Search

Summary: Background: Emergence of SARS-CoV-2 variants that escape neutralising antibodies hampers the development of vaccines and therapeutic antibodies against SARS-CoV-2. IGHV3-53/3-66-derived public antibodies, which are generally specific to the prototype virus and are frequently induced in infected or vaccinated individuals, show minimal affinity maturation and high potency against prototype SARS-CoV-2. Methods: Monoclonal antibodies isolated from a Delta breakthrough infection case were analysed for cross-neutralising activities against SARS-CoV-2 variants. The broadly neutralising antibody K4-66 was further analysed in a hamster model, and the effect of somatic hypermutations was assessed using the inferred germline precursor. Findings: Antibodies derived from IGHV3-53/3-66 showed broader neutralising activity than antibodies derived from IGHV1-69 and other IGHV genes. IGHV3-53/3-66 antibodies neutralised the Delta variant better than the IGHV1-69 antibodies, suggesting that the IGHV3-53/3-66 antibodies were further maturated by Delta breakthrough infection. One IGHV3-53/3-66 antibody, K4-66, neutralised all Omicron subvariants tested, including EG.5.1, BA.2.86, and JN.1, and decreased the viral load in the lungs of hamsters infected with Omicron subvariant XBB.1.5. The importance of somatic hypermutations was demonstrated by the loss of neutralising activity of the inferred germline precursor of K4-66 against Beta and Omicron variants. Interpretation: Broadly neutralising IGHV3-53/3-66 antibodies have potential as a target for the development of effective vaccines and therapeutic antibodies against newly emerging SARS-CoV-2 variants. Funding: This work was supported by grants from AMED (JP23ym0126048, JP22ym0126048, JP21ym0126048, JP23wm0125002, JP233fa627001, JP223fa627009, JP24jf0126002, and JP22fk0108572), and the JSPS (JP21H02970, JK23K20041, and JPJSCCA20240006).

Abstract Circulation of SARS-CoV-2 Omicron XBB has resulted in the emergence of XBB.1.5, a new Variant of Interest. Our phylogenetic analysis suggests that XBB.1.5 evolved from XBB.1 by acquiring the S486P spike (S) mutation, subsequent to the acquisition of a nonsense mutation in ORF8. Neutralization assays showed similar abilities of immune escape between XBB.1.5 and XBB.1. We determine the structural basis for the interaction between human ACE2 and the S protein of XBB.1.5, showing similar overall structures between the S proteins of XBB.1 and XBB.1.5. We provide the intrinsic pathogenicity of XBB.1 and XBB.1.5 in hamsters. Importantly, we find that the ORF8 nonsense mutation of XBB.1.5 resulted in impairment of MHC suppression. In vivo experiments using recombinant viruses reveal that the XBB.1.5 mutations are involved with reduced virulence of XBB.1.5. Together, our study identifies the two viral functions defined the difference between XBB.1 and XBB.1.5.

Abstract Objectives This study aimed to extract endoscopic findings for diagnosing colorectal neoplasia associated with sessile serrated lesions (SSLs), which are of significant interest. Methods To compare the magnifying narrow‐band imaging (NBI) findings with microscopic morphology, we classified SSLs into two groups: Group A SSLs included the majority of uniform SSLs and any dysplasia other than that classified as group B SSLs. Group B SSLs included SSLs with intramucosal and invasive carcinoma. We also quantitatively assessed visible vessels using ImageJ software. Results This study included 47 patients with 50 group B SSLs who underwent endoscopic resection between 2012 and 2020. The results were retrospectively compared with those of 237 patients with 311 group A SSLs that underwent endoscopic resection. Using conventional white‐light endoscopy, significantly more group B SSLs had uneven shapes and some reddening compared to group A SSLs. The diagnostic odds ratios for group B SSLs were as follows: lesions with a diameter ≥10 mm, 9.76; uneven shape, 3.79; reddening, 15.46; and visible vessels with NBI, 11.32. Regarding visible vessels with NBI, the specificity and diagnostic accuracy for group B SSLs were 94.9% and 93.1%, respectively. The percentage of the vascular tonal area of NBI images was significantly larger for group B SSLs than for group A SSLs (3.97% vs. 0.29%; p < 0.01). Conclusions SSLs with reddening and/or a diameter ≥10 mm are suspected to contain cancerous components. Moreover, visible vessels observed using magnifying NBI can serve as objective indicators for diagnosing SSLs with cancerous components with a high degree of accuracy.

