Bone Marrow Histopathology in the Diagnostic Evaluation of Splenic Marginal-zone and Splenic Diffuse Red Pulp Small B-cell Lymphoma: A Reliable Substitute for Spleen Histopathology?

Splenic Diffuse Red Pulp Small B-Cell Lymphoma with Overlapping Clinical and Immunophenotypic Features with Hairy Cell Leukaemia: A Case Report and a Review of the Literature

BACKGROUND

Splenic B-cell lymphomas and leukaemias include hairy cell leukaemia, splenic marginal zone lymphoma, splenic diffuse red pulp small B-cell lymphoma, and splenic B-cell lymphoma/leukaemia with prominent nucleoli. The main diagnostic challenge is to differentiate between splenic B-cell lymphomas and leukaemias due to highly overlapping clinical, morphologic, and phenotypic features in the absence of splenectomies for diagnostic purposes.

CASE PRESENTATION

We describe a case of a 78-year-old woman who presented with weight loss and was subsequently found to have pancytopenia, lymphocytosis, and splenomegaly. Peripheral blood smear showed a homogenous population of small- to medium-sized lymphocytes having oval nuclei, condensed chromatin, and villous cytoplasmic projections. Bone marrow showed B-cell infiltrate in a predominantly intrasinusoidal pattern. Except for cyclin D1 and BRAF, the immunophenotype was similar to that of hairy cell leukaemia. This was further supported by the lack of BRAF p.V600E mutation by polymerase chain reaction. A diagnosis of splenic diffuse red pulp small B-cell lymphoma was thus favored based on the lack of cyclin D1 expression and pattern of infiltration in the bone marrow biopsy.

CONCLUSIONS

Awareness of this infrequent clinical presentation and immunophenotype of splenic diffuse red pulp small B-cell lymphoma is crucial for diagnosis and devising appropriate therapeutic strategies for the patient.

Intrasinusoidal bone marrow involvement in mantle cell lymphoma: a case series with review of the main differential diagnoses

Intrasinusoidal bone marrow involvement is an infrequent histological pattern observed in a limited number of B and T cell lymphomas. Mantle cell lymphoma is a biologically and prognostically heterogeneous B cell lymphoma that frequently involves the bone marrow, with interstitial, nodular-paratrabecular, or diffuse patterns. Intrasinusoidal bone marrow involvement has been described only anecdotally in this lymphoma. Here, we describe the clinical, histopathological, and molecular features of four patients diagnosed with advanced-stage mantle cell lymphoma, showing intrasinusoidal bone marrow involvement, and other peculiar immunophenotypical features. As similar cases may represent a relevant issue in bone marrow diagnostic histopathology, we also reviewed the literature to discuss differential diagnoses of B and T cell lymphomas with intrasinusoidal bone marrow involvement.

The many faces of nodal and splenic marginal zone lymphomas. A report of the 2022 EA4HP/SH lymphoma workshop

Session 3 of the lymphoma workshop of the XXI joint meeting of the European Association for Haematopathology and the Society for Hematopathology took place in Florence, Italy, on September 22, 2022. The topics of this session were splenic and nodal marginal zone lymphomas, transformation in marginal zone lymphomas, and pediatric nodal marginal zone lymphomas and their differential diagnosis as well as related entities. Forty-two cases in these categories were submitted to the workshop, including splenic lymphomas (marginal zone and diffuse red pulp lymphomas), transformed marginal zone lymphomas (splenic and nodal), nodal marginal zone lymphomas with increased TFH-cells, and pediatric nodal marginal zone lymphomas. The case review highlighted some of the principal problems in the diagnosis of marginal zone lymphomas, including the difficulties in the distinction between splenic marginal zone lymphoma, splenic diffuse red pulp lymphoma, and hairy cell leukemia variant/splenic B-cell lymphoma with prominent nucleoli which requires integration of clinical features, immunophenotype, and morphology in blood, bone marrow, and spleen; cases of marginal zone lymphoma with markedly increased TFH-cells, simulating a T-cell lymphoma, where molecular studies (clonality and mutation detection) can help to establish the final diagnosis; the criteria for transformation of marginal zone lymphomas, which are still unclear and might require the integration of morphological and molecular data; the concept of an overlapping spectrum between pediatric nodal marginal zone lymphoma and pediatric-type follicular lymphoma; and the distinction between pediatric nodal marginal zone lymphoma and "atypical" marginal zone hyperplasia, where molecular studies are mandatory to correctly classify cases.

