Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the dura mimicking meningioma: a case report and literature review.

MALT lymphoma of the dura is a very rare type of low-grade B-cell lymphoma. Little more than 100 cases have been reported in the literature to date. We report a 43-year-old woman who was referred to hospital because of a series of three tonic-clonic seizures on the day of admission. Neurological examination revealed confusion and aphasia. Magnetic resonance imaging (MRI) showed a contrast-enhanced, broad-based lesion along the dura in the left parieto-occipital area. The suspicion of an en plaque meningioma was raised. The tumour invaded the brain parenchyma with visible extension into the brain sulci. There was a marked brain oedema surrounding the lesion and causing the midline shift 8 mm to the right. After stabilization of neurological condition (intravenous diuretics and steroids), the operation was performed. The diagnosis of dural MALT lymphoma was established. During the pathological examination, it was especially problematic to distinguish MALT lymphoma from follicular lymphoma, but the final diagnosis was MALT lymphoma. Surgical partial removal with additional R-CVP immunochemotherapy (rituximab, cyclophosphamide, vincristine and prednisone) resulted in complete remission. The follow-up period is 1 year. Our presented case of a MALT lymphoma highlights the fact that surgical partial removal with additional immunochemotherapy is an available option in these rare intracranial tumours.

Observation of lymphadenopathy, systemic symptoms, and treatment in suspected indolent cutaneous B-cell lymphomas.

BACKGROUND: Following the initial diagnosis of a marginal zone or follicle center lymphoma on skin biopsy, patients undergo staging to determine the extent of disease. OBJECTIVE: We sought to characterize the frequency that these patients were found to have a systemic nodal disease upon work-up as well as the impact of imaging on disease management. METHODS: We conducted a retrospective chart review of patients presenting with a working diagnosis of PCMZL or PCFCL treated at The Ohio State University from 1990 to 2022. Data collected included: patient history, progress notes, virtual encounters, laboratory results, presentation features, imaging, and pathology. Biomarkers included ANA, SSA/SSB, BCL6 and H. Pylori labs, bone marrow biopsies, positive imaging, and need of systemic medication and mortality. RESULTS: 71 patients with suspected PCMZL and PCFCL were identified. 66 of 71 patients underwent imaging. Of this group, 12 patients (9 with suspected PCFCL and 3 with suspected PCMZL) demonstrated lymphadenopathy on imaging. Of these 12 patients, 5 underwent biopsy of suspected lymph nodes, and 3 had biopsy-proven nodal involvement and received systemic therapy. Of the remaining 7 patients with evidence of lymphadenopathy on imaging, 4 were thought to have reactive lymph nodes, and 3 were treated empirically with systemic chemotherapy due to the extent or progression of their disease. Of patients with imaging negative for lymphadenopathy, 3 of 52 (5.8%) patients with received systemic treatment, while 49 of 52 patients (94.2%) received localized treatment. LIMITATIONS: Most of the relationships between this data were correlational and patients selected for this study were limited to a single institution. CONCLUSION: Prospective study of the role of imaging without subsequent lymph biopsy to direct treatment decisions is warranted.

A Case of Esophageal MALT Lymphoma Mimicking a Subepithelial Tumor.

Mucosa-associated lymphoid tissue (MALT) lymphoma, also known as extranodal marginal zone lymphoma, is a low-grade B-cell lymphoma that can develop in the mucosal layer of various organs, including the gastrointestinal tract, salivary glands, lungs, and skin. The most common site is the gastrointestinal tract, particularly the stomach. On the other hand, primary esophageal lymphomas are extremely rare. MALT lymphomas can undergo histological transformation into more aggressive B-cell lymphomas, such as diffuse large B-cell lymphoma, resulting in a poor prognosis. This paper reports a rare case of primary esophageal MALT lymphoma mimicking a subepithelial tumor located in the lower esophagus that was treated successfully with radiotherapy. MALT lymphoma should be included in a differential diagnosis when subepithelial tumors are found in the esophagus, particularly if endoscopic ultrasonography reveals the tumor to be located in the deep mucosal and submucosal layers. Following the precise diagnosis, accurate staging and appropriate treatment are crucial. Regular follow-up is necessary to assess the possibility of recurrence or transformation to high-grade lymphoma.

