Diagnosis and Treatment of Low-Grade Marginal Zone B-cell Lymphoma With Psychiatric Overlap.

This case report delineates the intricate interplay between psychiatric and oncological pathology in a 72-year-old male diagnosed with low-grade marginal zone B-cell lymphoma and severe psychiatric disturbances, including catatonia. The presentation of severe psychiatric symptoms initially obscured the underlying lymphoma, delaying diagnosis and complicating clinical management. Notably, the lymphoma itself may have precipitated or exacerbated the psychiatric condition, underscoring the potential for oncological diseases to manifest with rapidly progressive dementia and catatonia. A multidisciplinary approach was employed, utilizing electroconvulsive therapy (ECT) for rapid resolution of catatonia, which facilitated significant mental health improvements and clearer delineation of the oncological underpinnings. Concurrently, the patient was treated with rituximab, targeting the lymphoma. This case highlights the critical need for a comprehensive evaluation in patients presenting with psychiatric symptoms, particularly in the elderly, to uncover potential medical causes and illustrates the efficacy of ECT in managing psychiatric conditions that may overshadow or complicate concurrent medical issues.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the ileum in an adult presenting with intussusception: a case report and literature review.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (EMZL), also known as MALT lymphoma, is an extranodal multiorgan-invasive proliferative lymphoma composed of small B cells with variable morphology. It most commonly occurs in the digestive tract, with a high prevalence in the stomach, but EMZL originating in the small intestine is rare and lacks specificity in clinical manifestations, which makes it easy to be misdiagnosed. Herein, we report a rare case of small intestinal EMZL presentation as intussusception in a 32-year-old man. A colonoscopy performed at the local hospital revealed a pedicled polyp about 5 cm × 5 cm in size with a rough surface, and hyperemia was seen in the ileocecal region. He was admitted to our hospital for a polypectomy. A contrast-enhanced computed tomographic (CT) scan suggested ileocolic intussusception, which was subsequently confirmed by a colonoscopy in our hospital. Adult intussusception is relatively rare, with 90% of cases having a known causative mechanism and 40% of cases caused by primary or secondary malignancies. Therefore, we performed a laparoscopic-assisted right hemicolectomy for the patient. The resected specimen showed that the terminal ileum was intussuscepted into the ascending colon, and the intussusception was hyperemia and edema. A 2.5 cm × 2.5 cm × 1.5 cm mass was seen at the end of the intussusception. Postoperative pathology revealed that the mass was EMZL, partially transformed into a large B-cell lymphoma. The patient was transferred to the hematology department and completed a PET-CT showing postoperative manifestations of primary intestinal lymphoma, Lugano staging IE2. Although EMZL was an indolent lymphoma and the patient was in the early stages, the rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) regimen was given in view of the histological transformation. The patient is in regular follow-up. This was a rare case of small intestinal mass due to EMZL presented as intussusception in adults, which highlighted laparoscopic-assisted enterectomy as a potential therapeutic approach in the multidisciplinary collaborative therapy of small intestine EMZL.

The common variable immunodeficiency IgM repertoire narrowly recognizes erythrocyte and platelet glycans.

