Surface Immunoglobulin Light Chain Research Articles

The kappa/lambda ratio of surface immunoglobulin light chain as a valuable parameter for MRD assessment in CLL with atypical immunophenotype

In recent years, the significance of detecting minimal/measurable residual disease (MRD) in chronic lymphocytic leukemia (CLL) has increased due to the availability of highly effective therapeutic agents. Flow cytometry provides notable cost-effectiveness and immediacy, with an expected sensitivity level of approximately 10−4. The critical aspect of MRD detection via flow cytometry lies in accurately defining the region containing tumor cells. However, a subset of CLL, known as CLL with atypical immunophenotype, exhibits a distinct cell surface marker expression pattern that can make MRD detection challenging, because these markers often resemble those of normal B cells. To enhance the sensitivity of MRD detection in such atypical cases of CLL, we have capitalized on the observation that cell surface immunoglobulin (sIg) light chains tend to be expressed at a higher level in this subtype. For every four two-dimensional plots of cell surface markers, we used a plot to evaluate the expression of sIg kappa/lambda light chains and identified regions where the kappa/lambda ratio of sIg light chains deviated from a designated threshold within the putative CLL cell region. Using this method, we could detect atypical CLL cells at a level of 10−4. We propose this method as an effective MRD assay.

A Unique Case of Large Pelvic Non-Hodgkin Lymphoma

Introduction: Non-Hodgkin lymphoma (NHL) represents a diverse group of malignancies arising from lymphocytes and lymphoid tissues. It encompasses multiple subtypes, including the aggressive diffuse large B-cell lymphoma (DLBCL), which is the most common type of NHL in adults. DLBCL typically presents as a rapidly growing mass in the lymph nodes or extranodal sites. While DLBCL can affect various regions of the body, its occurrence in the pelvic region is infrequent and poses unique diagnostic and therapeutic challenges. Case Description: We present a rare and intriguing case of a 51-year-old female admitted for acute on chronic microcytic anemia, with accompanying symptoms of decreased oral intake due to nausea, and vomiting, significant weight loss, night sweats, and lower quadrant abdominal pain. Additionally, she reported decreased urinary frequency, urgency. CT imaging of the abdomen and pelvis revealed a large soft tissue mass measuring 7.6 x 4.6 x 5.7 cm in the posterior right pelvic region, resulting in severe hydroureteronephrosis, along with bilateral iliac chain adenopathy, retroperitoneal lymph node enlargement, and severe splenomegaly. CT chest revealed several small lung nodules indicating distant metastasis. Additionally, the patient exhibited elevated levels of LDH, CA 199, and CRP, and decreased hemoglobin levels, indicating the presence of systemic disease. A CT-guided biopsy of the right pelvic mass confirmed the diagnosis of non-Hodgkin malignant lymphoma, specifically of the diffuse large B-cell type. Immunohistochemistry and flow cytometry demonstrated CD20 positivity in the proliferating large cells, consistent with DLBCL, and revealed a kappa-restricted B-cell population expressing CD19, CD20, and kappa surface immunoglobulin light chains. The PET scan showed prominent splenomegaly, adenopathy, and retroperitoneal involvement, corroborating the lymphoma diagnosis. The patient was discharged for outpatient follow-up with oncology with a treatment plan of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) administered every 3 weeks, omitting rituximab during the first cycle. Discussion: This case stands out due to the unusual presentation of a large DLBCL in the pelvic region, which is a relatively rare occurrence. The localization of DLBCL in the pelvis poses a diagnostic challenge, as symptoms may overlap with various other conditions. Moreover, the extensive involvement of the retroperitoneal lymph nodes and splenomegaly added complexity to the management of the disease. The rarity of DLBCL in the pelvis highlights the importance of considering lymphoma in the differential diagnosis of patients presenting with non-specific pelvic symptoms and acute anemia. Early recognition of such cases is crucial for timely intervention and optimal treatment planning. Understanding the immunophenotypic characteristics of the tumor is essential for tailoring effective therapeutic strategies. This unique case sheds light on the need for further research and evidence-based guidelines for managing NHL in uncommon anatomical locations, promoting better patient outcomes and quality of life.