Early progression and transformation of a splenic diffuse red pulp small B-cell lymphoma with NOTCH1, ARID2, CREBBP, and TNFRSF14 gene mutations

Splenic diffuse red pulp small B-cell lymphoma (SDRPL) is a rare entity. Diagnosis is typically achieved with splenectomy and most patients remain in remission after this intervention. Hemoglobin value less than 10 g/dL and NOTCH1, TP53, and MAP2K1 gene mutations at diagnosis have been associated with worse outcome. Progression after splenectomy of SDRPL is possible, although transformation to aggressive lymphoma has rarely been reported. We herein report the case of a patient formerly diagnosed with SDRPL with gene mutations involving CREBBP, NOTCH1, ARID2, and TNFRSF14 who transformed to diffuse large B-cell lymphoma six months after splenectomy.

[Splenic lymphoma, diagnosis and treatment]

Some common clinical situations, such as splenomegaly or lymphocytosis, or less common, such as autoimmune hemolytic anemia, cold agglutinin disease, or cryoglobulinemia can lead to the diagnosis of splenic lymphoma. Splenic lymphoma is rare, mainly of non-hodgkinian origin, encompassing very different hematological entities in their clinical and biological presentation from an aggressive form such as hepato-splenic lymphoma to indolent B-cell lymphoma not requiring treatment such as marginal zone lymphoma, the most frequent form of splenic lymphoma. These entities can be challenging to diagnose and differentiate. This review presents different clinical and biological manifestations suspicious of splenic lymphoma and proposes a diagnosis work-up. We extended the strict definition of splenic lymphoma (lymphoma exclusively involving the spleen) to lymphoma thant can be revealed by a splenomegaly and we discuss the differential diagnosis of splenomegaly.

Purine nucleoside analogs plus rituximab are an effective treatment choice for hairy cell leukemia-variant

Both characteristics and optimal treatment strategy for hairy cell leukemia-variant (HCL-v) remain elusive due to its rarity. We retrospectively analyzed the clinical features of HCL-v and the efficacy of first-line treatment options in a large Chinese cohort. In this study, we recruited 33 HCL-v patients (23 males and 10 females) with a median age of 59 years (range, 34-79 years). The chief complaints included abdominal mass and relative signs (67%) and abnormal complete blood count (27%). Immunophenotyping showed monoclonal B-cells positive for pan B-cell antigens and CD11c, weakly positive for CD103 and CD200, while negative for CD5, CD10, CD25, CD123, and annexin A1. No BRAF V600E mutation was detected, but TP53 abnormality was recurrent. Treatment choices included interferon-α (IFN-α) in 11 patients, chlorambucil (CLB) in 5 patients, single purine nucleoside analogs (PNA) in 3 patients, PNA plus rituximab (PNA + R) in 9 patients, and others in 3 patients. Four patients who received IFN-α or CLB treatment also underwent splenectomy. Patients who received PNA + R had a higher complete response rate (88% versus 5%, P < 0.001) and longer progression-free survival (PFS, 3-year PFS rate 42% [95% CI 1-84] vs. 16% [95% CI 3-40], P = 0.042) than those who received other regimens. Overall, HCL-v is an indolent lymphoma with unique characteristics. The PNA + R regimen is the preferred choice in the first-line treatment for HCL-v.

Myeloid Nuclear Differentiation Antigen (MNDA): an aid in differentiating lymphoplasmayctic lymphoma and splenic marginal zone lymphoma in bone marrow biopsies at presentation

The differential diagnosis between lymphoplasmacytic lymphoma (LPL) and marginal zone B-cell lymphoma, particularly splenic type (SMZL) can be challenging on onset bone marrow biopsy (BMB) since morphology and phenotype are not specific and clinical features can overlap or be mildly developed at diagnosis. The LPL-specific L265P mutation in the MYD88 gene is not available in all laboratories and genetic aberrancies identified in SMZL (del7q, mutations of NOTCH2 and KLF2) are seldom searched in routine practice. The study aim is to investigate the potential role of MNDA expression in this specific differential diagnosis. We report MNDA reactivity in 559 small B-cell lymphoma (SBCL) patients including bone marrow biopsies from 90 LPL and 91 SMZL. MYD88 p.Leu265Pro mutation status was assessed and confirmed as positive in 24 of 90 LPL cases, which served as the test set. MNDA staining was negative in 23/24 LPL cases in the test set (96%). In the 157 remaining cases (66 LPL, 91 SMZL), which served as validation set, the MYD88 p.Leu265Pro mutation was unavailable and MNDA was more frequently expressed in SMZL (p<0.00001). In addition, immunohistochemical features more consistent with SMZL (i.e. presence of CD23+ follicular dendritic cell meshworks, polytypic plasma cells, DBA44 reactivity) were more often present in MNDA positive cases (statistically significant for 2 such parameters). On the widest case-series so far published focusing on LPL and SMZL immunohistochemical diagnosis at onset on BMB, we demonstrated that MNDA expression significantly support the diagnosis of SMZL. This observation may be of particular help in cases where the MYD88 p.Leu265Pro mutational status and/or SMZL-related genetic aberrations are unavailable.

