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Evaluation of B-cell clonality can be challenging in the interpretation of lymphoid infiltrates on tissue sections. Clonality testing based on IG gene rearrangements analysis by PCR (IG-PCR) is the gold standard. Alternatively, B-cell clonality can be assessed by the recognition of immunoglobulin light chain (IgLC) restriction, by immunohistochemistry (IHC), chromogenic in situ hybridization (ISH) or flow cytometry (FC). IG-PCR requires molecular facilities, and FC requires cell suspensions, both not widely available in routine pathology units. This study evaluates the performance of B-cell clonality detection by IgLC-RNAscope® (RNAsc) in a group of 216 formalin-fixed, paraffin-embedded samples including 185 non-Hodgkin B-cell lymphomas, 11 Hodgkin lymphomas (HL) and 20 reactive samples. IgLC-RNAsc, performed in parallel with FC in 53 cases, demonstrated better performances (93% vs 83%), particularly in diffuse large B-cell lymphoma (98% vs 71%) and follicular lymphoma (93% vs 83%) diagnosis. IgLC-RNAsc was also superior to IHC and ISH especially in samples with limited tumor cell content, where IG-PCR was not informative. Performed for the first time on mediastinal lymphomas, IgLC-RNAsc identified monotypic IgLC transcripts in 69% of primary mediastinal large B-cell lymphoma (PMBCL) and 67% of mediastinal gray zone lymphomas (MGZL). IGK/L double-negative cells were detected in 1 PMBCL, 2 MGZL, and all classical HL, while monotypic IgLC expression appeared to be a hallmark in nodular lymphocyte-predominant HL. IgLC-RNAsc demonstrates to be a powerful tool in B-cell lymphoma diagnosis, above all in challenging cases with limited tumor cell content, ensuring in situ investigations on mechanisms of Ig regulation across lymphoma entities. [ABSTRACT FROM AUTHOR]

Tonsillar marginal zone hyperplasia may mimic mucosa-associated lymphoid tissue lymphoma, a rare diagnosis in children. Histologically, both entities can demonstrate expansion of the marginal zone with disruption of follicular architecture. However, marginal zone hyperplasia may appear polyclonal by flow cytometry. We present two pediatric tonsillectomy cases with tonsillar marginal zone hyperplasia and discuss the diagnostic challenges this poses in the pediatric population. Both tonsillectomies demonstrated expansion of marginal zones with partial architectural effacement, and flow cytometric analysis of both cases detected lambda light chain restricted, CD20(bright) B cells without CD38. Authors have suggested that the lambda restricted B cells in this setting represent naïve, unmutated B cells with preferential, but polyclonal, lambda expression. Our cases are in line with this thought. While robust, BIOMED-2 primer PCR can show dominant IgK peaks, which may be misinterpreted. This presents a diagnostic pitfall in the workup of pediatric tonsils that community pathologists must consider., Competing Interests: None declared., (Published by Oxford University Press and JSCR Publishing Ltd. © The Author(s) 2024.)

Multiparametric flow cytometry is a powerful diagnostic tool that permits rapid assessment of cellular antigen expression to quickly provide immunophenotypic information suitable for disease classification. This chapter describes a general approach for the identification of abnormal lymphoid populations by flow cytometry, including B, T, NK, and Hodgkin lymphoma cells suitable for the clinical and research environment. Knowledge of the common patterns of antigen expression of normal lymphoid cells is critical to permit identification of abnormal populations at disease presentation and for minimal residual disease assessment. We highlight an overview of procedures for processing and immunophenotyping non-Hodgkin B- and T-cell lymphomas and also describe our strategy for the sensitive and specific diagnosis of classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and T-cell/histiocyte-rich large B-cell lymphoma., (© 2025. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Monoclonal gammopathy (MG) causes various nephropathies, which may suffice for cytoreductive therapy even in the absence of diagnostic criteria for multiple myeloma or B-cell non-Hodgkin lymphoma. The aim of this study was to better understand the significance of light chain (LC) restriction or crystals (LC-R/C) in proximal tubules in the spectrum of LC-induced nephropathies. A consecutive cohort of 320 renal specimens with a history of B-cell dyscrasia was characterized. Special attention was paid to immunohistochemical LC restriction in proximal tubules, tubular crystals or constipation, and ultrastructural findings. Complementary cell culture experiments were performed to assess the role of LC concentrations in generating LC restriction. Light chain restriction or crystals in proximal tubules was found in a quarter of analyzed cases (81/316) and was associated with another LC-induced disease in 70.4% (57/81), especially LC cast-nephropathy (cast-NP) and interstitial myeloma infiltration. LC restriction without significant signs of acute tubular injury was observed in 11.1% (9/81). LC-R/C was not associated with inferior renal function compared to the remainder of cases, when cases with accompanying cast-NP were excluded. Besides crystals, cloudy lysosomes were significantly associated with LC-R/C on an ultrastructural level. In summary, LC-R/C is frequent and strongly associated with cast-NP, possibly indicating that a high load of clonal LC is responsible for this phenomenon, supported by the observation that LC restriction can artificially be generated in cell culture. This and the lack of significant tubular injury in a subgroup imply that in part LC-R/C is a tubular trafficking phenomenon rather than an independent disease process.