Acute Lymphoblastic Leukemia With Surface Light Chain Expression

Acute Lymphoblastic leukemias (ALL) are a heterogeneous group of neoplasms which can either be having precursor B cell immunophenotype or mature B cell immunophenotype. Surface immunoglobulin light chain restriction is usually a feature of mature B cell neoplasms. A precursor B cell lymphoblastic leukemia (pre-B-ALL) with surface immunoglobulin light chain expression is a rare immunophenotype . We report a case of a 4 year old female with L1 type of blast morphology yet showing surface light chain restriction. Recognizing this rare immunophenotype and arriving at a correct diagnosis has therapeutic implications as treatment regimens differ for precursor B ALL as compared to mature B cell neoplasms.

Diagnostic and prognostic values of flow cytometry in diffuse large B-cell lymphoma with bone marrow involvement

Objective: To analyze the diagnostic and prognostic values of flow cytometry (FC) in diffuse large B cell lymphoma (DLBCL) with bone marrow involvement (BMI). Methods: The clinical data of 412 patients with newly diagnosed DLBCL, including 243 males and 169 females, aged 64 (28-92) years old, in the Department of Hematology at Peking University Third Hospital from December 2012 to June 2022 were retrospectively analyzed. All patients underwent bone marrow biopsy (BMB) and bone marrow FC. The patients with BMI by FC were further detected by fluorescence in situ hybridization (FISH) for gene analysis. The positive rates and consistency of BMI detected by BMB and FC were evaluated. According to the results of BMB and FC examinations, all patients were divided into four groups: the BMB+FC+group (115 cases), the BMB-FC+group (50 cases), the BMB+FC-group (8 cases, the results did not include in statistical analysis because of small sample size), and the BMB-FC-group (239 cases). The clinical features, treatment response rates, 5-year survival rates, and immunophenotype characteristics by FC in different groups were analyzed. Results: Among the 412 patients with DLBCL, the positivity rates of BMB and FC for BMI detection were 29.9% (123/412) and 40.0% (165/412), respectively. Good consistency between BMB and FC was found (Kappa=0.841, P=0.001). The numbers of extranodal involvement≥2, splenomegaly, huge mass, higher Ki-67 score, higher international prognostic index (IPI) score, thrombocytopenia, and elevated lactate dehydrogenase level were more prevalent in the BMB+FC+group than those in the BMB-FC+group and the BMB-FC-group (all P<0.05). The treatment response rate in BMB+FC+group was 63.5% (73/115), which was lower than those in BMB-FC+group (88.0%, 44/50, P=0.048) and BMB-FC-group (90.0%, 215/239, P=0.032), respectively. The 5-year overall survival rates in three groups were (53.6±9.7) %, (72.5±8.6) %, and (75.2±7.6) %, respectively, with a statistically significant difference (P=0.037). According to the FISH results of bone marrow, 102 cases were diagnosed as not otherwise specified (NOS), 48 cases were diagnosed as double hit lymphoma (DHL), and 15 cases were diagnosed as triple hit lymphoma (THL). Compared with NOS subtypes, the tumor cells in DHL or THL subtypes had higher proportion of increased side scatter (SSC), higher positive rates of CD10 expression, CD38 strong expression and CD56 expression, and lower proportion of surface immunoglobulin light chain restriction (all P<0.05). Conclusions: FC is well consistent with BMB in diagnosing DLBCL with BMI. Combined with FISH detection, FC can contribute to the auxiliary diagnosis and risk stratification for DHL and THL, and provide reference for the prognostic evaluation in DLBCL with BMI.

The patterns and diagnostic significance of the lack of surface immunoglobulin light chain on mature B cells in clinical samples for lymphoma workup.

Surface immunoglobulin (sIg) light chains are not always detected on mature B cells. This may present as a challenge for clonality determination in clinical flow cytometry. To explore the mechanism and diagnostic significance of sIg negative mature B cells, we retrospectively studied 14 cases of sIg negative reactive B-cell lymphocytosis and 89 cases of sIg negative mature B-cell lymphomas. The expression patterns of sIg and cytoplasmic immunoglobulin (cIg) light chains were studied by flow cytometry using both monoclonal and polyclonal antibodies. These 14 cases of sIg negative reactive B-cell lymphocytosis were proven to be polytypic based on cytoplasmic light chain studies. In 89 cases of sIg negative mature B-cell lymphomas, we described four distinct patterns of abnormal light chain expression including partial or complete loss of sIg or cIg, suggesting different underlying mechanisms. This study represents the first reported series of body or cystic fluids where reactive B cells do not have detectable sIg, arguing strongly against making a diagnosis of B-cell lymphoma based on lack of sIg in mature B cells. Since the lack of sIg does not always predict clonal/neoplastic mature B-cell proliferation, further cIg evaluation should be performed when sIg expression is not detected in mature B cells. The lack of both sIg and cIg in mature B cells may serve as a reliable surrogate clonality/neoplastic marker.