BACKGROUND: Autoimmune cytopenias (AICs) regularly occur in profoundly IgG-deficient patients with common variable immunodeficiency (CVID). The isotypes, antigenic targets, and origin(s) of their disease-causing autoantibodies are unclear. OBJECTIVE: We sought to determine reactivity, clonality, and provenance of AIC-associated IgM autoantibodies in patients with CVID. METHODS: We used glycan arrays, patient erythrocytes, and platelets to determine targets of CVID IgM autoantibodies. Glycan-binding profiles were used to identify autoreactive clones across B-cell subsets, specifically circulating marginal zone (MZ) B cells, for sorting and IGH sequencing. The locations, transcriptomes, and responses of tonsillar MZ B cells to different TH- cell subsets were determined by confocal microscopy, RNA-sequencing, and cocultures, respectively. RESULTS: Autoreactive IgM coated erythrocytes and platelets from many CVID patients with AICs (CVID+AIC). On glycan arrays, CVID+AIC plasma IgM narrowly recognized erythrocytic i antigens and platelet i-related antigens and failed to bind hundreds of pathogen- and tumor-associated carbohydrates. Polyclonal i antigen-recognizing B-cell receptors were highly enriched among CVID+AIC circulating MZ B cells. Within tonsillar tissues, MZ B cells secreted copious IgM when activated by the combination of IL-10 and IL-21 or when cultured with IL-10/IL-21-secreting FOXP3-CD25hi T follicular helper (Tfh) cells. In lymph nodes from immunocompetent controls, MZ B cells, plentiful FOXP3+ regulatory T cells, and rare FOXP3-CD25+ cells that represented likely CD25hi Tfh cells all localized outside of germinal centers. In CVID+AIC lymph nodes, cellular positions were similar but CD25hi Tfh cells greatly outnumbered regulatory cells. CONCLUSIONS: Our findings indicate that glycan-reactive IgM autoantibodies produced outside of germinal centers may contribute to the autoimmune pathogenesis of CVID.

Bruton's tyrosine kinase inhibition limits endotoxic shock by suppressing IL-6 production by marginal zone B cells in mice.

Sepsis is a systemic inflammatory response to a severe, life-threatening infection with organ dysfunction. Although there is no effective treatment for this fatal illness, a deeper understanding of the pathophysiological basis of sepsis and its underlying mechanisms could lead to the development of new treatment approaches. Here, we demonstrate that the selective Bruton's tyrosine kinase (Btk) inhibitor acalabrutinib augments survival rates in a lipopolysaccharide (LPS)-induced septic model. Our in vitro and in vivo findings both indicate that acalabrutinib reduces IL-6 production specifically in marginal zone B (MZ B) cells rather than in macrophages. Furthermore, Btk-deficient MZ B cells exhibited suppressed LPS-induced IL-6 production in vitro. Nuclear factor-kappa B (NF-κB) signaling, which is the downstream signaling cascade of Toll-like receptor 4 (TLR4), was also severely attenuated in Btk-deficient MZ B cells. These findings suggest that Btk blockade may prevent sepsis by inhibiting IL-6 production in MZ B cells. In addition, although Btk inhibition may adversely affect B cell maturation and humoral immunity, antibody responses were not impaired when acalabrutinib was administered for a short period after immunization with T-cell-independent (TI) and T-cell-dependent (TD) antigens. In contrast, long-term administration of acalabrutinib slightly impaired humoral immunity. Therefore, these findings suggest that Btk inhibitors may be a potential option for alleviating endotoxic shock without compromising humoral immunity and emphasize the importance of maintaining a delicate balance between immunomodulation and inflammation suppression.

Spontaneous regression and rare relapse after excisional biopsy in long-term observation of 31 patients with primary conjunctival lymphoma.

To elucidate long-term outcome in primary conjunctival lymphoma, a review was conducted of 31 consecutive patients: 21 men and 10 women with an age range of 28 to 85 (median, 61) years at presentation and follow-up periods ranging from 1 to 19 (median, 7) years. Conjunctival lymphoma was on the right side in 10 patients, on the left side in 12, and on both sides in 9. Upper, lower, or both fornix lesions in 28 patients were all diagnosed as extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), while thick nasal bulbar conjunctival lesions in 3 patients were differently diagnosed as MALT lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma, respectively. Seven patients underwent local radiation (30 Gy): as initial treatment in 5 patients and treatment for relapse in 2 patients. The remaining 24 patients were observed without additional treatment after excisional biopsy: 5 of these 24 patients showed relapse 0.5 to 6 years later and underwent excisional biopsy again that revealed MALT lymphoma. Of the 5 patients with relapse, only one with second-time relapse underwent radiation. Fluorodeoxyglucose positron emission tomography was performed in 18 patients and showed no systemic lesions: high uptake was noted in the residual conjunctival lesions of 4 patients and in the relapsed conjunctival lesions of 3 patients. One patient died of rectal cancer while no patients died of lymphoma. Observation is an option in patients with primary conjunctival lymphoma after excisional biopsy. Radiation is a treatment option in the case of relapse.