Light-chain restricted hematogones (LCR HGs) detected by flow cytometry (FC) may, occur in bone marrow mimicking involvement by a B-cell lymphoma. This phenomenon can present a diagnostic pitfall and negatively impact patient management, and may occur in other organs, including lymph nodes, For this reason, it is recommended to utilize, in case of LCR in lymph node, one additional morphological, phenotypical or molecular criteria for the diagnosis of lymphoma on cytological samples.

Evaluation of B-cell clonality can be challenging in the interpretation of lymphoid infiltrates on tissue sections. Clonality testing based on IG gene rearrangements analysis by PCR (IG-PCR) is the gold standard. Alternatively, B-cell clonality can be assessed by the recognition of immunoglobulin light chain (IgLC) restriction, by immunohistochemistry (IHC), chromogenic in situ hybridization (ISH) or flow cytometry (FC). IG-PCR requires molecular facilities, and FC requires cell suspensions, both not widely available in routine pathology units. This study evaluates the performance of B-cell clonality detection by IgLC-RNAscope® (RNAsc) in a group of 216 formalin-fixed, paraffin-embedded samples including 185 non-Hodgkin B-cell lymphomas, 11 Hodgkin lymphomas (HL) and 20 reactive samples. IgLC-RNAsc, performed in parallel with FC in 53 cases, demonstrated better performances (93% vs 83%), particularly in diffuse large B-cell lymphoma (98% vs 71%) and follicular lymphoma (93% vs 83%) diagnosis. IgLC-RNAsc was also superior to IHC and ISH especially in samples with limited tumor cell content, where IG-PCR was not informative. Performed for the first time on mediastinal lymphomas, IgLC-RNAsc identified monotypic IgLC transcripts in 69% of primary mediastinal large B-cell lymphoma (PMBCL) and 67% of mediastinal gray zone lymphomas (MGZL). IGK/L double-negative cells were detected in 1 PMBCL, 2 MGZL, and all classical HL, while monotypic IgLC expression appeared to be a hallmark in nodular lymphocyte-predominant HL. IgLC-RNAsc demonstrates to be a powerful tool in B-cell lymphoma diagnosis, above all in challenging cases with limited tumor cell content, ensuring in situ investigations on mechanisms of Ig regulation across lymphoma entities., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Follicle center lymphomas, including primary cutaneous follicle center lymphoma (PCFCL), may rarely show plasmacytic differentiation. Such cases can pose a diagnostic challenge and can be mistaken for other lymphomas that more commonly include plasma cells. Here, we report four cases of PCFCL and one case of systemic follicular lymphoma involving the skin with associated monotypic plasma cells, including the clinical, morphologic and immunophenotypic features. [ABSTRACT FROM AUTHOR]

Background: Chronic lymphocytic leukemia is a malignancy of mature B cells where there is progressive accumulation of leukemic cells. The genetic factors have been found to play a role, deletions of the long arm of chromosome 13, specifically involving band 13q14 (del(13q14)), represent the single most frequently observed cytogenetic aberration in CLL, followed by trisomy 12,del 11q22, del 6q21, del 17p13, and 14q. Objectives: To detect the structural abnormalities on chromosome 12 (trisomy 12 in patients with CLL by using FISH technique; To investigate the relation of this chromosomal abnormalities with with the expression of CD38 and light chain restriction .Patients, Materials and Methods: 1. This cross-sectional study was conducted from February 25, 2018 to December 15, 2019. Fifty newly diagnosed adult patients with CLL were enrolled in this study. 2. Each patient was assessed at the time of admission, full clinical and laboratory data were obtained from patient’s hospital records. Three ml of fresh blood sample were taken from each patient at admission. Upon confirmation of CLL diagnosis, samples were taken to FISH unit for blood preparation which includes two steps in two days, the first day to separate lymphocyte cells from another component of blood and second-day washing samples and stored till slide preparation. Slide preparation done in the 1st day and using dual color gene probe and slide reading in the second day by fluorescent microscope. The collected data were computerized and statistically analyzed using the SPSS program (Statistical Package for Social Science) version 23.Result: The median age of the patients was 64 years and the range was 45-76 years. Among 50 patients studied, 18 patients were females, representing (36%) and 32 patients were males representing (64%). Male: female ratio 1.8:1. Trisomy chromosome12 was found 15 out of 50 patients with CLL, representing 30%.Conclusion:1.In the current study,15 out of 50 CLL patients (30%)present with trisomy chromosome 12 in a sample of Iraqi adult CLL patients.2. trisomy CH 12 patients show significant relation with light chain restriction . [ABSTRACT FROM AUTHOR]