Mantle cell lymphoma with chronic lymphocytic leukemia-like features: a diagnostic mimic and pitfall

Mantle cell lymphoma (MCL) is a mature B-cell neoplasm characterized by t(11;14) (q13;q32) and cyclin D1 overexpression in >95% of cases. Classic MCL cases are composed of a monotonous population of small- to medium-sized lymphocytes with irregular nuclear contours that are positive for cyclin D1 and SOX11and negative for CD23 and CD200. By contrast, occasional MCL cases express CD23 and CD200 but lack SOX11and morphologically and immunophenotypically resemble chronic lymphocytic leukemia (CLL), termed as CLL-like MCL in this study. These neoplasms pose a diagnostic challenge and are easy to be diagnosed as CLL in daily practice. We studied 14 cases of CLL-like MCL to define their clinicopathologic features and compared them with 33 traditional CLL cases. There were 8 men and 6 women with a median age of 62 years (range, 44-80). Compared with CLL, patients with CLL-like MCL have lower levels of peripheral blood and bone marrow involvementand more frequently had mutated IGHV. Immunophenotypically, CLL-like MCL often showed moderate to bright expression of B-cell antigens and surface immunoglobulin light chain, dim and partial expression of CD23 and CD200, infrequent CD43 positivity, and lack of LEF1. The overall survival of patients with CLL-like MCL was similar to that of CLL patients. In conclusion, CD23+, CD200+, and SOX11-negative MCL closely resemble CLL, both clinically and pathologically, including a similar indolent clinical course. They may pose a diagnostic challenge. However, patients with CLL-like MCL also have distinctive immunophenotypic features that are useful to distinguish these neoplasms from CLL.

Clinicopathological analysis of diffuse large B-cell lymphoma lacking surface immunoglobulin light chain restriction on flow cytometry.

Although diffuse large B-cell lymphoma (DLBCL) occasionally lacks surface immunoglobulin light chain restriction (iLCR) on flow cytometry (FCM), little evidence is available for iLCR-negative DLBCL. We retrospectively compared clinicopathological features of iLCR-positive and iLCR-negative DLBCL diagnosed at our institute between April 2007 and March 2018. iLCR-positive was defined as a κ/λ ratio less than 0.5 or greater than 3 in the gated population on dual-color FCM, and iLCR-negative as other values. Of 81 DLBCL cases with available immunophenotyping by FCM, 63 iLCR-positive DLBCL (78%) and 18 iLCR-negative DLBCL (22%) cases were identified. Survival outcomes of patients with iLCR-negative DLBCL were comparable with those of patients with iLCR-positive DLBCL. Pathological analysis revealed no significant difference except for the lower expression of BCL6 in iLCR-negative DLBCL (12.5% vs 65.5%, p < 0.001), although there was a slightly higher frequency of necrosis (47.1% vs 20.7%, p = 0.058) and lower expression of CD10 (11.8% vs 35.0%, p = 0.078) in iLCR-negative DLBCL than in iLCR-positive DLBCL. The underlying mechanism remains unclear; however, low expression of germinal center markers and tumor necrosis may be associated with the loss of iLCR in DLBCL.

Mature B cell acute lymphoblastic leukaemia with KMT2A-MLLT3 transcripts in children: three case reports and literature reviews

BackgroundMature B cell acute lymphoblastic leukaemia (BAL) is characterised by French–American–British (FAB)-L3 morphology and the presence of surface immunoglobulin (sIgM) light chain restriction. BAL is also considered as the leukaemic phase of Burkitt lymphoma (BL), in which t (8; 14) (q24; q32) or its variants are related to the myelocytomatosis oncogene (MYC) rearrangement (MYCr) is usually present. However, BAL with lysine methyltransferase 2A (KMT2A, previously called Mixed lineage leukaemia, MLL) gene rearrangement (KMT2Ar, previously called MLLr) is rare.ResultsThree BAL patients with KMT2Ar were enrolled between January 2017 and November 2019, accounting for 1.37% of the B-ALL population in our hospital. We also reviewed 24 previously reported cases of BAL and KMT2Ar and analysed the features, treatment, and prognosis. Total 13 males and 14 females were enrolled in our research, and the average age at diagnosis was 19.5 ± 4.95 months old. In these 27 patients, renal, central nervous system (CNS) and skin involvement were existent in 6, 4 and 3 patients, respectively; 26 patients (26/27) showed non-ALL-L3 morphology, while one patient is ALL-L3; overexpression of CD19 was detected in most cases, negative or suspicious expression of CD20 was found in 64% of patients. KMT2Ar was reported, but MYCr was not observed. 25 patients (25/27) achieved complete remission after chemotherapy or Stem cell transplantation. The patients were sensitive to chemotherapy, prospective event-free survival (pEFS) of BAL patients with KMT2Ar who received allogeneic haematopoietic stem cell transplantation (allo-HSCT) was higher than that in patients who received chemotherapy alone (83.33% vs 41.91%).ConclusionBAL patients with KMT2Ar had unique manifestations, including younger age at diagnosis and overexpression of CD19; expression of CD20 was rare, and MYCr was undetectable. The pEFS was higher in patients undergoing allo-HSCT than in patients undergoing chemotherapy alone.