Histopathological staging and differential diagnosis of marginal zone lymphoma of gastric mucosa-associated lymphoid tissue.

The purpose of this study was to explore the histopathological staging and differential diagnosis of marginal zone lymphoma in gastric mucosa-associated lymphoid tissue (MALT lymphoma). We performed detailed histomorphology and immunohistochemistry investigations as well as genetic testing on endoscopic biopsy and endoscopic mucosal resection specimens from 18 patients with gastric MALT lymphoma. We found that gastric MALT lymphoma typically begins as a small, isolated area outside the lymphoid follicular mantle zone or proliferates in a multifocal, patchy manner, gradually spreads to the interfollicular zone, forming diffuse proliferation, invades the gastric mucosal glands, and infiltrates or proliferates into the center of peripheral reactive lymphoid follicles. Abnormally proliferating lymphocytes invade the surrounding lymphoid follicles, resulting in damage, atrophy, and disappearance of their normal follicles as well as of the gastric mucosa glands, forming diffuse proliferation. Redifferentiation and proliferation lead to the transformation of lymphocytes; that is, MALT transitions into highly invasive lymphoma. Based on our findings in this study, we propose the following five stages in the process of development and progression of gastric MALT lymphoma: the stage of cell proliferation outside the lymphoid follicular mantle zone; the stage of heterogeneous proliferative lymphoepithelial lesion; the stage of reactive lymphoid follicular implantation; the stage of lymphoid follicular clonal proliferation; and the stage of MALT transforming into highly invasive lymphoma. We examined the differential diagnosis of histopathological features at each stage. The clinicopathological staging of gastric MALT lymphoma can help clinicians provide accurate treatment and track malignant cell transformation, thus playing a significant role in controlling its development and progression.

Recurrent Marginal Zone Lymphoma with Bone Marrow Involvement Detected by ¹8F-FDG PET/CT and Biopsy: A Diagnostic Challenge.

BACKGROUND Marginal zone lymphoma is a low-grade, B-cell, non-Hodgkin lymphoma. Bone marrow involvement (BMI) of leukemia or lymphoma can usually be displayed in fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹8F-FDG PET/CT) with high standardized uptake values (SUV), while diffuse homogeneous ¹8F-FDG bone marrow uptake (BMU) in PET/CT primarily reflects hyperplastic bone marrow status. This report is of a 74-year-old man presenting with anemia and a diagnosis of recurrent marginal zone lymphoma with bone marrow involvement identified with 18F-FDG PET/CT imaging and biopsy. CASE REPORT A 64-year-old man with severe anemia and body weight loss of 7 kg in 1 month was diagnosed with marginal zone lymphoma, stage III, in July 2011. He went into complete remission in April 2012 after 6 cycles of chemotherapy, with Hb restored. Anemia and diffuse homogeneous ¹8F-FDG BMU in PET/CT were then noted during a routine check-up in October 2021, and recurrent disease was established through positive biopsy of subcutaneous nodules and bone marrow. Subsequent complete remission after 6 cycles of combination therapy was validated with pathologically negative BMI, the resolution of the slightly enhanced ¹8F-FDG BMU in PET/CT, and restored hemoglobin. CONCLUSIONS This report has highlighted the importance of follow-up for patients with lymphoma and supports the diagnostic role of ¹8F-FDG PET/CT imaging and the pathological verification in identifying malignant involvement in bone marrow.

Declining incidence and improving survival of ocular and orbital lymphomas in the US between 1995 and 2018.