A Review on Splenic Diffuse Red Pulp Small B-Cell Lymphoma

Splenic diffuse red pulp small B-cell lymphoma (SDRPL) is a rare disease, representing <1% of all non-Hodgkin lymphomas (NHL). The most common clinical manifestations include splenomegaly, lymphocytosis, and hemocytopenia. A diagnosis of SDRPL can be challenging, as it shares multiple clinical and laboratory features with splenic marginal zone lymphoma (SMZL), hairy cell leukemia (HCL), and HCL variant (HCL-v). Obtaining splenic tissue remains the gold standard for diagnosis. In the cases where splenic tissue is not available, diagnosis can be established by a review of peripheral blood and bone marrow studies. SDRPL is characterized by a diffuse involvement of the splenic red pulp by monomorphous small-to-medium sized mature B lymphocytes effacing the white pulp. The characteristic immunophenotype is positive for CD20, DBA.44 (20 to 90%), and IgG, and typically negative for CD5, CD10, CD23, cyclin D1, CD43, annexin A1, CD11c, CD25, CD123, and CD138. The Ki-67 proliferative index is characteristically low. Cyclin D3 is expressed in the majority of SDRPL in contrast with other types of small B-cell lymphomas, thus facilitating the recognition of this disease. There is no standard treatment regimen for SDRPL. Initial treatment options include splenectomy, rituximab monotherapy, or a combination of both. Chemoimmunotherapy should be considered in patients with advanced disease at baseline or progression.

Histopathologic and Machine Deep Learning Criteria to Predict Lymphoma Transformation in Bone Marrow Biopsies

CONTEXT.—

Large-cell transformation (LCT) of indolent B-cell lymphomas, such as follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL), signals a worse prognosis, at which point aggressive chemotherapy is initiated. Although LCT is relatively straightforward to diagnose in lymph nodes, a marrow biopsy is often obtained first given its ease of procedure, low cost, and low morbidity. However, consensus criteria for LCT in bone marrow have not been established.

OBJECTIVE.—

To study the accuracy and reproducibility of a trained convolutional neural network in identifying LCT, in light of promising machine learning tools that may introduce greater objectivity to morphologic analysis.

DESIGN.—

We retrospectively identified patients who had a diagnosis of FL or CLL who had undergone bone marrow biopsy for the clinical question of LCT. We scored morphologic criteria and correlated results with clinical disease progression. In addition, whole slide scans were annotated into patches to train convolutional neural networks to discriminate between small and large tumor cells and to predict the patient's probability of transformation.

RESULTS.—

Using morphologic examination, the proportion of large lymphoma cells (≥10% in FL and ≥30% in CLL), chromatin pattern, distinct nucleoli, and proliferation index were significantly correlated with LCT in FL and CLL. Compared to pathologist-derived estimates, machine generated quantification demonstrated better reproducibility and stronger correlation with final outcome data.

CONCLUSIONS.—

These histologic findings may serve as indications of LCT in bone marrow biopsies. The pathologist-augmented with machine system appeared to be the most predictive, arguing for greater efforts to validate and implement these tools to further enhance physician practice.

Laboratory Workup of Lymphoma in Adults: Guideline From the American Society for Clinical Pathology and the College of American Pathologists

CONTEXT.—

The diagnostic workup of lymphoma continues to evolve rapidly as experience and discovery led to the addition of new clinicopathologic entities and techniques to differentiate them. The optimal clinically effective, efficient, and cost-effective approach to diagnosis that is safe for patients can be elusive, in both community-based and academic practice. Studies suggest that there is variation in practice in both settings.

OBJECTIVE.—

To develop an evidence-based guideline for the preanalytic phase of testing, focusing on specimen requirements for the diagnostic evaluation of lymphoma.