Flow cytometry in the diagnosis of mature B-cell lymphoproliferative disorders.

B-lineage lymphoproliferative disorders (LPD) are rather frequent diseases, associated with specific clinical or biological features but also sometimes of fortuitous discovery. Multiparameter flow cytometry plays a major role for a rapid diagnostic indication, on peripheral blood or bone marrow samples in most instances, guiding complementary analyses and allowing for the proper therapeutic management of patients. After describing the important pre-analytical precautions required for an adequate assessment, the immunophenotypic features of small-cell and large-cell lymphomas are described in this review. The ubiquitous expression of CD19 is a first mandatory gating step. A possible clonal proliferation is then suspected by the demonstration of surface immunoglobulin light chain restriction. The aberrant presence of CD5 allows to segregate chronic lymphocytic leukemia and mantle cell lymphoma in most cases. Other LPD exhibit specific immunophenotypic features. A table of useful markers and a decision tree are provided. Of note, immunophenotypic data should as much as possible be interpreted in an integrated manner, involving the patient's clinical and other biological features, and be completed by further chromosomal and/or molecular investigations.

The Grey Zone: Characterization of Aggressive High-Grade B-Cell Malignancy with TdT Expression and IGH/BCL2 and MYC Rearrangement

Accurately distinguishing between mature and immature B-cell neoplasms is crucial for determining therapy. However, overlapping morphologic, cytogenetic and immunophenotypic characteristics can have diagnostic and therapeutic implications. Morphologically, high grade B-cell lymphoma with double/triple hit (HGBL) may have a "starry sky" or blastoid appearance that can resemble B-lymphoblastic leukemia (B-LBL), Burkitt's Lymphoma (BL) or diffuse large B cell lymphomas (DLBCL), but differ from immature B-cell neoplasms with expression of CD20, CD10, MUM1, and surface immunoglobulin light chains (sIG). Conversely, B-LBL and B-ALL lymphoblasts have dim or lack expression of CD20 and sIG and express markers of immaturity such as CD34 and terminal deoxynucleotidyl transferase (TdT). In this study, we present our institutional experience of 8 patients with a "grey zone" leukemia/lymphoma: 4 patients with aggressive TdT-positive HGBL and 4 patients with B-LBL or B-ALL with a "double-hit" karyotype. We hypothesize these cases may represent a separate entity between HGBL and B-LBL/B-ALL with activating Myc rearrangements. Our cohort was compiled by reviewing cases encountered in our clinical practice from July 2015 to July 2019 that could be identified as follows: (1) de novo HGBL with MYC, BCL2, and/or BCL6 rearrangements or amplifications with concurrent aberrant TdT expression at diagnosis or in subsequent biopsies and (2) de novo B-LBL or B-ALL with a "double‐hit" karyotype. Clinical and diagnostic data were obtained by review of the medical records. The Moffitt Cancer Center Institutional Review Board approved this retrospective study. Of patients with HGBL with aberrant TdT expression, 3 were HGBL with triple hit and 1 with a Bcl6 rearrangement and Bcl2 and Myc amplifications. These patients presented with aggressive features including elevated LDH at diagnosis, high IPI score, and Ki-67 &gt;/= 80%, however without bone marrow or CNS involvement. They express a typical GCB immunophenotype, positive for CD10, CD20, and MUM1 and negative for CD34 (Table 1). These patients were treated with DA-EPOCH-R (3) and R-CHOP (1), of which 1 achieved a partial response and 3 developed progressive disease (Table 2). Three patients went on to consolidative therapy with CD19-directed CAR-T (66%) or autologous transplant (33%). The median overall survival (mOS) was 12.1 months. In the second group, 2 were considered B-ALL based on immature morphology and lack of mature B-cell markers (CD20 negative or variable and MUM1 negative), although they did not express TdT. They both showed IGH-Bcl2 and Myc rearrangements. They were treated with