This epidemiological study examined ocular and orbital lymphomas in the United States from 1995 to 2018, using data from the North American Association of Central Cancer Registries database of 87,543 patients with ocular and adnexal malignancies. We identified 17,878 patients (20.4%) with ocular and orbital lymphomas, with an age-standardized incidence rate (ASIR) of 2.6 persons per million (ppm). The incidence was the highest in the orbit (ASIR = 1.24), followed by the conjunctiva (ASIR = 0.57). Non-Hodgkin B-cell lymphoma was the most prevalent subtype (85.4%), particularly marginal-zone lymphoma (45.7%). Racial disparities were noted, with Asia-Pacific Islanders showing the highest incidence (orbit, 1.3 ppm). The incidence increased significantly from 1995 to 2003 (Average Percent Change, APC = 2.1%) but declined thereafter until 2018 (APC = - 0.7%). 5-year relative survival (RS) rates varied, with the highest rate for conjunctival lymphoma (100%) and the lowest for intraocular lymphoma (70.6%). Survival rates have generally improved, with an annual increase in the 5-year RS of 0.45%. This study highlights the changing epidemiological landscape, pointing to initial increases and subsequent decreases in incidence until 2003, with survival improvements likely due to advancements in treatment. These findings underscore the need for further research to investigate the root causes of these shifts and the declining incidence of ocular lymphoma.

Low-grade malt lymphoma of the nasopharynx in young adults: Successful treatment of a rare diagnosis at a rare site by radiotherapy.

INTRODUCTION: Mucosa Associated Lymphoid Tissue (MALT) lymphoma is the third most common subgroup of Non-Hodgkin's lymphoma and is the most common type of primary extranodal lymphoma. They are rarely found in the nasopharyngeal region and their mean age at presentation is the sixth decade of life. MATERIALS AND METHODS: We present the clinical, pathological, treatment and 5-year follow-up data of 5 cases of nasopharyngeal MALT lymphoma treated with definitive radiotherapy at our hospital, between 2009 and 2011. RESULTS: The average age of diagnosis was 27 years which is more than a decade earlier than what has been reported previously. Clinical symptoms included nasal obstruction, tinnitus and hearing loss. All five patients had locoregional disease. They were treated by definitive radiotherapy to a dose between 30 to 40 Gy. At 5 years of follow-up, 4 patients were in complete remission while one had disease relapse. CONCLUSION: The younger age of presentation compared to older reports in this rare subsite was an interesting finding in our study. The authors speculate that rising levels of particulate air pollution may have played a part in the etiology in this younger population. Our series shows that despite the younger age, the disease displays an indolent course and responds well to radiotherapy alone as the primary treatment. Recurrence or disseminated disease is also highly treatable with systemic chemotherapy.

Primary MALT lymphoma of the breast: pathological and radiological characteristics.

PURPOSE: Primary Mucosa-associated lymphoid tissue (MALT) lymphoma is a rare diagnosis in the breast, and clinical diagnosis based on radiological features is often challenging. This study aimed to evaluate the clinicopathological, and radiological characteristics of the patients diagnosed with primary breast MALT lymphoma. METHODS: This study examined 18 cases of primary MALT lymphoma of the breast diagnosed at a single tertiary center between January 2002 to December 2020. Medical charts, radiological imaging and original pathology slides were reviewed for each case. RESULTS: All cases were female (gender assigned at birth) and presented with a palpable mass or an incidental imaging finding. Imaging presentation ranged from mammographic asymmetries, circumscribed masses, and ultrasound masses lacking suspicious features. Seventeen cases were biopsied under ultrasound; one received a diagnostic excision biopsy. Microscopic examination of the breast specimens demonstrated atypical small lymphocyte infiltration with plasmacytoid differentiation and rare lymphoepithelial lesions. Immunohistochemistry was performed in all cases and established the diagnosis. Most patients were treated with radiotherapy, and only three were treated with chemotherapy. The median follow-up period was 4 years and 7.5 months, and all patients were alive at the last follow-up. CONCLUSION: Primary MALT breast lymphomas are usually indolent and non-systemic, and local radiotherapy may effectively alleviate local symptoms. Radiological findings show overlap with benign morphological features, which can delay the diagnosis of this unusual etiology. Although further studies involving a larger cohort could help establish the clinical and radiological characteristics of primary breast MALT lymphomas, pathology remains the primary method of diagnosis. TRIAL REGISTRATION NUMBER: University Health Network Ethics Committee (CAPCR/UHN REB number 19-5844), retrospectively registered.

