18)(q21;q21) is restricted to extranodal marginal zone lymphomas and that these tumors have distinct genetic etiologies in comparison with their splenic and nodal counterparts.

Gastric mucosa-associated lymphoid tissue in autoimmune thyroid diseases

BACKGROUND

There is increasing evidence for a link between Helicobacter pylori infection and the development of lymphoid follicles in the gastric mucosa. It is not known whether other factors may also play a role. The aim of this study was to investigate the role played by the host with peculiar immunogenic disorders, in the presence or absence of a known antigenic stimulus such as H. pylori. For this, we studied patients with autoimmune thyroid diseases.

METHODS

Thirty patients with autoimmune thyroid diseases and 30 dyspeptic patients without a history of thyroid disorders (as control group) underwent upper endoscopy. Lymphoid follicles and H. pylori status were assessed by histopathologic and enzymatic analysis.

RESULTS

Organized mucosa-associated lymphoid tissue was found in 73.3% of the patients and in 33.3% of control group. Lymphoid follicles were found in 87.5% of the H. pylori-positive patients and in 57.1% of the H. pylori-negative patients (P = NS). In the control group these follicles were present in 50% of H. pylori-positive subjects and in 14.3% of those who were H. pylori-negative.

CONCLUSIONS

lYMPHOID follicles in the gastric mucosa are common in autoimmune thyroid diseases. Besides H. pylori infection, other factors (environmental, unknown infectious agents) or mechanisms related to the underlying disease may play a causal role.