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.

Two distinct subpopulations of marginal zone B cells exhibit differential antibody-producing capacities and radioresistance.

Marginal zone (MZ) B cells, which are splenic innate-like B cells that rapidly secrete antibodies (Abs) against blood-borne pathogens, are composed of heterogeneous subpopulations. Here, we showed that MZ B cells can be divided into two distinct subpopulations according to their CD80 expression levels. CD80high MZ B cells exhibited greater Ab-producing, proliferative, and IL-10-secreting capacities than did CD80low MZ B cells. Notably, CD80high MZ B cells survived 2-Gy whole-body irradiation, whereas CD80low MZ B cells were depleted by irradiation and then repleted with one month after irradiation. Depletion of CD80low MZ B cells led to accelerated development of type II collagen (CII)-induced arthritis upon immunization with bovine CII. CD80high MZ B cells exhibited higher expression of genes involved in proliferation, plasma cell differentiation, and the antioxidant response. CD80high MZ B cells expressed more autoreactive B cell receptors (BCRs) that recognized double-stranded DNA or CII, expressed more immunoglobulin heavy chain sequences with shorter complementarity-determining region 3 sequences, and included more clonotypes with no N-nucleotides or with B-1a BCR sequences than CD80low MZ B cells. Adoptive transfer experiments showed that CD21+CD23+ transitional 2 MZ precursors preferentially generated CD80low MZ B cells and that a proportion of CD80low MZ B cells were converted into CD80high MZ B cells; in contrast, CD80high MZ B cells stably remained CD80high MZ B cells. In summary, MZ B cells can be divided into two subpopulations according to their CD80 expression levels, Ab-producing capacity, radioresistance, and autoreactivity, and these findings may suggest a hierarchical composition of MZ B cells with differential stability and BCR specificity.

Primary Cutaneous Marginal Zone Lymphoma following Repeated Inflammation Caused by Hair Dyeing.

Primary cutaneous marginal zone lymphoma (PCMZL) is a rare form of B-cell lymphoma that primarily affects the skin. Chronic antigen stimulation has been implicated in its development, with cases associated with various triggers. We present a case of PCMZL following chronic inflammation caused by long-term hair dyeing. A 75-year-old woman with a history of repeated inflammation and itching after hair dyeing for 30 years presented with persistent red-to-violaceous patches and plaques on her scalp. Despite receiving topical corticosteroid treatment for 10 years, the lesions remained. Pathological examinations confirmed the diagnosis of PCMZL. The patient achieved complete remission after radiotherapy. This case underscores the potential link between chronic inflammation and the development of PCMZL.

Unusual localization and clinical presentation of primary central nervous system extranodal marginal zone B­cell lymphoma: A case report.

Primary central nervous system (CNS) extranodal marginal zone B-cell lymphoma (MZBL) is a rare low-grade non-Hodgkin lymphoma, characterised predominantly by small B cells, plasma cells, monocytoid cells and scattered large immunoblasts. Primary CNS MZBL is a slow-growing tumour that remains localised and is characterised by an excellent clinical prognosis. The present study describes the case of a 48-year-old HIV-negative female patient with a history of head trauma 1 year prior, who presented with worsening neurological symptoms and a magnetic resonance imaging finding of a ~3-cm extra-axial mass within the left lateral ventricle. From histopathology and immunohistochemistry, the lesion was diagnosed as a CNS MZBL; as no other primary lesions were found, the base of the choroid plexuses of the left lateral ventricle was considered the primary site. To the best of our knowledge, the current case is the first study to report on primary CNS MZBL arising in this anatomical site and paves the way for further studies on the role of chronic inflammation (in the present case resulting from trauma) in the pathogenesis not only of primary CNS MZBL but also of lymphoma in general. Additionally, this report could serve as a starting point for studies analysing the role of meningothelial cells in the pathogenesis of primary CNS MZBL.