IntroductionThe severe acute respiratory syndrome coronavirus (SARS-CoV-2) spike (S) protein is essential in mediating membrane fusion of the virus with the target cells. Several reports demonstrated that SARS-CoV-2 S protein fusogenicity is reportedly closely associated with the intrinsic pathogenicity of the virus determined using hamster models. However, the association between S protein fusogenicity and other virological parameters remains elusive.MethodsIn this study, we investigated the virological parameters (e.g., S1/S2 cleavage efficiency, plaque size, pseudoviral infectivity, pseudovirus entry efficiency, and viral replication kinetics) of eleven previous variants of concern (VOCs) and variants of interest (VOIs) correlating with S protein fusogenicity.Results and discussionS protein fusogenicity was found to be strongly correlated with S1/S2 cleavage efficiency and plaque size formed by clinical isolates. However, S protein fusogenicity was less associated with pseudoviral infectivity, pseudovirus entry efficiency, and viral replication kinetics. Taken together, our results suggest that S1/S2 cleavage efficiency and plaque size could be potential indicators to predict the intrinsic pathogenicity and S protein fusogenicity of newly emerged SARS-CoV-2 variants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has substantially diversified during the pandemic, resulting in the successive emergence of variants characterized by various mutations. It has been observed that several epidemic variants, including those classified as variants of concern, share mutations at four key residues (L452R, T478K, E484K, and N501Y) within the receptor binding motif (RBM) region of the spike protein. However, the processes through which these four specific RBM mutations were acquired during the evolution of SARS-CoV-2, as well as the degree to which they enhance viral fitness, remain unclear. Moreover, the effect of these mutations on the properties of the spike protein is not yet fully understood. In this study, we performed a comprehensive phylogenetic analysis and showed that the four RBM mutations have been convergently acquired across various lineages throughout the evolutionary history of SARS-CoV-2. We also found a specific pattern in the order of acquisition for some of these mutations. Additionally, our epidemic dynamic modeling demonstrated that acquiring these mutations leads to an increase in the effective reproduction number of the virus. Furthermore, we engineered mutant spike proteins with all feasible combinations of the four mutations, and examined their properties to uncover the influence that these mutations have on viral characteristics. Our results provide insights into the roles these four mutations play in shaping the viral characteristics, epidemic proliferation, and evolutionary pathway of SARS-CoV-2.

Abstract In late 2022, SARS-CoV-2 Omicron subvariants have become highly diversified, and XBB is spreading rapidly around the world. Our phylogenetic analyses suggested that XBB emerged through the recombination of two cocirculating BA.2 lineages, BJ.1 and BM.1.1.1 (a progeny of BA.2.75), during the summer of 2022. XBB.1 is the variant most profoundly resistant to BA.2/5 breakthrough infection sera to date and is more fusogenic than BA.2.75. The recombination breakpoint is located in the receptor-binding domain of spike, and each region of the recombinant spike confers immune evasion and increases fusogenicity. We further provide the structural basis for the interaction between XBB.1 spike and human ACE2. Finally, the intrinsic pathogenicity of XBB.1 in male hamsters is comparable to or even lower than that of BA.2.75. Our multiscale investigation provides evidence suggesting that XBB is the first observed SARS-CoV-2 variant to increase its fitness through recombination rather than substitutions.

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of extranodal, diffuse, large B-cell lymphoma characterized by the selective growth of lymphoma cells within the lumen of small blood vessels, with no lymphadenopathy or masses. Herein, we report a cutaneous variant of IVLBCL that is rare in Asia. A healthy 73-year-old Japanese woman presented to our hospital with painful erythematous indurations and telangiectasia of the lower extremities, which was confirmed on dermoscopy. Physical examination revealed no systemic involvement, and laboratory parameters were within normal ranges. No abnormal FDG uptake was detected on 18FDG-PET/CT. Histopathological examination revealed proliferation and dilatation of blood vessels in the subcutis layer, occluded by CD20-positive atypical lymphoid cells. Thus, the patient was diagnosed with a cutaneous variant of IVLBCL without systemic symptoms. In conclusion, it is important to confirm telangiectasia using dermoscopy and perform skin biopsies in patients presenting with sudden-onset erythematous induration.

