Lymphoplasmacytic Cells Research Articles

An Anaplastic Lymphoma Kinase (ALK) Immunohistochemical Pitfall: ALK-positive Histiocytosis versus Angiomatoid Fibrous Histiocytoma

Abstract Introduction/Objective The 5th Edition WHO classification expanded the histiocytic/dendritic cell neoplasms to include ALK-positive histiocytosis, which can present as multisystem or single-site disease, affecting various age groups. These tumors lack high-grade cytologic features but express ALK by immunohistochemistry, typically indicating ALK locus rearrangements. In this case study, a cutaneous mass initially suspected as ALK-positive histiocytosis was found to be angiomatoid fibrous histiocytoma (AFH) with ALK expression, highlighting the potential diagnostic pitfall due to overlapping histomorphology and ALK expression. Methods/Case Report A previously healthy twelve-year-old boy sought evaluation for a growing and ulcerating mass on his left arm, which developed gradually over a year post-injury. Laboratory tests showed elevated inflammatory markers and mild anemia. A biopsy of the ulcer revealed Staphylococcus aureus infection. Initial histological examination revealed mixed inflammatory infiltrates with focal necrosis, prominent histiocytes, and giant cells. Despite favoring an infectious cause, immunostains were performed. AE1/AE3, ERG, CD34, CD30, S100, SOX10, SMA, and MyoD1 were negative, while INI1 was retained. However, ALK was strongly positive in some histiocytoid cells, suggesting ALK-positive histiocytosis. Surgical resection was subsequently performed to manage the abscess and characterize the lesion. Histologic examination revealed a solid nodule containing spindled and epithelioid cells with a bland histiocytoid appearance, arranged in a compact syncytial growth pattern within the dermis and subcutis. Surrounding the tumor, there was a distinct cuffing of fibrosis with organized lymphoplasmacytic cells. Break apart fluorescence in situ hybridization studies showed rearrangement of EWSR1 but not ALK. The diagnosis of angiomatoid fibrous histiocytoma was rendered. Results (if a Case Study enter NA) NA Conclusion This case highlights the importance of understanding immunohistochemical features, especially those that are unusual and unexpected in rare diseases. With the growing use of minimally invasive sampling techniques, this case study underscores the significance of integrating molecular diagnostics with clinical, histological, and immunophenotypic evaluations to achieve an accurate diagnosis in surgical pathology.

An Unusual Case of Lymphoplasmacytic Variant of Multiple Myeloma

Abstract Introduction/Objective Multiple myeloma is characterized by unregulated growth of monoclonal plasma cells with overt production of nonfunctional intact immunoglobulins or immunoglobulin chains. Immunohistochemically, the plasma cells are positive for CD138 and CD38, and are rarely positive for CD20 or cyclin D1. CD20 positivity and plasmacytoid morphology in our case pointed towards a lymphoplasmacytic variant of multiple myeloma. The translocation t(11;14) has been detected in this variant, which can explain the positive cyclin D1 immunostaining. The differential diagnosis of this myeloma variant includes lymphoplasmacytic lymphoma. Methods/Case Report We present a case of a 75-year-old female with no significant past medical history who suffered a fall and hesitated to get evaluated until her pain persisted. Initial ER evaluation revealed she had a compression fracture of the T10 and T11 vertebrae with no other abnormality identified. Subsequently, she underwent kyphoplasty, and bone biopsies were performed. The biopsies showed prominent monotonous lymphocytes and some plasmacytoid cell proliferation. Immunostains showed the tumor cells were positive for CD20, Pax-5, Bcl-2, cyclin D1, CD138, and kappa light chain, weakly positive for CD23; and negative for CD5, CD3, CD10, Sox11, and lambda light chain. Based on the morphology and immunoprofile, current findings were considered suggestive of a low-grade B cell lymphoplasmacytic proliferation with cyclin D1 expression. The differential diagnosis includes a lymphoplasmacytic lymphoma or lymphoplasmacytic variant of multiple myeloma. This case was forwarded to a higher-level care facility for consultation and the diagnosis of plasmacytoma, kappa light chain restricted, was rendered. Results (if a Case Study enter NA) NA Conclusion Misdiagnosis of lymphoma can be made in lesions showing classic plasma cells, numerous lymphoplasmacytic cells, and cyclin-D1 positivity on immunohistochemistry if additional testing is not performed. We recommended further testing, including but not limited to bone marrow biopsy, molecular testing, FISH, and genetic testing for a definitive diagnosis.

Waldenstrom's Macroglobulinemia: A Case Report

Waldenström's macroglobulinemia (WM) is a rare, slow-growing hematologic malignancy marked by elevated levels of monoclonal immunoglobulin M (IgM) and bone marrow infiltration by lymphoplasmacytic cells. This case details a 72-year-old man who, during a pre-anesthetic consultation for lumbar spinal stenosis surgery, presented with neurological symptoms, fatigue, and headaches. Examination revealed pallor, and laboratory tests indicated anemia and an elevated erythrocyte sedimentation rate. Serum protein electrophoresis identified a monoclonal IgM spike, and bone marrow aspiration showed significant infiltration by small lymphoid cells, lymphoplasmacytoid cells, and plasma cells. WM was confirmed, and the patient was treated with dexamethasone, rituximab, and cyclophosphamide, with positive follow-up progress. This case underscores the importance of considering WM in the differential diagnosis for patients with unexplained anemia and elevated IgM levels, highlighting the need for timely diagnosis and treatment to manage potential complications.

Histologic findings of gastrointestinal biopsies and clinical outcome in dogs undergoing cholecystectomy for gallbladder mucoceles: 71 cases (2014-2021).