Histological criteria for selecting patients who need clonality test for non-gastric MALT lymphoma diagnosis.

The histological diagnosis of extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is difficult for pathologists. Recently, digital pathology systems have been widely used to provide tools that can objectively measure lesions on slides. In this study, we measured the extent of marginal zone expansion in suspected MALT lymphoma cases and compared the results with those of a molecular clonality test. In total, 115 patients who underwent an IGH gene rearrangement test for suspected MALT lymphoma were included in this study. All cases were histologically classified into three patterns; "small lymphoid aggregates with no germinal center (Pattern 1)," "lymphoid follicles with germinal center (Pattern 2)" and " fused marginal zone or diffuse small lymphocytic proliferation (Pattern 3)." The proportions of monoclonality in Pattern 1, 2, and 3 were 25.0%, 55.0%, and 97.9%, respectively. The ratios of marginal zone thickness to germinal center diameter and entire lymphoid follicle area to germinal center area were measured in Pattern 2 cases using a digital pathology system. Combining the width cutoff of 1.5 and the areal cutoff of 3.5, the sensitivity, specificity, positive predictive value, and negative predictive value for MALT lymphoma were 96.97%, 70.37%, 80.00%, and 95.00%, respectively. In conclusion, through objective measurement of the marginal zone, suspected cases of MALT lymphoma requiring a molecular clonality test can be effectively selected.

Two lymphoma histotypes and papillary thyroid carcinoma coexisting on Hashimoto ground: a case report and review of the literature.

BACKGROUND: Papillary carcinoma is the most frequent type of thyroid carcinoma, while primary thyroid lymphoma is uncommon disease. The coexistence of these entities has already been described, and the common risk factor is considered Hashimoto thyroiditis. The two most frequent histotypes of primary thyroid lymphoma are diffuse large B-cell and mucosa-associated lymphoid tissue lymphoma, but the coexistence of both with papillary carcinoma is rarely reported. METHODS: We present a case of a previously healthy 57-years old male with rapidly growing lump on the right side of the neck. Ultrasonography revealed nodules in both thyroid lobes. Fine needle aspiration cytology and pertechnetate scintigraphy were performed. Due to the Bethesda T-5 in the "cold" nodule of the right lobe, surgery with histopathological and immunohistochemistry analysis was indicated. RESULTS: Histopathological and immunohistochemistry methods confirmed concomitant malignancies in the thyroid gland: diffuse large B-cell lymphoma and papillary carcinoma in the right, and mucosa-associated lymphoid tissue lymphoma in the left lobe with Hashimoto thyroiditis in the remaining tissue. Patient underwent therapy procedures and was without signs of local recurrence or metastatic spread on subsequent follow-up. CONCLUSIONS: Sudden appearance of the neck mass in patients with Hashimoto thyroiditis should raise suspicion on primary thyroid lymphoma and be promptly taken in the diagnostic workup, including fine needle aspiration cytology. Pathology with immunohistochemistry is crucial for further clinical decision making. Since the standardized protocol in management of these complex patients is missing, personal approach and close collaboration between cytologist, pathologist, surgeon, haematologist and nuclear medicine specialist is essential.

The potential value of ultrasound in predicting local refractory/relapse events in primary thyroid lymphoma patients.