ABSTRACT HIV-1 must overcome multiple innate antiviral mechanisms to replicate in CD4+ T lymphocytes and macrophages. Previous studies have demonstrated that the apolipoprotein B mRNA editing enzyme polypeptide-like 3 (APOBEC3, A3) family of proteins (at least A3D, A3F, A3G, and stable A3H haplotypes) contribute to HIV-1 restriction in CD4+ T lymphocytes. Virus-encoded virion infectivity factor (Vif) counteracts this antiviral activity by degrading A3 enzymes allowing HIV-1 replication in infected cells. In addition to A3 proteins, Vif also targets other cellular proteins in CD4+ T lymphocytes, including PPP2R5 proteins. However, whether Vif primarily degrades only A3 proteins during viral replication is currently unknown. Herein, we describe the development and characterization of A3F-, A3F/A3G-, and A3A-to-A3G-null THP-1 cells. In comparison to Vif-proficient HIV-1, Vif-deficient viruses have substantially reduced infectivity in parental and A3F-null THP-1 cells, and a more modest decrease in infectivity in A3F/A3G-null cells. Remarkably, disruption of A3A–A3G protein expression completely restores the infectivity of Vif-deficient viruses in THP-1 cells. These results indicate that the primary function of Vif during infectious HIV-1 production from THP-1 cells is the targeting and degradation of A3 enzymes. IMPORTANCE HIV-1 Vif neutralizes the HIV-1 restriction activity of A3 proteins. However, it is currently unclear whether Vif has additional essential cellular targets. To address this question, we disrupted A3A to A3G genes in the THP-1 myeloid cell line using CRISPR and compared the infectivity of wild-type HIV-1 and Vif mutants with the selective A3 neutralization activities. Our results demonstrate that the infectivity of Vif-deficient HIV-1 and the other Vif mutants is fully restored by ablating the expression of cellular A3A to A3G proteins. These results indicate that A3 proteins are the only essential target of Vif that is required for fully infectious HIV-1 production from THP-1 cells.

Percutaneous ablation is a low-invasive, repeatable, and curative local treatment that is now recommended for early-stage hepatocellular carcinoma (HCC) that is not suitable for surgical resection. Poorly differentiated HCC has high-grade malignancy potential. Microvascular invasion is frequently seen, even in tumors smaller than 3 cm in diameter, and prognosis is poor after percutaneous ablation. Biopsy has a high risk of complications such as bleeding and dissemination; therefore, it has limitations in determining HCC tumor malignancy prior to treatment. Advances in diagnostic imaging have enabled non-invasive diagnosis of tumor malignancy. We describe the usefulness of ultrasonography, computed tomography, magnetic resonance imaging, and 18F-fluorodeoxyglucose positron emission tomography for predicting outcome after percutaneous ablation for HCC.

Fires in photovoltaic modules are caused by hot spots, which are typically monitored by thermal images. This method helps visualize the hot spot, but it is affected by the environment (solar irradiance, wind, ambient temperature) and is not reproducible. Assessing the heat dissipation of the hot cell can be used for alternative assessment of the fire risk. This method was validated by comparing the value measured by the surface potential meter and the module potential measured directly by adding a bypass measurement circuit. The substantial reverse-bias voltage caused by mismatching or partial shading (depending on the operating conditions) leads to local heat consumption of the partially shaded solar cells and potentially causes fire. The fire risk can be assessed in the worst-case conditions (ex. 1380 W/m2 solar irradiance) by non-contact measurement of the reverse-bias voltage and calculating the heat dissipation and temperature rise. This work suggested that −13 V is the criterion and was close to the known value of reverse voltage for Si cells. The current technology inspects solar cells before assembly to the module, and there is no way of inspecting in the product test or detecting after degradation that can be covered by the proposed method in this work.

Summary: Recent studies have revealed the unique virological characteristics of Omicron, particularly those of its spike protein, such as less cleavage efficacy in cells, reduced ACE2 binding affinity, and poor fusogenicity. However, it remains unclear which mutation(s) determine these three virological characteristics of Omicron spike. Here, we show that these characteristics of the Omicron spike protein are determined by its receptor-binding domain. Of interest, molecular phylogenetic analysis revealed that acquisition of the spike S375F mutation was closely associated with the explosive spread of Omicron in the human population. We further elucidated that the F375 residue forms an interprotomer pi-pi interaction with the H505 residue of another protomer in the spike trimer, conferring the attenuated cleavage efficiency and fusogenicity of Omicron spike. Our data shed light on the evolutionary events underlying the emergence of Omicron at the molecular level.