To determine the presence and categorise the severity of enteritis in dogs with gallbladder mucoceles, and evaluate for any associations with enteritis. This study also aimed to report clinical outcome following cholecystectomy and evaluate for associations with survival. Medical records were retrospectively reviewed (2014 to 2021) for dogs undergoing cholecystectomy and duodenal biopsy procedures for gallbladder mucocele. Signalment, bloodwork, abdominal ultrasound findings, surgical details, histology results and outcomes were reported. Surgeries were considered elective or emergent based on each dog's clinical presentation. Enteritis was categorised based on cell type and severity. Inflammation and clinical outcome were statistically evaluated. Seventy-one dogs met the study criteria. Enteritis was present in 85.9% (61/71) of cases with the majority being lymphoplasmacytic (53.5%). Twelve dogs (16.9%) underwent gastrointestinal biopsies from multiple sites, which revealed the same enteritis type at each location. A total of 87.3% (n = 62) dogs survived, including 90.4% elective and 86% emergent cases. No significant differences in enteritis severity or patient survival were found between elective and emergent cases. Septic peritonitis was diagnosed in two dogs (2.82%). Mortality was significantly associated with leukocytosis, with nonsurviving dogs having a mean WBC count of 27.6 G/L (95% confidence interval: 10.6 to 21.5). Enteritis is present in a majority of dogs with gallbladder mucocele, especially mild to moderate with lymphoplasmacytic cell type. Obtaining a duodenal biopsy had minimal impact on patient outcome. Compared to previous studies, improved survival in emergent cases was noted. Further studies with long-term follow-up are needed to determine if enteropathy-related signs persist after cholecystectomy.

A Case of Lymphoplasmacytic Cell Lymphoma Characterized by Marked Nuclear Fission and Brain Gyrus Nuclei of Lymphocytes

A 67-year-old male was admitted to the hospital due to fatigue and thrombocytopenia. Peripheral blood cells analysis showed the white blood cells count of 2.99 × 109 /L, red blood cell (RBC) count of 2.08 × 1012/L, platelet count of 15 × 109 /L. β2- microglobulin of serum was 5.50 mg/L. Whole-body positron emission tomography-computed tomography suggested altered reactivity in the lymph nodes of the bilateral neck. Morphological examination of bone marrow (BM) indicated the presence of abnormal smaller lymphocytes, accounting for 12.5% of the total nucleated cells. Strikingly, nuclear fission or brain gyrus nuclei were prominently observed in all abnormal lymphocytes (Figure 1, original magnification 1000×; Wright–Giemsa stain). The proportion of plasma cells was 0.5%, and no morphological abnormalities were observed. Additionally, some RBCs were exhibited a rouleaux arrangement. Flow cytometry analysis of BM identified 16.12% of κ-restricted B lymphocytes expressing CD5- , CD10- , CD19+ , CD20+ . A minimal proportion of 0.03% plasma cells with κ/λ ratio of 1.07. Consistent results were confirmed by immunohistochemistry in the BM biopsy. Immunofixation electrophoresis revealed abnormal monoclonal bands in the IgM and κ lanes. Furthermore, mutations of MYD88 (L265P), CXCR4 (T318fs), and TP53 (R306X) were identified through next-generation sequencing analysis. A diagnosis of lymphoplasmic cell lymphoma/waldenström macroglobulinemia (LPL/WM) was established.

Current Approaches in the Management of Monoclonal Gammopathies: an approach to Waldenström Macroglobulinemia

Monoclonal gammopathies encompass a spectrum of disorders characterized by the abnormal proliferation of plasma cells, leading to the production of monoclonal immunoglobulins. Waldenström macroglobulinemia (WM) is a rare, indolent lymphoproliferative disorder characterized by the presence of an IgM monoclonal gammopathy, bone marrow infiltration by lymphoplasmacytic cells, and clinical features such as hyperviscosity, lymphadenopathy, and hepatosplenomegaly. Recent advances in understanding the pathogenesis of WM have led to the development of novel therapeutic strategies, including targeted therapies and immunomodulatory agents, which have significantly improved outcomes for patients. This article provides an overview of the current understanding of WM pathophysiology, clinical presentation, diagnostic approach, and recent advancements in its management.

Single-cell analysis of MYD88L265P and MYD88WT Waldenström macroglobulinemia patients.

Waldenström macroglobulinemia (WM) is characterized by the expansion of clonal lymphoplasmacytic cells; the MYD88L265P somatic mutation is found in >90% of patients, but malignant B cells may still display intra-clonal heterogeneity. To assess clonal heterogeneity in WM, we generated and performed single-cell RNA sequencing of CD19+ sorted cells from five patients with MYD88 L265P and two patients with MYD88 WT genotype as well as two healthy donors. We identified distinct transcriptional patterns in the clonal subpopulations not only between the two genetically distinct WM subgroups but also among MYD88 L265P patients, which affected the B cell composition in the different subgroups. Comparison of clonal and normal/polyclonal B cells within each patient sample enabled the identification of patient-specific transcriptional changes. We identified gene signatures active in a subset of MYD88L265P patients, while other signatureswere active in MYD88 WT patients. Finally, gene expression analysis showed common transcriptional features between patients compared to the healthy control but also differentially expressed genes between MYD88 L265P and MYD88 WT patients involved in distinct pathways, including NFκΒ, BCL2, and BTK. Overall, our data highlight the intra-tumor clonal heterogeneity in WM with potential prognostic and therapeutic implications.