DESIGN.—

The American Society for Clinical Pathology, the College of American Pathologists, and the American Society of Hematology convened a panel of experts in the laboratory workup of lymphoma to develop evidence-based recommendations. The panel conducted a systematic review of literature to address key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation approach, recommendations were derived based on the available evidence, strength of that evidence, and key judgements as defined in the Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision framework.

RESULTS.—

Thirteen guideline statements were established to optimize specimen selection, ancillary diagnostic testing, and appropriate follow-up for safe and accurate diagnosis of indolent and aggressive lymphoma.

CONCLUSIONS.—

Primary diagnosis and classification of lymphoma can be achieved with a variety of specimens. Application of the recommendations can guide decisions on specimen suitability, diagnostic capabilities, and correct use of ancillary testing. Disease prevalence in patient populations, availability of ancillary testing, and diagnostic goals should be incorporated into algorithms tailored to each practice environment.

Flow cytometry detection of CD138 expression continuum between monotypic B and plasma cells is associated with both high IgM peak levels and MYD88 mutation and contributes to diagnosis of Waldenström macroglobulinemia

BACKGROUND

Differential diagnosis of Waldenström macroglobulinemia (WM) with other indolent B-cell malignancies is still a challenge. Here, we propose an original and simple analysis of routine flow cytometry (FCM) unraveling the characteristic ongoing plasma cell (PC) differentiation of WM tumor B-cells.

METHODS

FCM analysis of both B-cells and PC was performed on a series of 77 patients with IgM peak. MYD88 and CXCR4 mutations were studied using an allele-specific PCR and by high throughput sequencing.

RESULTS

Twenty seven (35%), 46 (58%) and 4 (5%) patients were classified as WM, IgM monoclonal gammopathy of undetermined significance (MGUS) or other B-NHL respectively. MYD88 mutation was found in 25/27 WM (93%) and in 29/46 MGUS (63%). Using FCM, monotypic B-cells were found in 27/27 WM (100%) and 34/46 MGUS (74%). Monotypic CD138pos/CD38pos PCs were detected in 23/27 WM (85%) and 25/46 MGUS (54%). Highlighting the ongoing PC differentiation of WM tumor B-cells by FCM, we evidenced a CD138 expression continuum between monotypic B-cells and PCs. This pattern remained absent in control samples and was significantly associated with higher IgM peaks (p = 6.10^-5 ) and MYD88 mutations (p = 10^-3 ) in both WM and MGUS cases.

CONCLUSIONS

FCM exploration of both B-cells and PC led to identify a CD138 expression continuum as an objective marker of ongoing PC differentiation of WM tumor cells and was strongly associated with increased IgM peak levels and MYD88 mutations. This approach could contribute to place FCM at the forefront of WM diagnosis.

Laboratory Workup of Lymphoma in Adults

OBJECTIVES

The diagnostic workup of lymphoma continues to evolve rapidly as experience and discovery lead to the addition of new clinicopathologic entities and techniques to differentiate them. The optimal clinically effective, efficient, and cost-effective approach to diagnosis that is safe for patients can be elusive, in both community-based and academic practice. Studies suggest that there is variation in practice in both settings.

THE AIM OF THIS REVIEW IS TO

develop an evidence-based guideline for the preanalytic phase of testing, focusing on specimen requirements for the diagnostic evaluation of lymphoma.

METHODS

The American Society for Clinical Pathology, the College of American Pathologists, and the American Society of Hematology convened a panel of experts in the laboratory workup of lymphoma to develop evidence-based recommendations. The panel conducted a systematic review of the literature to address key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, recommendations were derived based on the available evidence, the strength of that evidence, and key judgments as defined in the GRADE Evidence to Decision framework.

RESULTS

Thirteen guideline statements were established to optimize specimen selection, ancillary diagnostic testing, and appropriate follow-up for safe and accurate diagnosis of indolent and aggressive lymphoma.

CONCLUSIONS

Primary diagnosis and classification of lymphoma can be achieved with a variety of specimens. Application of the recommendations can guide decisions about specimen suitability, diagnostic capabilities, and correct utilization of ancillary testing. Disease prevalence in patient populations, availability of ancillary testing, and diagnostic goals should be incorporated into algorithms tailored to each practice environment.