Summary: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein mediates membrane fusion between the virus and the target cells, triggering viral entry into the latter. Here, we describe a SARS-CoV-2 spike-protein-mediated membrane fusion assay using a dual functional split reporter protein to quantitatively monitor the fusion kinetics of the viral and target cell membranes in living cells. This approach can be applied in various cell types, potentially predicting the pathogenicity of newly emerging variants.For complete details on the use and execution of this protocol, please refer to Kimura et al. (2022b), Kimura et al. (2022c), Motozono et al. (2021), Saito et al. (2022a), Saito et al. (2022b), Suzuki et al. (2022), and Yamasoba et al. (2022). : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Abstract Background and Aim Percutaneous radiofrequency ablation (RFA) is a minimally invasive and curative local treatment for hepatocellular carcinoma (HCC). However, serious concerns remain regarding critical recurrences such as metastasis, dissemination, and/or seeding due to RFA. In August 2006, we introduced selective feeding artery ablation before tumor ablation to reduce the risk of critical recurrence by blocking tumor blood flow. The aim of the present study was to clarify whether feeding artery ablation before tumor ablation can reduce the risk of critical recurrence after RFA. Methods This study retrospectively analyzed 279 patients with primary, solitary, and hypervascular HCC ≤5 cm in diameter who were treated with RFA alone between April 2001 and August 2013. Critical recurrence was defined as intra‐ or extrahepatic metastasis, dissemination, or seeding that was difficult to treat radically. Results Of the 279 HCC patients, 157 patients were treated with conventional RFA alone, and 122 patients underwent RFA with prior feeding artery ablation. Although no significant differences were seen in the rates of local tumor progression‐free survival, overall recurrence‐free survival, or overall survival between a conventional RFA group and a prior feeding artery ablation group, significant differences were seen in rates of critical recurrence‐free survival and cancer‐specific survival (5‐year, 69 vs 81%, P = 0.01 and 76 vs 88%, P = 0.03, respectively). On multivariate analysis, prior feeding artery ablation, tumor diameter, and alpha‐fetoprotein were independent factors related to critical recurrence. Conclusions Feeding artery ablation before tumor ablation may reduce the risk of critical recurrence.

Abstract Background 18F-fluorodeoxyglucose (18F-FDG) uptake in hepatocellular carcinoma (HCC) is significantly associated with early recurrence and survival after curative surgical resection. However, there are no reports regarding the relationship between 18F-FDG uptake and outcomes after radiofrequency ablation (RFA). A prospective cohort study was conducted to evaluate the prognostic value of 18F-FDG positron emission tomography (PET) in HCC patients after RFA. Methods A total of 121 consecutive patients with primary HCC (≤3 tumors, of diameter ≤ 3 cm) without vascular invasion on imaging were examined by 18F-FDG-PET computed tomography prior to RFA. An HCC with a component of 18F-FDG uptake visibly stronger than that of surrounding liver was defined as 18F-FDG-PET positive. Results The median follow-up period was 1267 days. There were 110 18F-FDG-PET negative and 11 positive tumors. The cumulative 1-year recurrence rates in the 18F-FDG negative and positive groups were 30 and 64% (P = 0.017), respectively, and cumulative 1-year metastatic recurrence rates were 6 and 36% (P

Abstract Background and Aim Portosystemic shunt occlusion using endovascular treatment can transiently improve liver function in patients with decompensated cirrhosis. In recent years, viral hepatitis can be easily controlled. The present study aimed to clarify the safety and efficacy of endovascular treatment in decompensated cirrhotic patients, and to elucidate whether viral treatment improves the prognosis after shunt occlusion. Methods Among 98 cirrhotic patients who received portosystemic shunt occlusion from January 2007 to June 2016, we retrospectively analyzed 61 decompensated cirrhotic patients. Results Forty‐five patients had viral hepatitis. Recovery rates of liver function to Child A within 6 months in viral hepatitis, non‐viral hepatitis, and overall were 78% (35/45), 81% (13/16), and 79% (48/61), respectively. Recovery rates according to baseline Child‐Pugh score were as follows: score 7, 88% (15/17); score 8, 89% (24/27); score 9, 69% (9/13); and score ≥ 10, 0% (0/4). Three‐year reprogression rates to decompensated cirrhosis for non‐virus, non‐sustained viral negativity (SVN), and SVN groups were 23 100, and 0%, respectively (P