Sclerosing Angiomatoid Nodular Transformation of The Spleen: A report of a rare entity

Abstract Introduction/Objective Sclerosing angiomatoid nodular transformation (SANT) is a benign vascular lesion of spleen with uncertain etiology. It predominately affects women between 30 to 60 years of age. Clinically, it is asymptomatic or can cause abdominal pain, but usually discovered incidentally on imaging, which can identify a mass but may not provide a definitive diagnosis. In uncertain vascular lesions, there is always a risk of spontaneous rupture of large vessels and potential for spreading malignancy. Hence, the final diagnosis is rendered on microscopy after splenectomy Methods/Case Report A middle age female came to clinic complaining of abdominal pain. Radiology showed solid splenic mass and the patient underwent splenectomy. Gross examination showed a 3 cm white firm mass with focal hemorrhage. Microscopy revealed multiple nodules of variable sizes surrounded by fibrosclerotic stroma. The nodules showed round to slit-like vascular spaces with numerous red blood cells. The internodular stroma consisted of dense fibrous tissue with scattered plump myofibroblasts and lymphoplasmacytic cells. These distinctive features lead to the diagnosis of SANT Results (if a Case Study enter NA) SANT possessed characteristic histologic features with distinctive immunohistochemistry (IHC). IHC reveals three different types of vessels within the nodules: 1. Small veins (CD34- CD31+ CD8-); 2. Sinusoids (CD34- CD31+ CD8+); and 3. Capillaries (CD34+ CD31+ CD8-). All 3 vessels are negative for CD21/CD35 and CD68. Hemangioma and littoral cell angioma are two frequent vascular tumors in the spleen that should be differentiated. Both lesions lack microscopic features of SANT and have only a single type of vessels. The vessels in hemangioma are (CD31+ CD34+ CD8-); while in littoral cell angioma they are (CD31+ CD34- CD8- CD21+ CD68+) Conclusion There are no specific clinical or radiologic findings for SANT. It is important to recognize these characteristic features and to differentiate it from other benign and malignant lesions, such as angiosarcoma. A thorough histopathologic examination and IHC are helpful to make the correct diagnosis

Inflammatory pseudotumor of frontal sinus mimicking an aggressive malignancy: a rare case with diagnostic challenge on fine needle aspiration

Abstract Introduction/Objective Inflammatory pseudotumor (IPT) of sinonasal tract is a rare disease that sometimes mimicks malignancy in radiographic findings. Diagnosis of IPT on fine needle aspiration (FNA) is challenging due to limited cellularity and lack of architectural evaluation. Methods/Case Report Patient is a 59-year-old female presented with left front head swelling, facial pain and pressure. Imaging demonstrated a 3.0 cm hypermetabolic frontal sinus mass with osseous erosion through the calvaria table and deviating the adjacent dura, suspicious for malignancy. Also, an incidental 6.8 cm renal mass was identified and was proven to be clear cell renal cell carcinoma. FNA from frontal sinus showed loosely cohesive atypical cells with prominent nucleoli and occasional mitotic activity mixed with lymphoplasmacytic inflammation and eosinophils. Extensive immunostains showed that the lesional cells were only weakly stained for CD10 and desmin. Because of prominent cytologic atypia and radiological concerning for malignancy, FNA was diagnosed as malignancy not further classified. The patient underwent frontal sinus resection and the surgical specimen showed spindle cell proliferation surrounded by reactive woven bone with plump osteoblasts in a myxocollagenous stroma containing mixed lymphoplasmacytic cells and eosinophils. The spindle cells are positive for actin and calponin, negative for ALK. The spindle cells and plump osteoblasts corresponded to the atypical cells observed on FNA. The overall finding is consistent with IPT, although inflammatory myofibroblastic tumor cannot be completely ruled out. During follow up, the patient developed metastatic renal cell carcinoma in lung. Her frontal sinus lesion was stable for 17 months after surgery. Results (if a Case Study enter NA) NA Conclusion IPT of sinonasal tract is a rare lesion that sometimes demonstrate aggressive radiologic features. FNA from IPT poses a diagnostic challenge and can be misinterpreted as malignancy due to prominent cytologic atypia. Being aware of this rare entity helps avoid misdiagnosis and triggers the request for core biopsy during onsite evaluation.

Establishment of the Bcwm.2 Cell Line As a BTK-Inhibitor Resistant, BCL2 Inhibitor Sensitive in Vitro and In Vivo Study Model for Waldenström's Macroglobulinemia

