Large B-cell lymphoma(LBCL),formerly known as diffuse large B-cell lymphoma(DLBCL),is the most common type of lymphoma,characterized by high invasiveness and strong heterogeneity.The World Health Organ-ization(WHO)lymphoma classification has been continually updated to better differentiate the biological behaviors of various subtypes of DLBCL.These updated classifications are increasingly important for prognosis stratification and treatment decisions for oncologists.The increasingly refined classification of DLBCL will inevitably require pathologists to make more precise diagnoses.Furthermore,the advances and growing diversity in lymphoma treatment also create a demand for precision diagnosis in LBCL,including therapy-target evaluation.Based on our own experience,we have systematically reviewed and summarized the current knowledge and progress in precision diagnosis of LBCL.This re-view aims to emphasize the importance of precision diagnosis in LBCL,help readers understand the relevant concepts more comprehensively and accurately,and promote the adoption of more reasonable diagnostic procedures.

EBER in-situ hybridization detection technology is a method used to detect the expression and localiza-tion of RNA molecules in tissuess and cells.Standardized detection is fundamental to ensuring the accuracy of the re-sults.To address key issues in the clinical application of EBER in-situ hybridization detection technology,Pathological Technical Expert Group of Medical Technician Committee of Chinese Medical Doctor Association,Standardization De-partment of China Association of Pathology Equipment,Pathological Technology Group of Pathological Committee of China Anti-cancer Association,and Pathological Technology Group of Pathology Committee of Chinese Research Hospi-tal Association organized experts from related fields to conduct in-depth discussions and reached this consensus.This consensus covers aspects such as the principle of EBER in-situ hybridization detection technology,sample processing standards,standards operating procedures,and quality control protocols.It aims to provide guidance for clinical labora-tories to carry out EBER in-situ hybridization detection,as well as improving the accuracy and reliability of detection results.

Purpose To investigate the clinicopathological features and prognosis of adult large B-cell lymphoma with IRF4 rearrangement(LBCL-IRF4r).Methods Clinical data of 63 adult LBCL-IRF4r cases were collected.The EnVision two-step method was employed for immunohistochemical staining,and fluorescence in situ hybridization was used to detect rearrangements or deletions of the IRF4,BCL2,MYC,BCL6,and TP53 genes.The relationship be-tween clinicopathological features and prognosis was analyzed and compared with data from 132 adult non-specified dif-fuse large B-cell lymphoma(DLBCL)cases.Results Among the 63 adult LBCL-IRF4r patients,the male to female ratio was 1.1∶1,with a median age of 54.0 years(range 20-84 years),and 14 cases(22.2％)were＜40 years old,24 cases(38.1％)were between 40 and 60 years old,and 25 cases(39.7％)were＞60 years old.18 cases(28.6％)were involved in Waldeyer's ring,along with 8 cases(12.7％)in cervical lymph nodes,7 cases(11.1％)in other lymph nodes and lymphatic organs,13 cases(20.6％)in stomach,4 cases(6.4％)in intestine,and 13 cases(20.6％)in other extranodal sites.63 cases showed IRF4 rearrangements,with no BCL2 and MYC translocations(0/58),30.9％(17/55)had BCL6 translocations,and 16.3％(8/49)had TP53 deletions.59 pa-tients were followed up for a median of 28 months(range 1-65 months).48 patients(81.4％)achieved complete re-sponse,10 patients(16.9％)experienced disease progression or relapse,and 3 patients(5.1％)died.Univariate a-nalysis showed that lactate dehydrogenase level,Ann Arbor stage,international prognostic index(IPI)score,growth pattern,Hans classification,and double expression of BCL2 and C-MYC were significantly associated with progression-free survival.Age,Ann Arbor stage,and IPI score were significantly associated with overall survival.Multivariate Cox regression analysis showed that double expression of BCL2 and C-MYC was an independent prognostic factor for pro-gression-free survival.Adult LBCL-IRF4r had significantly higher complete response rate and progression-free survival than adult DLBCL.Conclusion LBCL-IRF4r occurs in adults of all age groups,commonly affecting Waldeyer's ring,cervical lymph nodes,and gastrointestinal tract,and has a favorable clinical prognosis.