DA-EPOCH-R, of which 1 experienced progressive disease and 1 was unable to complete therapy. The other 2 patients were diagnosed with de novo B-LBL that was CD10 and TdT positive. Of these, 1 showed MUM1 positivity and genomic testing revealed IGH-Bcl2 and Myc rearrangements accompanied by a TP53 mutation. The other showed IGH-Bcl2 rearrangement and Myc activating mutation. One was treated with HyperCVAD with an interval CR and the other with modified DFCI died 5.1 months after diagnosis. Prognosis in this second subset was poor with a mOS of 5.3 months. Within the entire cohort, the majority (75%) were treated as DLBCL with R-CHOP-based therapy, while the remaining (25%) were treated with HyperCVAD. 25% experienced a PR or interval CR, while the remainder experienced progressive disease (PD). Overall, we observed a median PFS of 6.6 months and mOS 5.6 months with 0% undergoing allogeneic transplant in first remission, 1 (12.5%) undergoing autogeneic transplant in first remission and 2 (25%) undergoing CD19-directed CAR-T following salvage therapy. HGBL that has acquired TdT expression and B-LBL/B-ALL associated with IGH/BCL2 translocation and activating MYC rearrangements or mutations are uncommon, but represent a biologically unique group with a poor clinical outcome, likely due to accumulated somatic hypermutations. The high percentage of MUM1 expression in these cases suggests a role of dysregulated MUM1 in cooperation with Myc dysregulation. The recognition of this group may be under-appreciated due to the lack of awareness. Inclusion of evaluation of TDT in "mature" HGBL and identification of genetic alterations including BCL-2, BCL-6 and Myc in "immature" B-LBL/B-ALL will be helpful. Consolidation upon first remission with transplant or CAR-T may be of benefit. Disclosures Chavez: Genentech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees. Bello:Celgene: Speakers Bureau. Bunting:Transenterix: Equity Ownership; Tilray: Equity Ownership; Crispre: Equity Ownership; Celgene: Equity Ownership. Shah:Kite/Gilead: Honoraria; Adaptive Biotechnologies: Honoraria; AstraZeneca: Honoraria; Novartis: Honoraria; Spectrum/Astrotech: Honoraria; Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Pharmacyclics: Honoraria; Celgene/Juno: Honoraria.

Bright CD38 Expression by Flow Cytometric Analysis Is a Biomarker for Double/Triple Hit Lymphomas with a Moderate Sensitivity and High Specificity.

High-grade B-cell lymphomas (HGBCL) with MYC and BCL2 or/and BCL6 rearrangements (R), so-called double/triple-hit lymphomas (DH/THL), are uncommon, clinically aggressive lymphomas that require a prompt diagnosis. We aim to identify flow cytometric immunophenotypic (IP) features of DH/THL that may aid in triaging these cases followed by a timely confirmatory cytogenetic study. We compared the IP features of 43 cases of DH/THL to those of 55 cases of single-hit lymphoma (SHL) and 59 cases of diffuse large B-cell lymphoma (DLBCL) without MYC-R (MYCneg DLBCL). We analyzed the expression patterns of CD10, CD19, CD20, CD38, and surface immunoglobulin light chain in lymphoma cells. Bright CD38 expression (CD38bright ) analyzed either qualitatively or semi-quantitatively was more common in DH/THL (56%) than in MYCneg DLBCL (17%) but less common compared to SHL (82%), indicating that CD38bright can serve as a biomarker for DH/THL. Additionally, CD38bright may be a better indicator for predicting DH/THL-BCL2 than DHL-BCL6, and very bright CD38 expression was exclusive to MYC rearranged lymphomas. The expression patterns of other markers were similar among these lymphoma groups. CD38bright is a biomarker associated with DH/THL with a moderate sensitivity (~50%) and high specificity (~90%). While this marker cannot be used as a screening tool, awareness of this correlation may aid in expediting the diagnosis and prioritizing FISH testing in resource limited settings or situations when samples are limited. Future studies to combine immunohistochemical markers are needed to further enhance the predictive power of CD38bright in diagnosing DH/THL. © 2019 International Clinical Cytometry Society.