Background: Waldenström's macroglobulinemia (WM) is an indolent B-cell lymphoproliferative disorder characterized by bone marrow (BM) infiltration with lymphoplasmacytic lymphoma and monoclonal immunoglobulin M (IgM) production. Mutations in MYD88 are present in 95-97% of WM patients. Deletions involving chromosome 6q (del6q) are found in up to 50% of WM patients, and include genes that regulate MYD88, BCL2 and apoptotic signaling. Cell lines can play a pivotal role as disease models, contributing to a comprehensive understanding of WM biology and advancing therapeutic strategies. The availability of cell lines for the study of WM remains limited, and none demonstrate del6q. Patient and Methods: We developed and characterized a novel cell line (BCWM.2) from long-term cultures of CD19 + selected BM lymphoplasmacytic cells from a symptomatic, treatment naive WM patient who then received ibrutinib monotherapy on a clinical trial. The patient attained a major response to treatment, and after 2 years progressed. The patient underwent serial bone marrow biopsies, and extensive genomic and transcriptome analysis of his tumor during the study, and the corresponding cell line established at baseline. An in vivo xenograft mouse model of BCWM.2 was also established in NOD SCID mice, and the origin of the xenografted tumor was confirmed by genomic sequencing and immunohistochemistry. Results: BCWM.2 cells exhibited morphologic and immunophenotypic characteristics resembling lymphoplasmacytic cells and demonstrated robust propagation when co-cultured with HS-5 stromal cells in IMDM medium supplemented with 20% FBS. Flow cytometric analysis revealed that BCWM.2 exhibited an immunophenotype consistent with the source WM patient. Whole genome sequencing demonstrated that both BCWM.2 cells and original patient WM cells carried somatic activating mutation in MYD88 (S243N) and shared trisomy in chromosomes 3 and 12, heterozygous deletion of 6q, and amplification of 6p. Notably, a novel mutation in the SRC family member LYN (I297N; T>A), a component of BCR, was identified in BCWM.2 but not the original patient tumor. The I297N mutation found in the regulatory hinge region is predicted to cause activation of LYN. At time of progression on ibrutinib, the dominant clone that emerged in the patient's tumor also carried the I297N mutation. Additionally, mutated genes in BCWM.2 included histone deacetylase HDAC5, tumor suppressor RUNX3, B-cell transcriptional activator SPI1, and AKAP9 (A-Kinase Anchoring Protein 9). Transcriptome analysis showed shared expression patterns between BCWM.2 and patient tumor samples, including diminished gene expression of chromosome 6q. Drug response testing revealed that BCWM.2 cells did not respond to the BTK-inhibitors ibrutinib, zanubrutinib or pirtobrutinib but were sensitive to the BCL2 inhibitor venetoclax. Furthermore, BCWM.2 cells readily engrafted in NOD-SCID mice by direct subcutaneous injection of 2 x 10^6 cells/mouse. Tumor growth (~500 mm^3) was observed in the mice four weeks post-inoculation. Importantly, follow-up evaluations demonstrated serial increases in human IgM levels in the mouse sera post-engraftment. Moreover, BCWM.2 engraftment was confirmed by immunohistochemistry with tumors exhibiting intermediate lymphoid cell morphology with plasmacytoid differentiation, CD20 and MUM1 expression, clonality for lambda light chain and IgM heavy chain, 60% KI67 staining. Whole exome sequencing of engrafted tumors further confirmed the presence of the MYD88 S243N and LYN I297N mutations detected in the cell line and the patient at the time of ibrutinib progression. Conclusions: BCWM.2 represents a novel, BTK-inhibitor resistant, BCL2 inhibitor sensitive WM cell line that demonstrates MYD88 (S243N) and LYN (I297N) somatic activating mutations, and deletions of 6q. BCWM.2 thereby provides an important new disease appropriate cell model for the in vitro and in vivo study of WM, including the development of targeted therapies for this disease.

Quantitative MYD88 L265P Analysis Represents a Powerful Tool for Assessing Disease Response and Evaluating Clinical Trial Performance in Waldenstrom's Macroglobulinemia

Serum IgM measurements represent the current standard for assessing changes in disease burden in Waldenström's Macroglobulinemia (WM). Many agents used to treat WM can significantly affect serum IgM levels without impacting the underlying burden of clonal lymphoplasmacytic cells thereby producing discordant findings. Such agents can raise (CD20-directed monoclonal antibodies, IMiDs), or lower (BTK-, proteasome-, MTOR- inhibitors) serum IgM levels, and impact categorical response assessment. Somatic mutations in MYD88 are found in 95-97% of WM patients, and support tumor growth through activation of multiple pro-survival pathways that include HCK/BTK, SYK and ERK. Nearly all MYD88 mutations in WM are of the L265P variant. Previous studies by us and others have shown that serial quantitative measurements of both bone marrow (BM) and peripheral blood (PB) MYD88 L265P (c.978 T>C) by allele-specific PCR can be used to assess changes in underlying BM disease burden (Blood 121:2051-2058; Leukemia 28:1698-1704). However, the utility of using quantitative allele-specific MYD88 L265P (qMYD88 L265P) analysis has not been studied in prospective clinical trials. As such, we performed a comprehensive study of qMYD88 L265P response assessment utilizing BM and PB CD19-selected tissue across 5 prospective clinical studies in WM: Ixazomib, Dexamethasone and Rituximab (IDR; NCT02400437) Ibrutinib monotherapy (IBR; NCT02604511); Venetoclax monotherapy (VEN; NCT02677324); Ibrutinib plus Ulocuplomab (IBR/ULO; NCT03225716); and Ibrutinib plus Venetoclax (IBR/VEN; NCT04273139). Changes in MYD88 L265P ΔCt were assessed as reported above with ΔCt = Mutant Ct - Wild-type Ct, and higher ΔCt values indicating a lower mutant allele burden, with each ΔCt unit reduction representing a 50% decrease in mutant MYD88 L265P burden. Changes in MYD88 L265P ΔCt were compared to changes in underlying BM disease burden and categorical response assessment using the current (IWWM-11) response criteria (Semin Hematol. 60:97-106). Across all five trials, BM (r=0.52; p<0.001) and PB (r=0.43; p<0.001) MYD88 L265P ΔCt changes from baseline were highly correlated at best response with corresponding changes in underlying BM disease burden determined by repeat BM biopsies. As shown in Fig. 1, comparing changes from baseline in BM MYD88 L265P ΔCt assessments across studies showed marked differences, with greatest reductions observed in patients treated with IBR/VEN, IDR, and VEN alone, than for those treated with IBR alone or IBR/ULO. Similar findings were also observed for corresponding PB MYD88 L265P ΔCt assessments from baseline, with changes in PB MYD88 L265P ΔCt strongly correlating with those of BM MYD88 L265P ΔCt findings across all 5 clinical trials (r=0.67; p<0.001), thereby signifying the ability to use PB MYD88 L265P ΔCt assessments to evaluate treatment responses. We next compared findings from BM and PB MYD88 L265P ΔCt to changes from baseline in serum IgM levels across all 5 trials. At best response, major categorical responses denoted by >50% reduction in serum IgM using IWWM-11 criteria showed commensurate decreases in BM and PB MYD88 L265P ΔCt from baseline in patients receiving IBR/VEN, IDR and VEN alone ( Fig. 2). In contrast, minimal changes in BM and PB MYD88 L265P ΔCt from baseline were observed at best response for most major responders on IBR or IBR/ULO, including individuals who achieved very good partial responses denoted by >90% decrease in IgM by IWWM-11 criteria. In this first prospective evaluation of BM and PB qMYD88 L265P response assessment, we show that both BM and PB L265P qMYD88 analysis can provide more accurate assessment of treatment related changes in disease burden over the current standard of IgM response assessment alone, and can be used to more robustly evaluate clinical trial performance byidentifying treatments or regimens that produce more meaningful tumor reductions in WM patients.