BACKGROUND: Primary thyroid lymphoma (PTL) is a rare malignant disorder, and ultrasound plays an important role in PTL diagnosis and follow-up surveillance. Prediction of refractory/relapse events in PTL patients is an essential issue, yet no ultrasonic PTL features have been discovered to be related to refractory/local relapse events. METHODS: From January 2008 to September 2022, newly diagnosed PTL patients in our center who underwent standard first-line treatment and received an ultrasound examination before treatment were enrolled. Data regarding patients' clinical and sonographic features, as well as their therapeutic responses were collected. Subjects with an ideal prognosis were compared to those with refractory/relapse events. RESULTS: In total, 37 PTL patients were analyzed, including 26 with diffuse large B-cell lymphoma, 2 with follicular lymphoma and 9 with mucosa-associated lymphoid tissue lymphoma. During the median follow-up of 25 months, 30 patients obtained a complete response, 4 were refractory patients, and 3 experienced local relapse. No significant difference was detected in the baseline clinical characteristics between patients with an ideal prognosis and those with refractory/local relapse events. In terms of sonographic features, however, an event-free survival (EFS) curve comparison revealed that patients with bilobar enlargement (defined as an anterior-posterior diameter > 2.5 cm on both sides of thyroid lobes) had a poorer EFS than those without (P < 0.0001), and patients with diffuse type had a poorer EFS than those with mixed/nodular types (P = 0.043). No significant difference was observed in EFS between patients with or without signs of suspicious cervical lymph node metastasis, rich blood signal distribution or symptoms of trachea compression. CONCLUSIONS: PTL patients with an anterior-posterior diameter > 2.5 cm for both thyroid lobes or PTL patients of the diffuse ultrasound type could be prone to refractory/local relapse events.

H pylori-Negative MALT-Associated Extranodal Marginal Zone Lymphoma: A Comprehensive Case Report and Literature Review.

Extranodal marginal zone B-cell lymphoma (ENMZL) of mucosa-associated lymphoid tissue (MALT), a rare subtype of B-cell lymphoma, is typically associated with Helicobacter pylori (H pylori) infection, especially in gastric cases. However, this article presents 2 unique cases of H pylori-negative colonic ENMZL, challenging the conventional understanding of the disease. The first case involves an 80-year-old male diagnosed with Stage 1E ENMZL in the descending colon, and the second describes a 74-year-old male with sigmoid colon ENMZL. Both cases lacked H pylori infection, adding complexity to their management. Accompanying these case studies is a comprehensive literature review, delving into the epidemiology, pathology, clinical features, diagnosis, and treatment of H pylori-negative ENMZL, with a focus on gastrointestinal involvement. This review highlights the importance of considering H pylori-negative cases in ENMZL diagnosis and management, illustrating the need for further research and individualized treatment approaches in this uncommon lymphoma subtype.

[Chinese expert consensus on the diagnosis and management of ocular adnexal extranodal marginal zone mucosa-associated lymphoid tissue lymphoma (2023 edition)].

Ocular adnexal extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (OAML) is a common malignant tumor that affects the ocular adnexal region. The incidence of OAML is increasing due to the aging population. The tumor invades the ocular adnexal region, which can result in abnormal ocular appearance and function, thereby reducing the quality of life. Currently, there is no standardized diagnosis and management guideline for OAML. To enhance the standardization of diagnosis and management in OAML, a collaborative effort was undertaken by esteemed organizations in China. The Cellular Immune Therapy Committee of China Association for Promotion of Health Science and Technology, the Ocular Tumor Committee of Chinese Medical Doctor Association for Ophthalmologist Branch, the Imaging Medicine Branch of Chinese International Exchange and Promotion Association for Medical and Healthcare, the Tumor and Microecology Professional Committee of China Anti-cancer Association, and the Lymphoma Immunotherapy Committee of Beijing Cancer Prevention Society jointly convened a panel of experts to develop the inaugural "Chinese Expert Consensus on the Diagnosis and Management of ocular adnexal extranodal marginal zone mucosa-associated lymphoid tissue lymphoma (2023 edition)"..