Purpose To explore the clinicopathological features and potential clinical value of marginal zone lym-phoma(MZL)derived from T-bet positive memory B cell.Methods Clinical data of 67 cases of MZL were collected.Hematoxylin-eosin,immunohistochemistry,and multiple immunofluorescence stains,B cell receptor high throughput sequencing technology were used to study the histology,immunophenotype,and immunoglobulin heavy chain variable gene(IGHV)repertoire.Results T-bet was expressed in some MZL patients(34/67,50.75％),which was correla-ted with clinicopathological characteristics such as gender,clinical stage,and Ki67 proliferation index(P＜0.05),and also the progression-free survival was poor(P=0.012 2).T-bet positivity was a risk factor affecting the progres-sion of MZL.Microscopically,T-bet positive MZL frequently presented T-bet positive tumor B cells surrounded follicu-lar germinal center,"MALT ball"-type lymphoepithelial lesions,and IgG positive neoplastic plasma cells(P＜0.05).T-bet had no biased influence on the VH gene usage(P＞0.05).The common VH families were IGHV4 and IGHV3,and the segments were IGHV4-34 and IGHV3-30.The positivity of T-bet was associated with somatic hypermutation(SHM)state(P=0.014 9).The SHM was mainly in the range of 2％-4.9％in T-bet positive MZL,while in T-bet negative MZL the SHM was mostly greater than 5％.The VH gene usage was not correlated with the clinicopathological features of patients(P＞0.05).IGHV4 was correlated with progression-free survival in T-bet positive MZL(P=0.038 2).Conclusion The expression of T-bet in MZL is closely related to the clinicopathological features such as histology,plasma cell immunophenotype and IGHV gene repertoire,and the prognosis of patients is poor,which may be a potential molecular marker affecting the progression of MZL.

Purpose To explore the clinicopathological features of EBV-positive nodal T-and NK-cell lymphoma.Methods Clinical and pathological data of 5 cases were collected.The expression of CD3,CD56,TIA-1,Granzyme B and other markers were detected by immunohistochemistry.The expression of EBER was detected by in situ hybrid-ization.The gene rearrangement and clonality were analyzed by PCR and polyacrylamide gel electrophoresis.The litera-tures were reviewed.Results The primary lesions of the 5 patients were all located in lymph nodes.All patients pres-ented with multiple lymphadenopathy,B symptoms,elevated lactate dehydrogenase(LDH)and C-reactive protein(CRP),and were in stage Ⅲ/Ⅳ.Histopathologically,the lesions show a diffuse infiltration of large to medium monot-onous tumor lymphocytes.Cell apoptosis,necrosis,and vascular invasion were not significant.Tumor cells of all cases were positive for CD3 but negative for CD56.All cases were positive for the cytotoxic markers.In situ hybridization de-tection showed that the majority of tumor cells were diffusely positive for EBER.Nevertheless,only 4 cases were posi-tive for TCR gene clonal rearrangement.Three patients received chemotherapy,2 patient declined the treatments.The median overall survival was only 3 months.Conclusions EBV-positive nodal T-and NK-cell lymphoma is an EBV-positive lymphoma of cytotoxic T-or NK-cell lineage presenting primarily with nodal disease,which is more common in elderly males.The patient has obvious symptoms and signs,rapid disease progression,and poor prognosis.Under-standing the clinicopathological features of EBV-positive nodal T-and NK-cell lymphoma can help differentiate it from other EBV-positive T-and NK-cell lymphoid proliferations and lymphomas.

Purpose This study aims to analyze the clinical,pathological,and molecular genetic characteristics of nodal follicular helper T-cell lymphoma,follicular type(nTFHL-F).Methods 7 cases of nTFHL-F were re-viewed.Clinical data were collected,tissue morphology was summarized,and immunohistochemical staining and mo-lecular testing were performed.Results The median age of patients was 62 years with a male-to-female ratio of 6:1.The initial symptoms included neck lymphadenectasis in 6 cases and abdominal discomfort in one.Six cases were in ad-vanced stages,while 1 case was in the localized stage.The tumors exhibited a vague,irregular follicular nodular pat-tern,without significant polymorphic inflammatory background or high endothelial vascular proliferation.Five cases showed a progressive transformation resembling germinal center pattern,and two cases exhibited a follicular lymphoma-like growth pattern.Tumor cells presented three distinct morphologies:centrocyte-like appearance,monocytoid B cell-like appearance,and atypical cells with abundant,transparent cytoplasm.Tumor cells expressed at least three follicu-lar T-cell markers.Testing for ITK::SYK gene fusion was negative in all cases(0/7).Next generation sequencing i-dentified mutations in TET2 gene in two cases(2/2),the RHOA gene in one case(1/2),and VAV1 gene in one case(1/2).The follow-up duration ranged from 2 to 64 months,with three deaths(3/7),and a median survival time of 37 months.Conclusion nTFHL-F predominantly occurs in middle-aged to elderly males,presenting with advanced clinical stages,and has a poor prognosis.nTFHL-F is closely associated with nodal follicular helper T-cell lymphoma,angioimmunoblastic type,and mya coexist within the same individual.