Lymphoplasmacytic Lymphoma: An Atypical Presentation with IgG Monoclonal Gammopathy

Introduction Lymphocytic lymphoma (LPL) is a rare type of low-grade mature B-cell non-Hodgkin lymphoma, characterized by a monoclonal population of B lymphocytes, lymphoplasmacytic cells, and plasma cells. In around 95% of LPL cases, the serum immunoglobulin M (IgM) paraprotein is increased, which is correlated to Waldenstrom's Macroglobulinemia (WM), a clinicopathological disease. Only around 5% of LPL cases are associated with the serum paraproteins immunoglobulin G (IgG) or immunoglobulin A (IgA), or light chains alone, or are not linked to a paraprotein. Non-IgM LPLs have a wide range of clinical and pathological features, and MYD88 L265P mutations can occur, though at a lower frequency than WM. Hence, MYD88 testing is advised for prospective therapeutic purposes. Case Presentation A 69-year-old male was referred to a hematologist for uncontrolled epistaxis and periorbital edema. On initial workup, he had high total protein, elevated globulin, hypoalbuminemia, anemia, and proteinuria. Further investigation revealed a high IgG level with low IgM, IgA, and complement levels. Serum Protein Electrophoresis (SPEP): Increased total protein, decreased alpha two and beta globulins with a large monoclonal protein peak migrating in the gamma region, which accounts for 4.77 g/dl of the total 5.38g/dl gamma. Elevated Kappa Quantitative Free Light Chains of 355.39 (3.30 - 19.40mg/L), Decreased Lambda Quantitative Free Light Chains of 1.51 (5.71 - 26.30mg/L), Elevated Kappa Lambda Free Light Chains Ratio of 235.36 (0.26 - 1.65). Serum ImmunoFixation Electrophoresis demonstrated IgG-type kappa monoclonal protein with an additional faint band in IgG kappa. X-Ray skeletal survey showed a possible small lytic area in the inferior aspect of the C2 vertebral body, prompting him to have a cervical spine MRI which revealed no lytic lesions but an 18 mm vertebral body hemangioma inside T2. Molecular testing was positive for MYD88 Mutation c.794T>C (p. L265P) and negative for CXCR4 mutation. Plasma cell myeloma prognostic panel and chromosome analysis were normal. Flow cytometry of bone marrow aspirate showed a kappa light chain restricted plasma cell population (1.6% of total cells) with the following immunophenotype: positive for CD138, CD38, CD45, and negative for CD19, CD20, CD56, CD 117, and lambda light chains. The B-cell population showed kappa light chain restriction with the following immunophenotype: positive for CD19, CD20, and kappa light chains and negative for CD5, CD10, CD11c, CD23, and lambda light chains (Image 2). PET-CT of the whole body was negative for the extension of the disease. Transfusion with the two least incompatible PRBCs had little effect. However, plasmapheresis significantly improved his hemoglobin level by less than 7g/dl. A bone marrow biopsy revealed he had LPL with IgG Monoclonal Gammopathy (Image 1). He received one cycle of CyBorD (Cyclophosphamide, Bortezomib, Dexamethasone), followed by seven cycles of KCD (Carfilzomib, Cyclophosphamide, Dexamethasone) and Rituximab. The patient was diagnosed with low-grade B cell lymphoma with plasmocytic differentiation/lymphoplasmacytic lymphoma, with MYD88 mutation c.794T>C (p. L265P) positivity and CXCR4 mutation negativity. After plasmapheresis, the IgG level dropped to 1958. Follow-up SPEP revealed decreased alpha2 and beta globulins, decreased free lambda light chains, and increased K/L ratio. The patient was treated with Acalabrutinib, and his anemia, epistaxis, and coagulopathy resolved. Repeat PET-CT scan revealed no evidence of illness progression. Discussion LPL is not always linked with IgM monoclonal gammopathy; it can also be associated with IgG or IgA monoclonal gammopathy, light chains alone, or no monoclonal paraprotein. Non-IgM LPL has a high prevalence of extramedullary involvement, a lower rate of MYD88 mutation, and few hyper viscosity symptoms. The MYD88 mutation does not allow WM and Non-IgM LPL to be distinguished from other lymphoproliferative disorders with similar clinical and immunophenotypic features. The case described is unique as the patient has high levels of IgG (11,200) at presentation. In contrast to our patient, who has LPL with IgG Monoclonal gammopathy, approximately 95 percent of LPL patients have IgM Monoclonal gammopathy, which corresponds with WM. As a result, clinicians should be on the lookout for LPL that lacks an IgM Monoclonal Paraprotein.