The Diagnostic Value of Kappa/Lambda Ratios Determined By Flow Cytometric Analysis of Peripheral Blood and Bone Marrow Specimens in B-Cell Chronic Proliferative Disease

Background. Previous studies have suggested that analysis of the distribution of surface immunoglobulin light chain kappa and lambda by flow cytometry (FC) provides evidence for monoclonality of B cell tumors in patients with persistent lymphocytosis. The objective is this study is to investigate the efficiency of FC in determination of monoclonality in patients with persistent lymphocytosis through the analysis of kappa and lambda light chain of immunoglobulin expression (kappa/lambda tests). Methods: Samples of peripheral blood from 43 patients with B-CLD were analyzed. They were analyzed by FC with monoclonal antibody panel as: CD3, CD4, CD5, CD8, CD10, CD19, CD22, CD20; CD103; FMC7; CD23, CD25, CD38, CD45, CD16/CD56, HLADR, anti- heavy chain of immunoglobulin (IgH), anti-heavy chain m and d of immunoglobulin (IgM/IgD) and anti-light chains (kappa and lambda) of immunoglobulin. In addition, information about sex, age and clinical and hematological data from the patients were also evaluated. Results. A relation between kappa / lambda higher than 10:1 was found in all samples, suggesting a monoclonal B cells proliferation with 86% of the samples displayed kappa light chain of immunoglobulin expression and 14% displayed lambda light chain of immunoglobulin expression. The immunophenotyping data associated with the hematological and clinical ones, confirmed 35 cases of B-cell chronic lymphocytic leukemia, 3 cases of B-cell prolymphocytic leukemia, 3 of hairy cell leukemia, one case of Waldenstrong macroglobulinemia and mantle cell lymphoma. Conclusions. The results showed that the kappa and lambda light chain of immunoglobulin expression analysis by FC is a simple and effective methodology in the malignant B- cell proliferation. DisclosuresNo relevant conflicts of interest to declare.

Acute B-Lymphoblastic Leukemia With Surface Immunoglobulin Light Chain Restriction: Case Report

B-lymphoblastic leukemia (B-ALL) is a neoplasm of B lymphoblasts that are typically negative for surface immunoglobulin light chain with flow cytometry immunophenotype analysis. Few cases have been previously reported of B-ALL with surface immunoglobulin light chain restriction. Previous studies suggest that surface immunoglobulin light chain restriction in precursor B lymphoblasts is not confined to any particular stage of B-lymphoblast differentiation. This study reports a 26-year-old male having B-ALL with surface immunoglobulin light chain restriction. Immunophenotypic patterns were investigated by multiparametric flow cytometry. BCR-ABL1 transcripts were investigated using quantitative PCR, and cytogenetic and FISH analyses were performed to identify chromosomal alterations. At the time of the primary diagnosis, the leukemic cells in this patient had typical morphologic features of B-ALL; expressed CD10, CD19, CD15, CD38, HLA-DR, and CD34; and displayed surface immunoglobulin light chain restriction. The leukemic cells did not express CD20, CD2, CD3, CD4, CD8, CD5, CD7, CD56, TdT, and cMPO. Trisomy 11q and deletion of 21q were detected in this case, which are cytogenetic abnormalities often reported in B-ALL. These results evidence that a precursor B leukemia cannot be ruled out solely by the presence of surface immunoglobulin light chain restriction on leukemic cells by using flow cytometry immunophenotype analysis. The significance of this finding in the clinical course of B-ALL requires further investigation.