Intracranial hematolymphoid malignancies: A case series with molecular characterization.

OBJECTIVE: Central nervous system (CNS) manifestations of hematologic malignancies are uncommon and often have a poor prognosis. As hematologic neoplasms are typically chemotherapy- and radiotherapy-sensitive, surgical resection is usually not indicated; thus, opportunities for in-depth characterization of CNS hematologic tumors are limited. Here, we report four cases of rare intracranial hematologic tumors requiring surgical intervention, allowing for histopathologic and genomic characterization. METHODS: The clinical course, genetic perturbations, and histopathological features are described for a case of 1) primary marginal zone B-cell lymphoma of the dura as well as cases of brain metastases of 2) cutaneous T-cell lymphoma, 3) acute myeloid leukemia/myeloid sarcoma, and 4) multiple myeloma. Targeted DNA sequencing, fluorescence in situ hybridization, cytogenetic analysis, flow cytometry and immunohistochemical staining were used to assess the lesions. RESULT: Molecular and histopathological characterizations of four unusual presentations of hematolymphoid diseases involving the CNS are presented. Genetic abnormalities were identified in each lesion, including chromosomal aberrations and single nucleotide variants resulting in missense or nonsense mutations in oncogenes. CONCLUSIONS: Our case series provides insight into unique pathological phenotypes of hematologic neoplasms with atypical CNS involvement. We offer targets for future studies by identifying potentially pathogenic genetic variants in these lesions, as the full implications of the novel molecular abnormalities described remain unclear.

Radiological and pathological analysis of the galaxy sign in patients with pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma.

BACKGROUND: Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma sometimes presents as large pulmonary nodules composed of small nodular opacities (galaxy sign) on computed tomography (CT). The aim of this study was to assess the presence, usefulness, and pathological characteristics of the galaxy sign on CT of pulmonary MALT lymphoma. METHODS: From January 2011 to December 2021, chest CTs of 43 patients with pulmonary MALT lymphoma were reviewed by two radiologists for the galaxy sign and various other findings. Interreader agreement to characterize the galaxy sign and factors associated in making a correct first impression on CT prior to pathological diagnosis were assessed. Resected specimens were reviewed by two pathologists, and the proportion of peripheral lymphoma infiltrates was compared between lesions with and without the galaxy sign. RESULTS: Of 43 patients, 22 patients (44.2%) showed the galaxy sign (κ = 0.768, p < 0.0001). The galaxy sign (p = 0.010) was associated with making a correct first impression on CT prior to pathological diagnosis. On pathological examination, lesions showing the galaxy sign on CT demonstrated a significantly higher proportion of peripheral lymphoma infiltrates (p = 0.001). CONCLUSION: The galaxy sign can be seen on CT of pulmonary MALT lymphoma with a higher proportion of peripheral lymphoma infiltrates and may be useful in making a correct diagnosis of pulmonary MALT lymphoma.

Mediastinal Follicular Dendritic Cell Sarcoma With Underlying Sjogren's Syndrome.

Follicular dendritic cells help advance B-Cells in becoming memory B-Cells or antibody-producing plasma cells in the light zone, or undergo additional affinity maturation in the dark zone. Follicular dendritic cell sarcoma (FDCS) is an extremely rare soft tissue malignancy derived from follicular dendritic cells. Autoimmune disease increases the risks for the development of hematological malignancies. To the best of our knowledge, there are few cases of FDCS development in the setting of underlying Sjogren's syndrome (SS). Therefore, in this report, we present a novel case of FDCS associated with new-onset SS. In SS, the follicular dendritic cells are organized within germinal centers within the glands it infiltrates and is involved in B-Cell development. Because FDCS is derived from follicular dendritic cells, our report postulates that the unregulated follicular dendritic cell proliferation that may occur in SS could increase the risk for FDCS. Due to this possible connection observed in our patient, we highlight FDCS as a differential diagnosis when considering soft tissue cancers. We urge additional research to outline and explore the possible pathologic link between SS and FDCS.