A High-Throughput Screen Identifies New Drugs for the Treatment of Lymphoma

Waldenström Macroglobulinemia (WM) is an incurable lymphoma. Despite the advances in molecular characterisation of WM and the development of novel drugs such as Bruton tyrosine kinase inhibitors, rates of deep response with complete remission remain very low at ~ 30%. Therefore, newer and more effective treatments are needed for WM. Novel drug development is hampered by high costs and failure rates, and long development times. These limitations and the unmet need for anti-cancer therapies have created a growing interest in repurposing drugs that are already approved for other indications to manage cancer. To identify safe and effective therapeutic options for the treatment of WM, we performed an unbiased high-throughput in vitro drug screening at the Australian National University Centre for Therapeutic Discovery. We used a cell line derived from a patient with WM called MWCL-1 to discover drug candidates with cytotoxicity potential. We treated these cells with 2,393 compounds approved by the Food and Drug Administrator (FDA) using five different concentrations and measured the cell viability using Cell Titre Glo assay which quantifies the amount of ATP released from the viable cells. In addition, we performed live cell imaging using Incucyte to confirm the cytotoxic potential of lead compounds. Furthermore, immunoblotting was used to identify the programmed cell death pathway induced by the lead compounds. Our high-throughput screen of 2,393 compounds from the FDA library identified 33 drug candidates which substantially reduced the viability of MWCL-1 cells as compared to vehicle control (dimethyl sulfoxide). This screen yielded a hit rate of 1.3%, based on the cut-off score of IC 50 2 μM or less. Of these hits, we identified five highly potent compounds with an IC 50 of less than 0.1 μM ( Fig. 1A). We confirmed the cytotoxicity potential of these lead compounds and found that all five compounds reduced the viability of MWCL-1 cells as early as 12 hours after treatment, with the highest reduction in viability observed at 72 hours. Furthermore, these compounds substantially reduced the viability of another WM cell line called BCWM.1 which morphologically and phenotypically resembles lymphoplasmacytic cells of WM. Importantly, we observed that these compounds reduced the viability of bone marrow-derived primary lymphocytes from a patient with WM as compared to vehicle control ( Fig. 1B). The compound SN01005979 was most effective and exerted a similar cytotoxic potential as standard treatment Doxorubicin ( Fig. 1B). To characterize the mechanisms of action by which these lead compounds kill MWCL-1 and BCWM.1 cells, we performed immunoblotting and tested the activation of programmed cell death pathways including caspase-1, gasdermin (GSDM)-D, GSDME (pyroptosis), caspase-8 (extrinsic apoptosis), caspase-9 (intrinsic apoptosis), caspase-3, -6, and -7 (executioners of apoptosis), and phosphorylation of MLKL (necroptosis). We found that these compounds selectively induce caspase-3-dependent cleavage of GSDME. In summary, using a high throughput screen, we identified novel drug candidates with potent cytotoxic activity against WM. Our identification of key molecules targeted by these drug compounds could pave the way for the treatment of tumours expressing caspase-3 and GSDME. Moreover, our results offer new insights into the mechanism of certain FDA-approved drugs and could help in the development of safer and more effective cancer chemotherapy against WM and potentially other cancers. Future studies are required to test the tumour-killing potential of these drugs in vivo using mouse and humanised mouse models of WM.

Mutational Landscape of Bone Marrow CD19 and CD138 Cells in Waldenström Macroglobulinemia (WM) and IgM Monoclonal Gammopathy of Undetermined Significance (IgM MGUS)

Background Waldenström's Macroglobulinemia (WM) is an incurable B-cell neoplasm characterized by serum monoclonal immunoglobulin M (IgM) and clonal lymphoplasmacytic cells infiltrating the bone marrow (BM). Smoldering WM (sWM) is the asymptomatic/indolent form with a high risk of progressing to symptomatic WM requiring treatment whereas IgM monoclonal gammopathy of undetermined significance (IgM MGUS) is an early precursor stage of WM. Despite recurrent and activating mutations, including MYD88, CXCR4, ARID1A, KMT2D, and CD79B have been identified, the genetic basis for WM and the risk of progression of IgM MGUS to WM remain to be fully elucidated. Methods Based on the mutational profiling of WM and our previous wide transcriptome analyses on BM CD19+ and CD138+ cells of patients with WM and IgM MGUS, we decided to investigate the mutation status of these patients as follows: WM (n=10), sWM (n=7), and IgM MGUS (n=5), by performing high throughput targeted AmpliSeq next generation sequencing on 117 target genes potentially involved in B-cell lymphomagenesis and in the risk of progression of IgM MGUS to WM (Trojani A. et al. Cancers, 2021). Results We identified genetic aberrations in multiple genes, including previously described classic mutations in MYD88 (L260P alias L265P) found in 82.3% (14/17) of WM/sWM patients and in 60% (3/5) of IgM MGUS subjects. The CXCR4 mutation (S338Ter) was detected in 23.5% of CD19+ cells of WM patients, whereas it was absent in IgM MGUS subjects. Interestingly, we also identified new mutated genes, including WNK2 somatic mutations affecting 47% of WM patients, for which a recurrent allelic variant (V1635Ter) was observed, and BCL9 with a recurrent frameshift variant (P516Lfs) identified in 29.4% of WM patients exclusively in the CD19 cell fraction. The BCL9 (P516Lfs) variant was also detected in the B cells of one IgM MGUS patient. Moreover, sequencing evaluation revealed recurrently frameshift or missense mutations involving NFKB2 (L473Afs), PTPN13 (P1546Tfs), CARD11 (S622del), KMT2C (I823T), and ATM in WM and IgM MGUS patients (Figure 1). Of interest, KMT2C (also known as MLL3) exhibited a somatic hypermutated phenotype in both CD19+ and CD138+ cells of WM and IgM MGUS samples. The KMT2C mutations were not mutually exclusive with those involving KMT2D in our cohort of patients. Conclusion The present genomic analysis revealed new insights into the mutational landscape of Waldenström Macroglobulinemia, providing evidence of the recurrence of some variants in subjects with IgM MGUS as well. Notably, we uncovered new genetic mutations with somatic variants recurrently observed (n≥3) in KMT2C, WNK2, BCL9, PTPN13, CARD11 and NFKB2 genes. These recurring somatic events provide a genomic basis for future research and a better understanding of the WM pathogenesis as well as the risk of transformation of IgM MGUS to WM.