In this paper, we introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment. For lymphocyte isolation, an endoscopically harvested specimen and 5 mL of normal saline solution were placed in a wire mesh strainer set in a porcelain bowl. To obtain the lymphocyte suspension, the solid specimen was crushed using the rubber portion of a plunger of a 10 mL injection syringe. Flow cytometry was performed using the lymphocyte suspension. For validating our methods, the one-step lymphocyte isolation technique was used to perform flow cytometry on samples from 23 patients with (n = 12) or without (n = 11) gastrointestinal lymphoma. Flow cytometry of light chain expression was performed in all patient samples (feasibility: 100%). Sensitivity was 83.3% (10/12) and specificity was 100% (11/11). In conclusion, lymphocytes isolated from a single endoscopic biopsy specimen using our simplified and quick procedure are suitable for flow cytometry. Considering that flow cytometry has an important advantage of providing the results on the examination day itself, the results of this study suggest that flow cytometric analysis using our single-step lymphocyte isolation technique can be potentially used to diagnose lymphoma in the gastrointestinal mucosa. • We introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment. • Our technique is feasible for flow cytometric analysis in patients with gastrointestinal lymphoma as well as those with gastrointestinal lesions that are suspected to be lymphoma.

Abstract An abnormal clonal plasma cell proliferation with Russell bodies is rare in chronic inflammatory reactions in adult patients. We describe the first case of light chain restricted Russell body accumulation within germinal centers of lymphoid follicles of the tonsil in a child. This should not be confused with a neoplastic process.

Objective: The previously reported kappa/lambda ratio cut-offs for plasma cell clonality by immunohistochemistry were in different values. This study aimed to identify the cut-offs with the highest accuracy for the diagnosis of multiple myeloma. Methods: Bone marrow specimens consecutively recruited between January 2011 and March 2019. The patients were at least 18 years old with clinical suspicion of multiple myeloma and had bone marrow plasma cell ≥10% by CD138 immunohistochemistry. The index test was immunohistochemical stains for plasma cell kappa/lambda ratio. The reference standard to classify as multiple myeloma required meeting any of the following (1) kappa/lambda ratio ≤1/16 or ≥16, (2) abnormal plasma cell morphology, and (3) monoclonal immunoglobulin. Results: From 147 specimens (70 multiple myelomas and 77 reactive plasmacytosis), our cut-offs kappa/lambda ratio for light chain restriction at ≤1/7 or ≥9 yielded an area under the receiver operating characteristic curve of 1.0000 while ≤1/16 or ≥16 yielded 0.9643 (p-value 0.0212). Conclusion: The cut-offs for kappa/lambda ratio at ≤1/7 or ≥9 for diagnosis of multiple myeloma yielded the highest diagnostic accuracy. The suggested cut-offs could be of potential value in resource-limited laboratories. [ABSTRACT FROM AUTHOR]

Monoclonal gammopathy of renal significance is a recently described entity in which a small B-cell clone not meeting the criteria for the diagnosis of multiple myeloma produces renal disease usually through deposition of a secreted monoclonal immunoglobulin. Here, we describe a case of Type I cryoglobulinemic glomerulonephritis diagnosed on a kidney biopsy and caused by a monoclonal IgM produced by a small bone marrow clone. The patient made a complete renal recovery after chemotherapy to suppress the clone. [ABSTRACT FROM AUTHOR]

Surface light chain expression is a feature of mature B-cell neoplasms. Light chain restriction in precursor B acute lymphoblastic leukemia is infrequently seen. We report a case of a 28-year-old female with non-FAB L3 morphology blasts and immunophenotypic features showing overlap between a precursor and mature B-cell neoplasm.