Targeted next-generation sequencing reveals molecular heterogeneity in non-chronic lymphocytic leukemia clonal B-cell lymphocytosis

Non-chronic lymphocytic leukemia (non-CLL) clonal B-cell lymphocytosis (CBL) encompasses a heterogeneous group of hematologic disorders that are still poorly understood. To shed light on their biological aspects, we retrospectively analyzed a highly selected series of 28 patients, who had a clonal B-cell population in the peripheral blood and in the bone marrow, without evidence of lymphoma. Extended targeted next-generation sequencing revealed wide molecular heterogeneity with MYD88 (14%), PDE4DIP (14%), BIRC3 (11%), CCND3 (11%), NOTCH1 (11%), and TNFAIP3 (11%) as the most mutated genes. Mutations of MYD88 were "nonclassic" in most cases. Although some genetic lesions were overlapping with indolent lymphomas, mainly splenic B-cell lymphomas of marginal zone origin and splenic diffuse red pulp small B-cell lymphoma, the genetic profile of our non-CLL CBL series seemed to suggest that various pathways could be involved in the pathogenesis of these disorders, not mirroring any specific lymphoma entity. These data better enlighten the molecular characteristics of non-CLL CBL; however, more efforts are needed in order to improve the diagnostic process, prognostication, and clinical management.

Clinicopathologic and molecular features in hairy cell leukemia-variant: single institutional experience

Hairy cell leukemia-variant is rare. Only a small number of cases have been reported in the literature with little cytogenetic or molecular data available. In this study, we describe the clinicopathologic and genetic features of 23 patients with hairy cell leukemia-variant (16 men and 7 women) with a median age of 70 years. Most patients had splenomegaly (90%), leukocytosis (77%), and lymphocytosis (82%); no patients had monocytopenia. Histologically, the bone marrow biopsy specimens showed a mixed pattern of predominantly interstitial and lesser intrasinusoidal infiltration by leukemic cells. In bone marrow aspirate smears most cells had villous cytoplasmic features and a small nucleolus. We describe unusual sites of hairy cell leukemia-variant involvement in 4 patients, including brain, omentum, terminal ileum, and skin at the time of initial presentation. Immunophenotyping showed monotypic B-cells positive for pan B-cell antigens, CD11c, and CD103, and negative for CD25 and annexin A1. Conventional cytogenetic or fluorescence in situ hybridization analysis showed deletions of 17p13/TP53 and 11q22/ATM gene in 5/12 (42%) and 2/9 (22%) cases, respectively. Sequencing of the variable region of IGVH showed mutations (>2% deviation from germline) in 40% of the cases assessed. MAP2K1 mutation (p.C121S) was seen in 1 of 14 (7%) patients tested. No BRAF V600E mutations were detected. The patients were treated in a heterogeneous manner, but most often with therapies designed for classical hairy cell leukemia and the 5-year overall survival was 84%. In summary, hairy cell leukemia-variant exhibits a heterogeneous spectrum of clinical, morphologic, immunophenotypic, and genetic features that may overlap with classic hairy cell leukemia and other hairy cell-like B-cell neoplasms. A subset of patients can have an aggressive clinical course. In our experience MAP2K1 mutations are uncommon in this disease.

Management of relapsed/refractory marginal zone lymphoma: focus on ibrutinib

Marginal zone lymphomas (MZLs) consist of a diverse family of malignancies, which are derived from B-cells. The disease subtypes are recognized extranodal, nodal, and splenic MZLs. The disease characteristics, clinical course, and treatment vary considerably based on the site of involvement. In 2017, the US Food and Drug Administration approved ibrutinib, a first in class Bruton’s tyrosine kinase inhibitor that revolutionized the care of chronic lymphocytic leukemia patients; for, the treatment of relapsed/refractory MZL based on pivotal open-label Phase II trial demonstrated an overall response rate of 48%, with a complete response rate of 3%, median progression-free survival of 14.2 months, and median overall survival not yet reached at a median follow-up of 19.4 months. In this review, we aim to summarize the current conundrums in the management of MZL and the evolving role of ibrutinib in the treatment of MZL.

Early stages in the ontogeny of small B-cell lymphomas: genetics and microenvironment