Changes in Methylation and Chromatin Accessibility Underlie Subtype Classification and Disease Evolution in Waldenström's Macroglobulinemia

Background: We previously identified three subtypes of Waldenstrom's Macroglobulinemia (WM): B-cell like (BCL), Plasma cell like (PCL), and an intermediate group enriched for early/smoldering WM from which the other two subtypes evolved (Hunter et al, ASH 2022). Diffusion pseudo-time (DPT) analysis suggested all WM samples could be placed on a shared evolutionary path independent of subtype, and when samples were separated into Early and Late DPT values, it mirrored disease progression. The role of epigenetic dysregulation that underlies subtype classification and disease evolution remains poorly understood in WM. Methods: We therefore performed chromatin availability analysis using ATACSeq and bisulfite sequencing of WM patients. ATAC-Seq libraries were constructed from 37 CD19+ BM cells from treatment-naive WM patients along with 6 paired CD19+CD27- and CD19+CD27+ selected healthy donor (HD) peripheral blood (PB) controls and 3 HD CD138+ plasma cell (PC) samples. Enhanced reduced representational bisulfite sequencing (ERRBS) was also performed on 65 MYD88 mutated and 13 MYD88 wild type (WT) WM patients using CD19-selected BM lymphoplasmacytic cells. For 11 WM MYD88 mutated patients, CD138+ cells were also selected. In addition ERRBS was also performed on paired CD19+ and CD138+ selected samples from 5 IgM multiple myeloma (MM) patients, 6 paired CD19+CD27- and CD19+CD27+ selected healthy donor (HD) peripheral blood cells; 8 HD CD138+ selected PC; as well as MYD88 mutated BCWM.1, BCWM.2, MWCL-1, RPCI-WM1, OCI-Ly3, TMD-8, HBL-1 and SU-DHL2 cells; MYD88 wild-type OCI-Ly7, OCI-Ly19, Ramos B-cells. To infer 5-hydroxymethylcytosine (5HMC) levels, oxidative bisulfite sequencing was also performed for 73 samples including the HD, MM, WT and WM CD19/138 pairs. All ATAC-Seq and 37 of the WM ERRBS samples were part of our multi-omic study that included 253 treatment naïve patients who underwent whole exome and RNASeq sequencing. Results: A UMAP projection of the CpG ERRBS data clustered WM patients into two distinct groups ( Figure 1). One group clustered directly with HD Memory B-cells (MB) and was greatly enriched for CXCR4 mutated WM patients. The other WM group clustered with IgM MM patients and was largely CXCR4 WT. The findings are consistent with the BCL and PCL WM subtypes, which were confirmed by a perfect assignment correlation with our larger multi-omic data set wherein these subtypes were defined. Notably, BCWM.1, BCWM.2 and MWCL-1 WM cell lines clustered with the WM samples. The 5HMC data displayed no clear clustering of the patient samples but clearly separated all HD samples from those of WM and IgM MM samples, consistent with a role for 5HMC dysregulation in oncogenesis. Differential methylation analysis showed differences by MYD88 and CXCR4 mutation status, deletions in Chr6q, familial history for WM, WM subtype, and stratification by early and late DPT values. Notably, the only comparison that did not yield any differences was WM CD19+ to WM CD138+, suggesting that this may not be a meaningful epigenetic distinction in WM. Similar comparisons were performed on the ATAC peaks. Differential chromatin accessibility was noted near many of the corresponding differentially expressed genes. ATAC peak coverage significantly correlated with the expression of top genes. This was particularly true for WM subtype and DPT comparisons ( Table 1). DNA sequences from differentially accessible peaks between BCL and PCL subtypes were also evaluated for relative TF motif enrichment in open vs. closed chromatin revealing PAX5, FUBP1, and ZNF121 enrichment in BCL subtypes using PCL subtype peaks as a background control. TFs REL, SP1, SPIB, BC11A and JUN were enriched PCL subtype compared with BCL subtype. Correlation between DPT associated genes revealed two clear groups, one associated with stem cell and pre-B-cell genes (Group 1) and the other with inflammatory, myeloid, and T-cell genes (Group 2). Motif analysis of differential peaks correlating with genes in each group demonstrated comparative enrichment for MYC, MXI1, and E2F2 in group 1 while RUNX1, NFKB1, and ATF1 were in enriched in group 2. Conclusions: This is the first independent validation of our previously reported multi-omic driven WM subtype classification. The studies underscore that epigenetic differences underlie the biology of WM subclassification and support a strong role for epigenetic changes driving WM evolution.

A 35-year-old male with Waldenstrom Macroglobulinemia

Waldenstrom macroglobulinemia is one type of non- Hodgkin lymphoma that presents with a wide range of clinical features mainly due to secretion of the IgM paraprotein and infiltration of lymphoplasmacytic cells. Patients with Waldenstrom macroglobulinemia may experience fatigue, unexplained weight loss, enlarged lymph nodes, abdominal swelling, weakness, nose bleeding, blurring of vision etc. Waldenstrom macroglobulinemia is a disease of elderly individuals. The median age at diagnosis is 65 years, with a slight male predominance. We reported a case of a 35-yearold male who presented with fever, abdominal pain, loose motion and epistaxis. Examination revealed cervical and inguinal lymphadenopathy with hepatosplenomegaly. Investigation revealed diffuse lymphocyte infiltration on bone marrow study . Protein electrophoresis showed monoclonal gammopathy with high serum IgM level. On the basis of clinical features and investigation reports finally we diagnosed that, this was a rare case of Waldenstrom macroglobulinemia in a young patient. The patient was transfused 5 units of whole blood and was treated following standard treatment protocol with dexamethasone, Bortezomib and G-CSF. Unfortunately, patient died 3 weeks after initiation of treatment. J Bangladesh Coll Phys Surg 2023; 41(4): 325-328