Purpose To investigate the clinicopathological features and differential diagnosis of anaplastic large-cell lymphoma(ALCL)with the small cell variant.Methods The clinical data of 15 cases of small cell variant of ALCL were retrospectively analyzed.Hematoxylin-eosin staining,immunohistochemistry,EBER in situ hybridization,TCR and IgG rearrangement were performed.The clinicopathological features,prognosis and differential diagnosis were summarized with review of the literature.Results Among the 15 cases of small cell ALCL,5 were females and 10 were males,with a male-to-female ratio of 2:1.Among the 15 cases of small cell ALCL,14 were systemic ALCL[(12 cases of ALK+),and the age range was 5-63 years old(median age 20 years);There were 2 cases of ALK(-),aged more than 60 years],and 1 case of ALCL of primary cutaneous ALK(-).Microscopic features were dominated by small to medium-sized tumor cells,with irregular nuclear membranes,inconspicuous nucleoli,and a lack of or few iconic large cells.Immunohistochemically:3 cases were ALK-negative and 12 cases were ALK-positive.Tumor cells were CD30 positive in 14/15 cases,CD3 positive in 7/15 cases,CD2 positive in 2/6 cases,CD4 positive in 5/11 cases,CD5 positive in 2/8 cases,CD7 positive in 4/6 cases,CD8 positive in 1/8 cases,TIA-1 positive in 7/7 cases,Granzyme B positive in 4/6 cases and EMA positive in 6/7 cases.CD20 was negative in all cases.Immuno-globulin IgG and TCR gene rearrangement were negative in case 4 and case 11.Case 13 was positive for TCR rear-rangement and negative for immunoglobulin IgG.Twelve of the 15 patients were followed up for 0.7-165 months(me-dian,7 months),3 patients were lost to follow-up and 7 patients died.Conclusion Small cell variant ALCL is easily misdiagnosed as an inflammatory or infectious disease.A group of antibodies,including CD30 and ALK,should be routinely used in routine work,especially in young patients with systemic symptoms and leukemia manifestations or in small biopsies,to reduce misdiagnosis and missed diagnosis.

Purpose To investigate the clinical and pathological characteristics of synchronous multiple primary malignancy(sMPM)with lymphoid hematopoietic tissue tumors.Methods A retrospective analysis was conducted on the clinical and pathological data of 20 cases of sMPM associated with lymphoma.Immunohistochemistry using the En-Vision two-step method was performed to detect the expression of relevant proteins,while FISH and next-generation se-quencing technologies were used to identify gene mutations.Relevant literature was also reviewed.Results There were 14 females and 6 males,aged from 30 to 75 years(median 67 years).All of them manifested as solid organ mas-ses complicated by lymphadenopathy.Lymphohematopoietic tissue tumors consisted of:7 cases of Hodgkin lymphoma(6 cases of classic Hodgkin lymphoma,1 case of nodular lymphocyte predominant Hodgkin lymphoma),13 cases of non-Hodgkin lymphoma(4 cases of Follicular lymphoma,2 cases of small lymphocytic lymphoma/chronic lymphocytic leukemia,2 cases of diffuse large B-cell lymphoma,1 case of plasmablastic plasmacytoma,1 case of marginal zone B-cell lymphoma,1 case of B-lymphoblastic lymphoma,2 cases of peripheral T-cell lymphoma,NOS).Solid tumors con-sisted of:9 cases of papillary thyroid carcinoma,1 case of medullary thyroid carcinoma,2 cases of adenocarcinoma of the lung,2 cases of gallbladder adenocarcinoma,2 cases of invasive carcinoma of the breast,2 cases of gastrointestinal adenocarcinoma,1 case of pleomorphic undifferentiated sarcoma of the lower extremity,and 1 case of oropharyngeal squamous cell carcinoma.17 patients underwent surgical resection,and 3 patients were diagnosed by core needle biop-sy or excision biopsy.10 cases of lymphoma involved in the lymph nodes of the tumor drainage area,and 10 cases were found to have lymph node involvement in other areas by imaging examination.Among the 5 cases analyzed by targeted next generation sequencing,no revelent genetic changes were founded,and no germline mutations or chromosomal kar-yotype abnormalities were founded.Based on the tumor types,patients received varying degrees of radiotherapy,chem-otherapy,or follow-up.Follow-up information was available in all cases and ranged from 5 to 96 months,15 were sur-vived and four patients died of the tumor,and 1 case was lost to follow-up.Conclusion MPMs with lymphoid hemato-poietic tissue tumors are rare,clinicians and pathologists should be careful to avoid missing the diagnosis of lymphoma.

The morphological variations of lymphoma cells are diverse,serving as a crucial basis for pathologists to diagnose and classify different types of lymphoma.Morphology represents the external manifestations,while genetic var-iation is one of the key factors determining these morphological changes.Some morphological alterations often hint at the underlying patterns of genetic variation.Unveiling the connections between these morphological features and genetic variations can offer novel insights for lymphoma pathological diagnosis,prediction of biological behavior,and treatment selection.

Interferon regulatory factor 4(IRF4)plays an important role in B-cell development and differentiation.Large B-cell lymphoma with IRF4 gene rearrangement(LBCL-IRF4)is a germinal center derived mature B-cell lym-phoma,initially classified as a special provisional type of follicular lymphoma.With advancing research and under-standing,LBCL-IRF4 has been shown to differ from classic follicular lymphoma(cFL),pediatric follicular lymphoma(PTFL)and diffuse large B-cell lymphoma(DLBCL).The latest fifth edition of the World Health Organization(WHO)classification of hematopoietic and lymphoid tissue tumors has officially classified this tumor as a distinct type under large B cell lymphoma.To gain a more comprehensive understanding of this tumor,this paper reviews the re-search progress on the clinicopathological and molecular genetic characteristics of LBCL-IRF4.