An abnormal clonal plasma cell proliferation with Russell bodies is rare in chronic inflammatory reactions in adult patients. We describe the first case of light chain restricted Russell body accumulation within germinal centers of lymphoid follicles of the tonsil in a child. This should not be confused with a neoplastic process. [ABSTRACT FROM AUTHOR]

Background: The existence of immunoglobulin light chain restriction (LCR) strongly indicates B cell monoclonality. Although LCR-deficient B cell malignancies are often observed, their details are barely known. Methods: We retrospectively analyzed LCR-negative diffuse large B cell lymphoma (DLBCL) to elucidate their clinical features. Consecutive DLBCL patients (n = 119), whose histological diagnostic specimens were analyzed by flow cytometry (FCM), were divided into 2 groups: LCR-positive and LCR-negative DLBCL. Cases wherein FCM did not capture tumor cells were excluded. Results: There were 91 LCR-positive (76%) and 28 LCR-negative (24%) DLBCL. The 2 groups did not differ with regard to background, including the International Prognostic Index (IPI), each factor of IPI, gender, bulky mass and B-symptoms. FCM analysis showed that CD10-positive cases were less frequent in the LCR-negative DLBCL group than in the LCR-positive DLBCL group. CD5-positive cases were absent in the LCR-negative DLBCL group. Chromosomal analysis showed that the frequency of BCL2, BCL6 and MYC translocations did not differ between the groups. There was no survival difference in the groups. Conclusion: LCR-negative DLBCL accounts for about one fourth of all DLBCL and their prognosis is similar to that of LCR-positive DLBCL. CD10-negative status might characterize LCR-negative DLBCL. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Aims: Light-chain-restricted germinal centres are generally associated with the existence of a neoplastic lymphoproliferative disorder. The aim was to present a series of cases with persistent lymph node enlargement that featured some germinal centres showing light chain immunoglobulin restriction. Methods and results: A series of six reactive lymphadenitis and two Castleman’s disease cases was analysed by immunohistochemistry, IgH-polymerase chain reaction (PCR) and microdissected PCR. In all cases some germinal centres contained a population of plasma cells and plasmacytoid germinal centre cells showing light chain immunoglobulin restriction. In three cases the monotypic cells also showed distinct Bcl-2 expression. Two of the cases showed a predominant IgH rearrangement on a florid polyclonal background and one had an IgH monoclonal rearrangement, as revealed by PCR. Microdissected germinal centre PCR revealed a dominant repeated band in one of three cases and in another case a non-repeated clonal peak was observed. One of the patients developed a follicular lymphoma, which became evident from a subsequent biopsy. Conclusions: These findings may be a manifestation of an underlying disorder in the regulation of the immune response, or an exaggeration of the germinal centre oligoclonal nature. This should be taken into account in the differential diagnosis of follicular hyperplasia. [ABSTRACT FROM AUTHOR]

Light-chain restricted hematogones (LCR HGs) detected by flow cytometry (FC) may, occur in bone marrow mimicking involvement by a B-cell lymphoma. This phenomenon can present a diagnostic pitfall and negatively impact patient management, and may occur in other organs, including lymph nodes, For this reason, it is recommended to utilize, in case of LCR in lymph node, one additional morphological, phenotypical or molecular criteria for the diagnosis of lymphoma on cytological samples., Competing Interests: All authors do not have any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work, (© 2022 The Authors.)

Monoclonal gammopathy (MG) causes various nephropathies, which may suffice for cytoreductive therapy even in the absence of diagnostic criteria for multiple myeloma or B-cell non-Hodgkin lymphoma. The aim of this study was to better understand the significance of light chain (LC) restriction or crystals (LC-R/C) in proximal tubules in the spectrum of LC-induced nephropathies. A consecutive cohort of 320 renal specimens with a history of B-cell dyscrasia was characterized. Special attention was paid to immunohistochemical LC restriction in proximal tubules, tubular crystals or constipation, and ultrastructural findings. Complementary cell culture experiments were performed to assess the role of LC concentrations in generating LC restriction. Light chain restriction or crystals in proximal tubules was found in a quarter of analyzed cases (81/316) and was associated with another LC-induced disease in 70.4% (57/81), especially LC cast-nephropathy (cast-NP) and interstitial myeloma infiltration. LC restriction without significant signs of acute tubular injury was observed in 11.1% (9/81). LC-R/C was not associated with inferior renal function compared to the remainder of cases, when cases with accompanying cast-NP were excluded. Besides crystals, cloudy lysosomes were significantly associated with LC-R/C on an ultrastructural level. In summary, LC-R/C is frequent and strongly associated with cast-NP, possibly indicating that a high load of clonal LC is responsible for this phenomenon, supported by the observation that LC restriction can artificially be generated in cell culture. This and the lack of significant tubular injury in a subgroup imply that in part LC-R/C is a tubular trafficking phenomenon rather than an independent disease process., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Büttner-Herold, Krieglstein, Chuva, Minuth, Pfister, Daniel, Klewer, Büttner, Ferrazzi, Bertz and Amann.)