The introduction of combination antiretroviral therapy (cART) has managed to control the replication of human immunodeficiency virus type 1 (HIV-1) in infected patients. However, a complete HIV-1 cure, including a functional cure for or eradication of HIV-1, has yet to be achieved because of the persistence of latent HIV-1 reservoirs in adherent patients. The primary source of these viral reservoirs is integrated proviral DNA in CD4+ T cells and other non-T cells. Although a small fraction of this proviral DNA is replication-competent and contributes to viral rebound after the cessation of cART, >90% of latent viral reservoirs are replication-defective and some contain high rates of G-to-A mutations in proviral DNA. At least in part, these high rates of G-to-A mutations arise from the APOBEC3 (A3) family proteins of cytosine deaminases. A general model has shown that the HIV-1 virus infectivity factor (Vif) degrades A3 family proteins by proteasome-mediated pathways and inactivates their antiviral activities. However, Vif does not fully counteract the HIV-1 restriction activity of A3 family proteins in vivo, as indicated by observations of A3-mediated G-to-A hypermutation in the proviral DNA of HIV-1-infected patients. The frequency of A3-mediated hypermutation potentially contributes to slower HIV-1/AIDS disease progression and virus evolution including the emergence of cytotoxic T lymphocyte escape mutants. Therefore, combined with other strategies, the manipulation of A3-mediated mutagenesis may contribute to an HIV-1 functional cure aimed at cART-free remission. In this mini-review, we discuss the possibility of an HIV-1 functional cure arising from manipulation of A3 mutagenic activity.

Background: Recently, medial patellofemoral ligament (MPFL) reconstruction has become a common, widely used procedure to treat patellar instability. However, few reports exist on the long-term outcome after MPFL reconstruction. We elucidated the middle- to long-term outcome after MPFL reconstruction with Insall’s proximal realignment. Methods: From 1999 to 2012, 42 knees of 32 patients who underwent MPFL reconstruction with Insall’s proximal realignment were reviewed with a minimum follow-up of five years. Patients who could visit our office and receive some designated examinations were included in this study. The re-dislocation rate and patellar apprehension sign postoperatively were evaluated. The Kujala score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were calculated. We assessed the images using plane x-ray and magnetic resonance imaging (MRI). The tilting angle (TA), congruence angle (CA), and lateral shift ratio (LSR) on the plane x-ray were measured pre- and postoperatively and at final follow-up. Using MRI, osteochondral lesions at the patellofemoral joint were evaluated. Results: A total of 20 knees of 15 patients (two male, 13 female) who could visit our office were studied. The follow-up rate was 47.6%. The mean age at operation was 19.9 (11–41) years and mean follow-up was 123 (60–215) months. One knee (5.5%) had a history of postoperative subluxation, and five (25%) had a positive apprehension sign. The mean Kujala score significantly improved from 65.5 to 86.1 points (P

Herein we disclose the radical cation Diels–Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including “direct” and “indirect”, are possible to construct the Diels–Alder adduct.

Background/AimsAlthough daclatasvir with asunaprevir was approved in Japan for interferon ineligible or intolerant patients, patients aged ≥75 years were excluded in the phase III trial. The present study aimed to evaluate the safety and efficacy of this therapy for elderly patients aged ≥75 years and to clarify whether an extremely high sustained virological response (SVR) rate can be achieved, even in a real-world setting when patients with resistance-associated substitutions (RASs) to nonstructural protein 5A (NS5A) inhibitors or prior simeprevir failure are excluded.Methods : Daclatasvir (60 mg) and asunaprevir (100 mg) were orally administered daily for 24 weeks. Patients without pre-existing NS5A RASs and simeprevir failure were enrolled in this study.Results : Overall, 110 patients were treated. The median age was 73 years old. The SVR rates of total patients, those aged ≥75 years, and those aged