In this review, we focus on the mechanisms underlying lymphomagenesis in chronic lymphocytic leukaemia, follicular lymphoma, mantle cell lymphoma and splenic marginal zone lymphoma. The cells of origin of these small B-cell lymphomas are distinct, as are the characteristic chromosomal lesions and clinical courses. One shared feature is retention of expression of surface immunoglobulin. Analysis of this critical receptor reveals the point of differentiation reached by the cell of origin. Additionally, the sequence patterns of the immunoglobulin-variable domains can indicate a role for stimulants of the B-cell receptor before, during and after malignant transformation. The pathways driven via the B-cell receptor are now being targeted by specific kinase inhibitors with exciting clinical effects. To consider routes to pathogenesis, potentially offering earlier intervention, or to identify causative factors, genetic tools are being used to track pretransformation events and the early phases in lymphomagenesis. These methods are revealing that chromosomal changes are only one of the many steps involved, and that the influence of surrounding cells, probably multiple and variable according to tissue location, is required, both to establish tumours and to maintain growth and survival. Similarly, the influence of the tumour microenvironment may protect malignant cells from eradication by treatment, and the resulting minimal residual disease will eventually give rise to relapse. The common and different features of the four lymphomas will be summarized to show how normal B lymphocytes can be subverted to generate tumours, how these tumours evolve and how their weaknesses can be attacked by targeted therapies.

Surgical management of splenic marginal zone lymphoma

OBJECTIVES

Splenic marginal zone lymphoma (SMZL) is a rare indolent B-cell lymphoma with variable prognosis. As a result, there is sparse knowledge on the role of splenectomy and best management approaches. We aim to explore management strategies and outcomes amongst the cohort of SMZL patients at our centre.

METHOD

A retrospective review of all splenectomies performed at a tertiary referral unit over a 23-year period was assessed. Immunohistochemical and pathological results of splenic samples, bone marrow biopsies, and peripheral blood were compiled. Operative management, surgical, and survival outcomes were assessed. Prognostic stratifications were applied and survival rates were calculated.

RESULTS

Eight cases of SMZL from a database of 693 splenectomies were identified. All patients had intermediate/high-risk disease. All patients underwent splenectomy with one patient receiving preoperative rituximab. All patients had progression-free survival and resolution of disease.

CONCLUSION

Based on the data obtained, current practice requires defined guidelines and centralised care.

Exome sequencing identifies recurrent BCOR alterations and the absence of KLF2, TNFAIP3 and MYD88 mutations in splenic diffuse red pulp small B-cell lymphoma

Splenic diffuse red pulp lymphoma is an indolent small B-cell lymphoma recognized as a provisional entity in the World Health Organization 2008 classification. Its precise relationship to other related splenic B-cell lymphomas with frequent leukemic involvement or other lymphoproliferative disorders remains undetermined. We performed whole-exome sequencing to explore the genetic landscape of ten cases of splenic diffuse red pulp lymphoma using paired tumor and normal samples. A selection of 109 somatic mutations was then evaluated in a cohort including 42 samples of splenic diffuse red pulp lymphoma and compared to those identified in 46 samples of splenic marginal zone lymphoma and eight samples of hairy-cell leukemia. Recurrent mutations or losses in BCOR (the gene encoding the BCL6 corepressor) – frameshift (n=3), nonsense (n=2), splicing site (n=1), and copy number loss (n=4) – were identified in 10/42 samples of splenic diffuse red pulp lymphoma (24%), whereas only one frameshift mutation was identified in 46 cases of splenic marginal zone lymphoma (2%). Inversely, KLF2, TNFAIP3 and MYD88, common mutations in splenic marginal zone lymphoma, were rare (one KLF2 mutant in 42 samples; 2%) or absent (TNFAIP3 and MYD88) in splenic diffuse red pulp lymphoma. These findings define an original genetic profile of splenic diffuse red pulp lymphoma and suggest that the mechanisms of pathogenesis of this lymphoma are distinct from those of splenic marginal zone lymphoma and hairy-cell leukemia.

An Epstein-Barr virus-positive classical Hodgkin lymphoma with exclusive sinusoidal growth pattern: An unusual morphologic variant

Classical Hodgkin lymphoma (cHL) typically involves lymph node parenchyma, and a case with Hodgkin cells confined within nodal sinusoids is extremely rare. Herein we report a case of cHL with a sinusoidal growth pattern. This 15-year old patient presented with B symptoms and was found to have bilateral cervical lymphadenopathy and an anterior mediastinal mass. Biopsy of a cervical lymph node demonstrated cohesive clusters of Reed-Sternberg (RS)-like cells suggestive of sinusoidal growth with an extrasinusoidal mixed inflammatory cell infiltrate characteristic of the microenvironment seen in cHL. The RS cells/variants were positive for CD30 and CD15, and showed down-regulation of B-cell program and CD45, an immunophenotypic profile consistent with cHL. The sinusoidal growth pattern was also highlighted by EBV staining. To the best of our knowledge, this is the first case of EBV-positive cHL that displays a sinusoidal growth pattern. The patient was treated with children's high risk cHL chemotherapy protocol and responded well.