Multimodal and spatially resolved profiling identifies distinct patterns of T cell infiltration in nodal B cell lymphoma entities.

The redirection of T cells has emerged as an attractive therapeutic principle in B cell non-Hodgkin lymphoma (B-NHL). However, a detailed characterization of lymphoma-infiltrating T cells across B-NHL entities is missing. Here we present an in-depth T cell reference map of nodal B-NHL, based on cellular indexing of transcriptomes and epitopes, T cell receptor sequencing, flow cytometry and multiplexed immunofluorescence applied to 101 lymph nodes from patients with diffuse large B cell, mantle cell, follicular or marginal zone lymphoma, and from healthy controls. This multimodal resource revealed quantitative and spatial aberrations of the T cell microenvironment across and within B-NHL entities. Quantitative differences in PD1+ TCF7- cytotoxic T cells, T follicular helper cells or IKZF3+ regulatory T cells were linked to their clonal expansion. The abundance of PD1+ TCF7- cytotoxic T cells was associated with poor survival. Our study portrays lymphoma-infiltrating T cells with unprecedented comprehensiveness and provides a unique resource for the investigation of lymphoma biology and prognosis.

The prognosis of patients with primary pulmonary mucosa-associated lymphoid tissue lymphoma: Treated with surgery or chemotherapy?

OBJECTIVES: The goal of this project was to evaluate the effect of surgical treatment and the long-term survival of patients with staged IE/IIE pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma. METHODS: From January 2004 to December 2018, we retrospectively analysed 96 patients diagnosed with low-stage primary pulmonary MALT lymphoma according to the modified Ann Arbor staging system (IE/IIE). We compared the outcomes of different treatment modalities for staged IE/IIE MALT lymphoma. Progression-free survival (PFS) and overall survival were estimated using Kaplan-Meier curves, and the differences were compared using the log-rank test. The Cox proportional hazards model was used in this study. RESULTS: The median PFS time of low-staged MALT lymphomas was 118 months. The overall survival and PFS of the radical surgery group and the biopsy + chemotherapy group suggested no significant difference (P = 0.63, P = 0.65). Patients positive for Blc-2 and Ki-67 suffered from a compromised PFS (P = 0.023, P = 0.006). The Cox adjusted proportional hazards model analysis suggested that surgical procedures were not protective factors for patients with low-staged (IE/IIE) pulmonary MALT lymphoma, whereas being positive for Blc-2 and Ki-67 was a risk factor for patients with low-staged pulmonary MALT lymphoma (hazard ratio: 9.567; P = 0.044; hazard ratio: 6.042, P = 0.049). CONCLUSIONS: Our findings suggested that for staged IE/IIE pulmonary MALT lymphoma, radical surgical resection did not provide a survival benefit compared with chemotherapy after biopsy. Thus, radical surgery may be avoided unless biopsy is necessary for a diagnosis that requires sublobar resection. For those lesions that were Blc-2- or Ki-67-positive, compromised survival may be suggested.

Long-term monitoring of gastric mucosa-associated lymphoid tissue lymphoma in patients with extra copies of the MALT1 gene.