Lambert-Eaton myasthenic syndrome with primary thymic marginal zone B-cell lymphoma: A case report.

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune paraneoplastic syndrome with proximal muscle weakness, that often complicates small cell lung cancer. It is known that neurological symptoms do not improve with malignancy treatment alone in many LEMS patients, therefore treatment is often difficult. Since Lambert-Eaton myasthenic syndrome is a rare disease with a frequency of about 1/100 that of myasthenia gravis, there are only a few case reports on malignancy complications other than small cell lung cancer. We report a LEMS patient in his 40s who was found to have an anterior mediastinal mass. We performed surgical resection and confirmed the diagnosis of primary thymic marginal zone B-cell lymphoma by pathological diagnosis using immunostaining. Thymectomy and malignant lymphoma treatment with rituximab had no effect on neurological symptoms. The neurological symptoms improved only after we provided comprehensive care with the haematology, neurology, and rehabilitation department.

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.

Insights into B-cell ontogeny inferred from human immunology.

Due to ontogenetic changes in B-cell developmental lineages, the mature B-cell compartment constitutes by functionally different B-cell subsets that emerged from prenatal, early postnatal or adult precursors. While negative selection processes operate primarily within the framework of B-cell tolerance checkpoints during B-cell development, further differentiation into distinct B-cell subsets is additionally induced by positive selection. In addition to endogenous antigens, contact with microbial antigens is also involved in this selection process, with intestinal commensals having a significant influence on the development of a large layer within the B-cell compartment. The decisive threshold that triggers negative selection seems to be relaxed during fetal B-cell development, thereby allowing recruitment of polyreactive and also autoreactive B-cell clones into the mature naïve B-cell compartment. Almost all of the concepts on B-cell ontogeny are based on observations in laboratory mice that not only differ from humans in their developmental timeline but also in their composition of commensal microorganisms or rather a lack of exposure to these. In this review, we summarize conceptual findings on B-cell ontogeny and particularly describe key insights into the developing human B-cell compartment and immunoglobulin repertoire formation.

[Clinical Impact Assessment and Utilization Prospects of the t(11:18) Chromosomal Translocation in Gastric MALT Lymphoma in Koreans: A Single Center Retrospective Analysis].

Background/Aims: The gastric extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (gastric MALT lymphoma) are mostly related to Helicobacter pylori infections. However, chromosomal aberration involving translocation t(11;18) is also frequently reported in these patients. Methods: The study was a retrospective review and analysis of electronic medical records to assess the factors which affect complete remission (CR) in patients with gastric MALT lymphoma. Based on the medical records, subjects with gastric MALT lymphoma were enrolled consecutively from January 2004 to December 2021. Results: Among the 77 subjects who were found with gastric MALT lymphoma in the database, 65 cases with complete records were analyzed. Of these, 66.2% (43/65) were H. pylori positive. Genetic analyses for t(11:18) were done on 41 subjects. The t(11:18) chromosomal translocation with MALT1:BIRC3 fusion was found in 31.7% (13/41) of the subjects. With H. pylori eradication therapy, 75% (21/28) of the subjects without t(11:18) achieved CR. However, only 23.1% (3/13) subjects with t(11:18) could achieve CR (p-value= 0.009). In the H. pylori-positive group, 85.7% (18/21) subjects without t(11:18) achieved CR with eradication therapy, but 71.4% (5/7) subjects with t(11:18) failed to achieve CR (p-value=0.004). In the H. pylori-negative group, 42.3% (3/7) of the subjects without t(11:18) achieved CR with eradication therapy. However, 83.3% (5/6) of H. pylori-negative subjects with t(11:18) failed to achieve CR with eradication therapy and needed additional radiotherapy (p-value=0.396). Conclusions: H. pylori negativity and the presence of t(11:18) were both risk factors for failure to achieve CR with H. pylori eradication therapy as the first line of treatment.