Treatment of splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a distinct lymphoma entity characterized by an indolent clinical course and prolonged survival. Treatment is not standardized, since there are no prospective randomized trials in large series of SMZL patients. Splenectomy and rituximab represent the most effective treatment strategies used so far. The addition of chemotherapy to rituximab has not further improved the outcome, although this issue requires further investigation. Rituximab monotherapy has been associated with high response rates (∼90%), with approximately half of these responses being complete, even at the molecular level. More importantly, many of these responses are long-lasting, with a reported 7-year progression-free survival (PFS) at the rate of 69%. Maintenance rituximab treatment has been associated with further improvement of the quality of response as well as longer response duration in studies derived from one group of investigators. Based on its high efficacy and the good safety profile, rituximab represent one of the best treatment options for SMZL patients. Moreover, rituximab retains its efficacy in the relapse setting in most cases. Splenectomy is a meaningful alternative to rituximab in patients with bulky splenomegaly and cytopenias, without extensive bone marrow infiltration, who are fit for surgery. However splenectomy cannot completely eradicate the disease and it is also associated with greater morbidity or even mortality compared to rituximab. The choice of one of these two treatment approaches (rituximab or splenectomy) should mainly be based on patient's characteristics and on the disease burden. Novel agents are currently testing in low grade lymphomas including a small number of SMZL patients with promising results.

Splenic diffuse red pulp lymphoma has a distinct pattern of somatic mutations amongst B-cell malignancies

Splenic Diffuse Red Pulp Lymphoma (SDRPL) has been recently introduced as a provisional entity but differential diagnosis with other splenic lymphomas is needed to be clarified since the therapeutic approaches are distinct. Recently described recurrent mutations or CD180 expression appear useful for differential diagnosis. We completed our previous description in a larger cohort including 53 patients selected on the presence of characteristic villous cells in peripheral blood (PB) and a specific immunophenotype. Immunoglobulin heavy variable (IGHV), BRAF, MYD88, and NOTCH2 mutations were determined and CD180 and BRAF expressions were assessed. Most cases (79%) were IGHV mutated with an overrepresentation of IGHV3-23 (19%) and IGHV4-34 (21%). MYD88 L265P and NOTCH2 mutations were observed in one case each, whereas no BRAF V600E mutation or expression was found. All cases demonstrated a high CD180 expression. Those results strengthen the concept that SDRPL does emerge as a new lymphoma entity distinct from the other splenic lymphomas with circulating lymphocytes.

A Single-center Experience in Splenic Diffuse Red Pulp Lymphoma Diagnosis

The World Health Organization 2008 classification highlighted a new nosology-splenic diffuse red pulp lymphoma (SDRPL) with clinical and laboratory features similar to both splenic marginal zone lymphoma and hairy cell leukemia (HCL) and variant form of HCL. Experience of hematologists on the diagnosis and differential diagnosis of SDRPL is extremely limited. The aim of our report was to characterize the clinical and immunomorphologic features of SDRPL on our own observations. During 2013-2014, in National Research Center for Hematology, 87 spleen specimens removed from various B-cell lymphomas were analyzed. In four (4.6%) cases, the diagnosis SDRPL was made based on morphologic, immunohistochemical, immunophenotypic, molecular examination of spleen biopsies, blood and bone marrow samples. In all cases of SDRPL were observed significant splenomegaly, lymphocytosis from 56% to 94% (in two cases with leukocytosis 55.000 and 75.000 109/l). The circulating "villous" lymphocytes phenotype was CD20+ (bright), CD11c+/±, CD103 (weakly)+/±, LAIR-1+, CD25-, CD5-, CD10-, and CD23-. Mutation BRAFV600E was not detected. Bone marrow with minor lymphoid CD20+, CD25-, Annexin1-, Cyclin D1- cell infiltration. The average weight of the spleen was 3900 g (1450-9500 g), and morphologically, there was revealed lymphoid infiltration of red pulp with phenotype CD20+, DBA.44+, CD25-, Annexin1-, Cyclin D1-, CD103-, CD123-, CD27-, focal SD11c± and TRAP±. Now patients are observed in remission: two patients after splenectomy, two after splenectomy and cladribine+rituximab chemotherapy. SRDPL-a rare lymphoma that is suspected in the cases with significant splenomegaly and lymphocytosis with villous lymphocytes forms that have only a part of the classic markers HCL, with minor bone marrow infiltration. The standard diagnosis and treatment is splenectomy. Differential diagnosis of SMZL and HCL has clear criteria, but criteria of differentiation with variant HCL are still unknown.