The objective of this study was to clarify the long-term prognosis of patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma with additional copies of MALT1. In this multicenter retrospective study, we enrolled 145 patients with gastric MALT lymphoma who underwent fluorescence in situ hybridization (FISH) analysis to detect t(11;18) translocation. The patient cohort was divided into three groups: Group A (n = 87), comprising individuals devoid of the t(11;18) translocation or extra MALT1 copies; Group B (n = 27), encompassing patients characterized by the presence of the t(11;18) translocation; and Group C (n = 31), including patients with extra MALT1 copies. The clinical outcomes in each cohort were collected. Over the course of a mean follow-up of 8.5 ± 4.2 years, one patient died of progressive MALT lymphoma, while 15 patients died due to etiologies unrelated to lymphoma. The progression or relapse of MALT lymphoma was observed in 11 patients: three in Group A, two in Group B, and six in Group C. In Groups A, B, and C, the 10-year overall survival rates were 82.5%, 93.8%, and 86.4%, respectively, and the 10-year event-free survival rates were 96.1%, 96.0%, and 82.9%, respectively. The event-free survival rate in Group C was significantly lower than that in Group A. However, no differences were observed in the 10-year event-free survival rates among individuals limited to stage I or II1 disease (equivalent to excluding patients with stage IV disease in this study, as there were no patients with stage II2), with rates of 98.6%, 95.8%, and 92.3% for Groups A, B, and C, respectively. In conclusion, the presence of extra copies of MALT1 was identified as an inferior prognostic determinant of event-free survival. Consequently, trisomy/tetrasomy 18 may serve as an indicator of progression and refractoriness to therapeutic intervention in patients with gastric MALT lymphoma, particularly stage IV gastric MALT lymphoma.

Aggressive Lymphoplasmacytic Neoplasm With an Unusual In-frame Deletion of MYD88 Associated With TRAF3 and TP53 Mutations and Complex Karyotype.

Lymphoplasmacytic lymphoma often needs to be differentiated from other B-cell lymphomas with plasmacytic differentiation, especially marginal zone cell lymphoma. Molecular detection of MYD88 p.L265P hotspot mutation supports the diagnosis of lymphoplasmacytic lymphoma since it is seen in about 90% of such lymphoma, which is much higher than other B-cell lymphomas. MYD88 p.L265P is a gain-of-function mutation that enhances the activity of the NF-κB signaling pathway and therefore drives lymphomagenesis. Other mutations in MYD88 are rarely reported. This study aims to report an unusual MYD88 in-frame deletion in an aggressive lymphoplasmacytic neoplasm. This is an IgM-positive, CD5- and CD10-negative mature B-cell lymphoma with prominent plasmacytic differentiation and aggressive features. The clinical and pathologic findings were most consistent with lymphoplasmacytic lymphoma. Next-generation sequencing identified an unusual MYD88 in-frame deletion in the absence of the hotpot p.L265P mutation. Other concurrent pathogenic mutations also include truncating mutations of TRAF3, which is a negative regulator of the NF-κB signaling pathway, and a missense mutation of TP53. Karyotype analysis showed complex karyotypes, including chromosome 6q deletion. By searching literature and online cancer databases, we identified only 8 other mature B-cell lymphomas with MYD88 in-frame deletions, but none of them was diagnosed with lymphoplasmacytic lymphoma. Recognizing such in-frame deletions is necessary to help understand the mutational spectrum of MYD88 in B-cell lymphomas. It remains to be further investigated whether such MYD88 in-frame deletions are also overrepresented in lymphoplasmacytic lymphoma among other B-cell lymphomas.

Novel identification of t(14;18)(q32;q21)/IGH::MALT1 in chronic lymphocytic leukaemia.

Chronic lymphocytic leukaemia (CLL) is a clonal B-cell malignancy and remains a chronic disease despite improvements in clinical outcomes since the use of targeted therapies. Both clinical and biological parameters are important for determining prognosis. Unlike other mature B-cell lymphomas, translocations involving the immunoglobulin heavy chain (IGH) locus are uncommon in CLL. There have been few case reports of CLL harbouring t(14;18)/IGH::BCL2 and t(14;19)/IGH::BCL3. Here we describe the first two cases of patients with CLL with documented t(14;18)(q32;q21)/IGH::MALT1. Both cases in this report were associated with lower-risk biological parameters. Thus, FISH testing for MALT1 in cases with unknown IGH translocation partners in the setting of CLL should be implemented in clinical practice to better define such cases.