Determination of Helicobacter heilmannii in cats by real time polymerase chain reaction and histopathology

Helicobacter species such as Helicobacter heilmannii, Helicobacter pylori, Helicobacter felis, Helicobacter bizzozeronii, Helicobacter salomonis have been identified in cats and dogs, and research suggesting that these species may be zoonotic agents have increased in recent years. The aim of this study is to reveal the presence of H. heilmannii in stomach and liver tissues taken during necropsies of domestic, stray and shelter cats by real-time PCR and histopathology and to compare histopathological findings and real-time PCR results. The material of the study consisted of stomach and liver tissues taken from 41 cats who died from different causes and were necropsied. DNA of H. heilmannii was determined in the stomach tissues of 36 cats and the liver tissues of 24 cats in the study conducted with real-time PCR using specific primers of H. heilmannii. Epithelial degeneration in the stomach, fibrosis and oedema in the lamina propria and lymphoplasmacytic cell infiltration were detected histopathologically in the cats diagnosed with gastritis. Eight cats were positive in Hematoxylin-Eosin staining and nineteen cats were positive in the staining with Warthin Starry of the sections, in terms of Helicobacter-like microorganisms. Microscopically, dissociation of the remark cords and hydropic degeneration in hepatocytes and mononuclear cell infiltrations in some sections were determined in the livers. In conclusion, with this study, it was understood that real-time PCR analyses are very useful in determining H. heilmannii in cats. However, histopathological examinations are necessary to associate the presence of bacteria with the development of the disease.

A Case of Bing-Neel Syndrome Presenting Like Giant Cell Arteritis.

A 55-year-old woman presented with new-onset headache, scalp tenderness, shoulder arthralgias, night sweats, and loss of appetite. She was diagnosed with giant cell arteritis by her primary care physician and commenced on oral corticosteroids. However, her headache, scalp tenderness, and night sweats persisted. She then developed right Horner syndrome and trigeminal hypoesthesia. Extensive blood work-up revealed mildly elevated inflammatory markers and a paraproteinemia. Subsequent bone marrow biopsy showed lymphoplasmacytic lymphoma, with 10% of hemopoiesis, and staging led to the diagnosis of Waldenstrom macroglobulinemia without nodal or central nervous system (CNS) lesions. Immunohistochemical staining of a temporal artery biopsy showed perivascular lymphoplasmacytic cells and paraprotein deposits. She was diagnosed with CNS involvement of her macroglobulinemia-Bing-Neel syndrome (BNS). Identification of rare CNS involvement of lymphoma is challenging when a patient is already on steroid immunosuppression. In the absence of clear diagnostic criteria, the rare and heterogenous BNS remains a clinical diagnosis.

Waldenström macroglobulinemia: a review of pathogenesis, current treatment, and future prospects.

Waldenström macroglobulinemia (WM) is a chronic B-cell lymphoproliferative disorder characterized by lymphoplasmacytic cell overgrowth in the bone marrow and increased secretion of IgM immunoglobulins into the serum. Patients with WM have a variety of clinical outcomes, including long-term survival but inevitable recurrence. Recent advances in disease knowledge, including molecular and genetic principles with the discovery of MYD88 and CXCR4 mutations, have rapidly increased patient-tolerable treatment options. WM patients may benefit from chemotherapy regimens that include rituximab-based regimens, alkylating drugs, proteasome inhibitors, monoclonal antibodies, and drugs targeting Bruton tyrosine kinase inhibitors. In light of these advancements, patients can now receive treatment customized to their specific clinical characteristics, focusing on enhancing the depth and durability of their response while limiting the adverse effects. Despite the rapidly developing therapeutic armament against WM, a lack of high-quality evidence from extensive phase 3 trials remains a significant challenge in the research. We believe clinical outcomes will keep improving when new medicines are introduced while preserving efficacy and minimizing toxicity.

Follicular cholangitis mimicking a common bile duct cancer: a case report

BackgroundFollicular cholangitis (FC) is a benign bile duct disease that was first reported 2003. Pathologically, it is characterized by lymphoplasmacytic infiltration with multiple lymphoid follicle formations under the mucosal layer of the biliary tract. However, as this disease is extremely rare, little is known about its etiology and pathogenesis.Case presentationA 77-year-old woman was diagnosed with middle bile duct stenosis and potential increases in alkaline phosphatase (ALP) and γ-glutamyl transpeptidase levels (γ-GTP). Carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9) and IgG4 levels were all within the normal limits. Contrast-enhanced computed tomography (CE-CT) and magnetic resonance imaging (MRI) revealed bile duct dilation from intrahepatic to upper common bile duct and an irregular mass lesion in distal bile duct. Additionally, multiple overlapping leaf-like folds were detected. 18F-fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG-PET/CT) did not demonstrate fluorodeoxyglucose uptake. Subtotal stomach-preserving pancreaticoduodenectomy with regional lymph node dissection was performed because common bile duct cancer could not be ruled out. The resected specimen showed diffuse homogeneous middle bile duct wall thickening. Microscopically, the lesion exhibited thick fibrosis with several invaded lymphoplasmacytic cells, and lymphoid follicle formations were detected under the mucosal layer. Immunohistochemical staining (IHC) revealed positive for CD3, CD4, CD20 and CD79a, and these findings led to a final diagnosis of FC. The patient has not experienced recurrence to date (42 months postoperatively).ConclusionsCurrently, accurate preoperative diagnosis of FC is difficult. More cases must be accumulated to generate additional knowledge on its precise diagnosis and proper treatment.