B-cell chronic lymphoproliferative disorders: a clinical analysis of 40 cases

Objective To investigate the clinical features, treatment and prognosis of the patients with B-cell chronic lymphoproliferative disorders (B-CLPD). Methods The data of 40 patients with B-CLPD in the Third People's Hospital of Kunshan from September 2010 to June 2017 were retrospectively analyzed, including clinical features, laboratory inspections, immunophenotyping, genetics and molecules results, therapeutic regimens, evaluation of curative effect and disease outcome. Results There were 29 male and 11 female patients in 40 B-CLPD patients, with a median age of 71.5 years old (47-88 years old). The percentage of chronic lymphocytic leukemia (CLL) was 57.5% (23/40), monoclonal B lymphocytosis was 10.0% (4/40), Waldenstrom macroglobulinemia was 15.0% (6/40), marginal/splenic marginal zone lymphoma was 12.5% (5/40), and mantle cell lymphoma was 5.0% (2/40). The immunophenotyping of the whole patients had the expressions of CD19, and surface immunoglobulin light chain in cytomembrane of 37 patients had a restrictive expression. All CLL patients presented the expressions of CD5 and CD23, while the other types of B-CLPD expressed various level of CD20, CD22, CD10, CD5, FCM-7. Twenty-six patients received chemotherapies including purine analogue, anthracyclines, alkylating agents and hormone. The overall response rate (complete remission plus partial remission) was 69.2% (18/26). The complete remission rate was 15.4% (4/26), which only occurred in the cohort of CLL patients who received the regimen containing fludarabine. The median follow up time of 26 patients who received medical treatment was 42.8 months (0.5-82.0 months), not reaching the median survival time. Conclusions The clinical features of B-CLPD are various, which requires comprehensive analysis of clinical data, including medical history, laboratory findings, imageological examination, cell morphology, immunophenotyping, genetics as well as molecular biology. The choice of the treatment should take the individualized situation into consideration. Key words: B-cell chronic lymphoproliferative disease; Clinical features; Diagnosis; Treatment

Issue Highlights-May 2018 (94B3).

Issue Highlights-May 2018 (94B3).

Hematogones With Lambda Light Chain Restriction in a 4-Year-Old Boy With Burkitt Lymphoma: A Potential Diagnostic Pitfall.

Hematogones are immature normal B cell precursors with a characteristic immunophenotype profile on flow cytometry that typically do not express surface immunoglobulin light chains. In this report, we describe a case in which the hematogones exhibit light chain restriction. Our patient was a 4-year-old boy with a complicated medical history involving treatment for a presumed bilateral Wilms tumor of the kidney that on later resection was diagnosed as Burkitt lymphoma. Flow cytometry analysis of his bone marrow revealed a small distinct population of cells expressing dim cluster of differentiation (CD)10, CD19, CD22, CD38, dim CD58, human leukocyte antigen–D related (HLA-DR), and dim CD45, which are characteristic of hematogones. These cells, however, demonstrated dim surface immunoglobulin lambda light-chain restriction. Molecular study results for immunoglobulin heavy and kappa light-chain gene rearrangements were negative. We present this case to raise awareness of the potential pitfalls of working up bone marrow for involvement by B cell lymphoproliferative disorder.

Diffuse Large B-Cell Lymphoma Lacking Surface B-Cell Receptor Expression Are Germinal Center B-Cell (GCB)-Type and Lack Evidence of Known Downstream Activating Mutations

Background: Diffuse large B-cell lymphoma (DLBCL) typically express monotypic surface immunoglobulin (sIg) light chain as part of the B-cell receptor (BCR) complex. Occasional cases are, however, sIg-negative and the clinical significance of this remains unclear. Distinct subtypes of DLBCL, including germinal center B-cell-like (GCB) and activated B-cell (ABC) type, exhibit differential dependence upon BCR-mediated survival signals. The role of activating mutations downstream of the BCR signaling complex (i.e. CD79A/B or CARD11), or in parallel costimulatory pathways (i.e. MYD88 mutations), are now well recognized in promoting such survival mechanisms. Surprisingly, however, less is known about the importance of sIg expression, or lack thereof, on various subsets of DLBCL or other aggressive large B cell lymphomas.Design: We sought to further characterize the clinicopathologic and genetic features of primary human surface Ig-negative DLBCL-not otherwise specified (NOS). All cases of large B-cell lymphoma that had flow cytometry performed at the University of Rochester from 2010-2013 were screened for evidence of a surface Ig-negative B-cell population. Additional available immunophenotypic data and/or clinicopathologic features were recorded. PCR heteroduplex analysis and sequencing of fresh frozen tumor samples was performed to identify putative compensatory activating mutations in MYD88 and CD79A /B, respectively. In addition, using multiplexed PCR and sequencing analysis we attempted to identify the presence or absence of functional immunoglobulin heavy chain (IGH)gene rearrangements.Results: Among 209 diagnostic specimens analyzed, 13 cases (6.2%) were found to contain a discrete population of CD19/CD20-positive B-cells lacking sIg light chain expression. These included 8 DLBCL-NOS, nearly all of which were GCB-type, including 6 out of 7 cases, or 83%, which were CD10-positive. This proportion is significantly greater than the 42% of all DLBCL-NOS that express CD10 (based on data from a large publicly available on-line database; p < 0.025, based on binomial probability). Furthermore, of the other high grade sIg-negative B cell lymphomas identified, 4 out of 5 were also CD10-positive. These included 2 cases of B-cell lymphoma, unclassifiable (BCL-U), intermediate between DLBCL and Burkitt lymphoma, and 2 cases of transformed follicular lymphoma (FL) - therefore also histologically and immunophenotypically consistent with derivation from a germinal center B-cell. The only exception was a non-GCB primary CNS lymphoma. Among 5 cases of sIg- DLBCL available for analysis, all were negative for the MYD88 L265P activating mutation, while only a single case contained an activating mutation in CD79A/B (CD79B Y196 ITAM mutation). In the same set, only 2 (of 5) cases produced amplicons by IGH PCR, and sequencing revealed only one of these had an intact reading frame.Conclusion: DLBCL-NOS lacking definitive sIg light chain expression are infrequent (less than 10%), but these tumors are predominantly GCB subtype. This observation lends support to the model that these tumors rely less on BCR-mediated survival signals, which may have implications for choosing targeted therapy. The mechanism by which these lymphoma survive despite the apparent lack of functional BCR is unknown, but compensatory activating mutations known to be frequent among ABC-type DLBCL appear to be lacking. DisclosuresNo relevant conflicts of interest to declare.