COVID-19 vaccination-related [18F]FDG-avid lymph node in a patient with marginal zone B-cell lymphoma.

The [18F]FDG PET/CT is a crucial tool in the diagnostic process and monitoring of neoplastic diseases. Currently, during the global program of vaccination against COVID-19 and the possibility of axillary lymphadenopathy after this injection, the correct interpretation of PET/CT images is vitally significant and may create some difficulties. We present a case of increased uptake of [18F]FDG in an axillary lymph node in a PET/CT scan performed 2 days after the Pfizer BioNTech COVID-19 vaccine in a 48-year-old patient newly diagnosed with marginal zone B-cell lymphoma.

Dural lymphoma misdiagnosed as subdural hematoma following head trauma after an episode of syncope.

Primary dural lymphoma is a rare subtype of primary central nervous system lymphoma. Primary dural lymphoma may be radiologically misdiagnosed as it shares similar imaging characteristics with several pathologies, including meningiomas and subdural or epidural hematomas. We present a patient who was originally diagnosed with a subdural hematoma following a syncopal episode on computed tomography. Follow-up magnetic resonance imaging of the brain demonstrated heterogeneously enhancing dural-based mass overlying the left frontoparietal convexity associated with bidirectional dural tails, suggestive of a malignant meningioma. Neurosurgical histopathology revealed marginal zone B-cell lymphoma. This case represents the potential difficulty in diagnosing primary dural lymphoma, especially in the setting of uncertain clinical history and obscured imaging features.

Intraparenchymal Mucosa-Associated Lymphoid Tissue Lymphoma: A Case Report.

Marginal zone B-cell lymphoma (MZBCL) of mucosa-associated lymphoid tissue (MALT) type, which is primary to the central nervous system (CNS), is a rare lesion, with those originating within the parenchyma even more so. We present the case of a 64-year-old male with weakness in the left hand and focal motor seizures of his arm, who was found to have a right frontal intraparenchymal lesion. Following resection, histopathological and immunohistochemical evaluations were completed, leading to a diagnosis of a primary CNS MZBCL of MALT type in the context of a negative workup of systemic disease. Neuroimaging, histopathological, and immunohistochemical findings, as well as a comprehensive literature review of similar cases, are discussed.

Rapid progression of marginal zone B-cell lymphoma after COVID-19 vaccination (BNT162b2): A case report.

B-cell lymphomas are neoplastic diseases occasionally associated with chronic inflammation. mRNA vaccines for coronavirus disease 2019 (COVID-19) induce inflammatory responses, which often lead to fever and lymphadenopathies indistinguishable from lymphomas. Although both lymphadenopathies and lymphomas can be influential, the correlation between them is unclear. Herein, we present the first case of marginal zone B-cell lymphoma following mRNA COVID-19 vaccination. An 80-year-old Japanese woman presented with a right temporal mass that appeared the morning after she was administered her first mRNA COVID-19 vaccination (BNT162b2). The mass gradually decreased in size but persisted over 6 weeks after her first vaccination (3 weeks after her second vaccination). At her first visit to our hospital, ultrasound revealed the size of the mass to be 28.5 × 5.7 mm, and computed tomography revealed multiple lymphadenopathies in the right parotid, submandibular, jugular, and supraclavicular regions. Initially, we suspected head-and-neck benign lymphadenopathy as a side effect of vaccination. Nine weeks later, the number of swollen submandibular and parotid glands increased, and the lymph nodes further enlarged. Finally, the right temporal mass was diagnosed as marginal zone B-cell lymphoma based on immunohistochemical and flow cytometry findings of biopsy specimens. Our findings suggest that although 4-6 weeks of observation for lymph node inflammation after the second vaccination is recommended, malignancy should also be considered in the differential diagnosis of lymphadenopathy following vaccination.