Background/AimsThe present study aimed to evaluate the safety and efficacy of simeprevir-based triple therapy with reduced doses of pegylated interferon (PEG-IFN) and ribavirin for interferon (IFN) ineligible patients, such as elderly and/or cirrhotic patients, and to elucidate the factors contributing to a sustained virologic response (SVR).Methods : One hundred IFN ineligible patients infected with genotype 1b hepatitis C virus (HCV) were treated. Simeprevir (100 mg) was given orally together with reduced doses of PEG-IFN-α 2a (90 μg), and ribavirin (200 mg less than the recommended dose).Results : The patients’ median age was 70 years, and 70 patients were cirrhotic. Three patients (3%) discontinued treatment due to adverse events. The SVR rate was 64%. Factors that significantly contributed to the SVR included the γ-glutamyl transferase and α-fetoprotein levels, interleukin-28B (IL28B) polymorphism status, and the level and reduction of HCV RNA at weeks 2 and 4. The multivariate analysis showed that the IL28B polymorphism status was the only independent factor that predicted the SVR, with a positive predictive value of 77%.Conclusion : sSimeprevir-based triple therapy with reduced doses of PEG-IFN and ribavirin was safe and effective for IFN ineligible patients infected with genotype 1b HCV. IL28B polymorphism status was a useful predictor of the SVR.

Human errors of train drivers may cause serious damage. Therefore, research on human error prevention has been conducted by many researchers. In this context, brain activity measurement of train drivers using Near-infrared Spectroscopy (NIRS) has been conducted to monitor the condition of train drivers. In this study, we developed a compact wireless wearable NIRS that can be used in natural environments. The wearable NIRS has been used to measure train drivers brain function using a train driving simulator. Experimental results showed that brain activity of DLPFC increased when the driver made braking operation. The experiment for train driving with an accidental event was carried out to evaluate the relation between driver's attention and the brain activity. As a result, there was a difference in brain activity between with and without prior notice. Results showed that the increased attention of the train driver can be appeared in NIRS signal from the outer part of prefrontal cortex.

The aim of this study was to investigate a cell delivery system for repair of severe chronic osteochondral defects using magnetically labeled mesenchymal stem cells (m-MSCs), with the aid of an external magnetic device, through the accumulation of a small number of m-MSCs into a desired area and to detect the suitable number of autologous m-MSCs needed for repair of the defect. Twenty-six male Japanese white rabbits aged 6 months were used. An osteochondral defect was created bilaterally at the weight-bearing surface of the medial femoral condyle of the rabbits' knees (3 mm diameter; 4 mm depth). At 4 weeks after creation of the defect, autogenic transplantation of the m-MSCs into the defect area was performed, followed by 10-min exposure to an external magnetic device, where animals were divided into four groups: high (1 × 10 6 m-MSCs), medium (2 × 10 5 m-MSCs), low (4 × 10 4 m-MSCs), and control (PBS injection). At 4 and 12 weeks posttransplantation of m-MSCs, repaired tissue was assessed histologically using the Fortier score with toluidine blue staining. Transplantation of a low number of m-MSCs was not enough to improve osteogenesis and chondrogenesis, but the medium and high groups improved repair of the chronic defect with chondrogenic tissues and showed histologically significantly better results than the control and low groups. The use of a magnetic targeting system for delivering m-MSCs has the potential to overcome the clinical hurdles for repair of the severe chronic osteochondral defect. Furthermore, this system is predicted to produce good clinical outcomes for humans, not only to repair osteochondral defects but also to repair a variety of damaged tissues.

Objective: Rare coexistence of disease or pathology Background: Fluid overload-associated large B-cell lymphoma (FO-LBCL) is a recently described malignant lymphoma that presents with serous effusions in the pleura, peritoneum, and/or pericardium but without an identifiable lymphoma mass. This report describes the case of an 80-year-old man who presented with a pleural effusion and describes the approach to diagnosis and management of FO-LBCL. Case Report: We present a case of an 80-year-old man who presented with right pleural effusion and shortness of breath at work. Initial radiological assessment suggested a pleural effusion on the right side, without an identifiable mass, given the patient’s symptoms and imaging characteristics. Subsequently, he underwent a pleural fluid puncture and biopsy. Based on the initial pathological assessment, malignant lymphoma, a non-epithelial tumor, was considered likely, but differentiation from reactive proliferative cells was difficult, given the patient’s symptoms and cytologic characteristics. Postoperatively, histopathological examination and immunohistochemistry confirmed a diagnosis of FO-LBCL. After 1 year of follow-up, the condition had progressed and the patient died due to recurrence. Conclusions: This report has presented a case of FO-LBCL in an elderly man with pleural effusion and described how this rare and recently described lymphoma was diagnosed and managed. [ABSTRACT FROM AUTHOR]