Inconclusive flow cytometric surface light chain results; can cytoplasmic light chains, Bcl-2 expression and PCR clonality analysis improve accuracy of cytological diagnoses in B-cell lymphomas?

BackgroundFlow cytometric immunophenotyping (FCI), is widely used in cytology for distinguishing between B-cell lymphoma (BCL) and reactive lymphocytic proliferations (RLP), mainly by identifying monotypic B-cell populations. Since this cannot always be determined by ratios of surface immunoglobulin light chains (sIg LCs) we wanted to assess if cytoplasmic immunoglobulin (cIg) LCs, Bcl-2 and polymerase chain reaction (PCR) based clonality analysis can improve accuracy of cytological diagnoses of BCL.MethodsOur study included 98 fine needle aspiration biopsies from lymph nodes suspicious for BCL with inconclusive sIg LCs. In all cases PCR clonality analysis was performed in order to determine immunoglobulin heavy chain (IGH) gene and T-cell receptor (TRC) gene rearrangement. In selected cases expression of Bcl-2 and cIg LC were determined by FC.ResultsThirty patients had lymphoma and 68 had reactive lymphocytic proliferations. Three patterns of sIg LCs staining were found: negative, dual positive and difficult to interpret. Percentage of lymphomas was highest in the dual positive group (75 %). Morphology coupled with cIg LCs determination and/or Bcl-2 expression was able to give a correct diagnosis in 83 % of cases. Molecular tests would have been misleading in 15 % of cases because 7/30 BCL were polyclonal and 8/68 RLP were monoclonal.ConclusionsDetermination of cIg LCs, Bcl-2 expression and PCR clonality analysis of B cells improved accuracy of cytological diagnoses in BCL with inconclusive sIg LC. However, clonality determined by PCR was misleading in some cases.

Inability of Monoclonal Anti‐light Chain Antibody to Detect Clonal B‐Cells in a Patient with Follicular Lymphoma by Multicolor Flow Cytometry

Our recent publication "Inability of a monoclonal anti-light chain antibody to detect clonal plasma cells in a patient with multiple myeloma by multicolor flow cytometry," underlined the importance of choice of antibodies to detect cytoplasmic light chains. Our present study extends this finding for detection of surface immunoglobulin (SIg) light chains on clonal B-cells. Multicolor flow cytometry was used for analyzing bone marrow (BM) from a patient with a CD10-positive follicular lymphoma for infiltrating clonal B-cells. In the BM aspirate, B cells could be identified expressing CD19, CD10, and high levels of CD20. No SIg light chain expression was found on this population of B cells employing monoclonal antibodies. Re-analysis using polyclonal antibodies against SIg light chains, revealed presence of lambda light chains on the CD10positive B-cells. These data illustrate when antibodies against SIg light chains are employed for B-cell clonality assessment, polyclonal antibodies are preferred over monoclonal antibodies.

Acute Lymphoblastic Leukemia with Mature B-Cell Phenotype and t(9;11;11)(p22;q23;p11.2): A Case Study and Literature Review

Acute Lymphoblastic Leukemia with Mature B-Cell Phenotype and t(9;11;11)(p22;q23;p11.2): A Case Study and Literature Review