In this paper, we introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment. For lymphocyte isolation, an endoscopically harvested specimen and 5 mL of normal saline solution were placed in a wire mesh strainer set in a porcelain bowl. To obtain the lymphocyte suspension, the solid specimen was crushed using the rubber portion of a plunger of a 10 mL injection syringe. Flow cytometry was performed using the lymphocyte suspension. For validating our methods, the one-step lymphocyte isolation technique was used to perform flow cytometry on samples from 23 patients with (n = 12) or without (n = 11) gastrointestinal lymphoma. Flow cytometry of light chain expression was performed in all patient samples (feasibility: 100%). Sensitivity was 83.3% (10/12) and specificity was 100% (11/11). In conclusion, lymphocytes isolated from a single endoscopic biopsy specimen using our simplified and quick procedure are suitable for flow cytometry. Considering that flow cytometry has an important advantage of providing the results on the examination day itself, the results of this study suggest that flow cytometric analysis using our single-step lymphocyte isolation technique can be potentially used to diagnose lymphoma in the gastrointestinal mucosa. •We introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment.•Our technique is feasible for flow cytometric analysis in patients with gastrointestinal lymphoma as well as those with gastrointestinal lesions that are suspected to be lymphoma., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s). Published by Elsevier B.V.)

Objective: Flow cytometry has not been widely used in routine clinical practice for the diagnosis of gastrointestinal lymphoma; this is mainly because of the absence of an appropriate protocol. Here, we established a protocol for flow cytometric analysis of a single biopsy specimen from the gastrointestinal mucosa and investigated its sensitivity and specificity., Design: In this prospective study, we enrolled patients with previously diagnosed gastrointestinal lymphoma and patients with gastrointestinal lesions that were suspected to be lymphoma., Results: Overall, 15 patients with gastric extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (N=8), duodenal follicular lymphoma (grade 1; N=5), and benign lymphoid hyperplasia (ileum, N=1, and rectum, N=1) were included in this study. Of these, lymphocytes were isolated from 14 patients (93.3%). There were 200,000-1,500,000 viable cells per patient. Biopsy specimens from 10 out of the 12 patients with lymphoma were positive for light chain restriction; the two patients with benign lymphoid hyperplasia showed negative results., Conclusions: An adequate number of lymphocytes for flow cytometry could be isolated from a single specimen of endoscopic mucosal biopsy from 93.3% of the patients. Overall, the sensitivity of flow cytometric analysis of light chain expression for the diagnosis of B-cell lymphoma was 83.3%, and the specificity was 100%. Although further investigation is required as the sample size of the present study was small, our study suggests a potential option for diagnosing B-cell lymphoma in the gastrointestinal mucosa., (© 2020 by the Association of Clinical Scientists, Inc.)

Background: Daratumumab (DARA) is a humanized Immunoglobulin G(IgG)1-kappa monoclonal antibody against CD38 antigen that is shown to improve outcomes in relapsed/refractory plasma cell myeloma (PCM) patients. Since CD38 is expressed by different hematopoietic elements, DARA has the potential to interfere with flow cytometric assessment of bone marrow specimens., Methods: Flow cytometric analysis of bone marrow samples from 10 PCM on DARA and 5 control samples was performed using two different antibody panels., Results: Bone marrow samples from PCM patients on DARA exhibited a population of CD19+ CD10+ B-lymphoid cells with kappa light chain restriction. Further morphological and immunophenotypic studies suggested that this population represents marrow hematogones. Marrow hematogones from control samples showed normal immunophenotypic profiles., Conclusion: DARA on the surface of hematogones interferes with flow cytometric clonality study leading to artifactual kappa light chain restriction, which can result in false interpretation of a concurrent clonal B-cell proliferation. In the era of rapidly growing list of therapeutic monoclonal antibodies, flow cytometry pathologists should be aware of potential interferences to avoid misdiagnosis. © 2019 International Clinical Cytometry Society., (© 2019 International Clinical Cytometry Society.)