Splenic marginal zone lymphoma: from genetics to management

Splenic marginal zone lymphoma (SMZL) is a rare B-cell malignancy involving the spleen, bone marrow, and frequently the blood. SMZL lymphomagenesis involves antigen and/or superantigen stimulation and molecular deregulation of genes (NOTCH2 and KLF2) involved in the physiological differentiation of spleen marginal zone B cells. Diagnosis requires either spleen histology or, alternatively, the documentation of a typical cell morphology and immunophenotype on blood cells coupled with the detection of intrasinusoidal infiltration by CD20+ cells in the bone marrow. Among B-cell tumors, deletion of 7q and NOTCH2 mutations are almost specific lesions of SMZL, thus representing promising diagnostic biomarkers of this lymphoma. Although the majority of SMZLs show an indolent course with a median survival of approximately 10 years, nearly 30% of patients experience a poor outcome. No randomized trials are reported for SMZL, and few prospective trials are available. A watch-and-wait approach is advisable for asymptomatic patients. Treatment options for symptomatic patients ranges from splenectomy to rituximab alone or combined with chemotherapy. In some geographic areas, a subset of patients with SMZL associates with hepatitis C virus infection, prompting virus eradication as an effective lymphoma treatment. It would be worthwhile to explore deregulated cellular programs of SMZL as therapeutic targets in the future; improved clinical and biological prognostication will be essential for identifying patients who may benefit from novel approaches.

[Experience in investigating splenic red pulp lymphoma]

AIM

To generalize hematologists' experience of the diagnosis and differential diagnosis of splenic red pulp lymphoma (SRPL).

MATERIAL AND METHODS

Eighty-seven splenic biopsy specimens taken from patients with different B-cell lymphoproliferative diseases were examined in the Hematology Research Center in 2013-2014. The diagnosis of SRPL was based on the morphological, immunohistochemical, immunophenotypic, and molecular examinations of the splenic biopsy specimens, blood and bone marrow (BM) tests in 4 (4.6%) cases.

RESULTS

There was significant splenomegaly in all SRPL cases, lymphocytosis in 56 to 94% (leukocytes, 55 and 75·109/l in 2 cases), circulation of hairy lymphocytes with the phenotypes CD20+ (markedly), CD11c+/±, CD103+/± (weakly), LAIR-1+, CD25-, CD5-, CD10-, and CD23-, which did not contain tartate-resistant acid phosphatase, without BRAFV600E mutation, BM with insignificant lymphoid infiltration of CD20+, CD25-, Annexin 1-, and Cyclin D1-. The weight of the spleen averaged 3900 g (1450-9500 g); its tissue exhibited lymphoid infiltration of the red pulp with the phenotypes CD20+, DBA.44+, CD25-, Annexin1-, Cyclin D1-, CD103-, CD123-, CD27-, focal СD11c±, and TRAP±. Four patients (2 after splenectomy (SE) and 2 after SE and chemotherapy with cladribine and rituximab) are being followed up in remission.

CONCLUSION

SRPL is a rare disease that should be presumed to be in significant splenomegaly and lymphocytosis with hairy lymphocytes, which have only some markers for classical hairy cell leukemia (HCL), in minor BM lesion. SE is the standard for diagnosis and treatment. The differential diagnosis of SRPL with HCL has clear criteria and that with HCL-v is undetected.

Role of blood and bone marrow examination in the diagnosis of mature lymphoid neoplasms in patients presenting with isolated splenomegaly

OBJECTIVES

Mature lymphoid neoplasms presenting with 'prominent splenomegaly without significant lymphadenopathy' are uncommon and pose unique diagnostic challenges as compared to those associated with lymphadenopathy. Their descriptions in the literature are largely limited to a few case series. We analyzed the spectrum of these lymphomas diagnosed by peripheral blood (PB) and/or bone marrow (BM) examination.

METHODS

Over a period of 6 years, 75 patients were diagnosed with a lymphoma from PB/BM who had presented with predominant splenomegaly. Their clinical and laboratory records including PB and BM morphology; immunophenotyping using multi-parametric flow-cytometry and immunohistochemistry were reviewed. Wherever indicated, an extended panel of immunohistochemistry (IHC) was performed on BM biopsies for accurate sub-classification.

RESULTS AND DISCUSSION

The commonest lymphomas were hairy cell leukemia (HCL) (32%) and splenic marginal zone lymphoma (SMZL) (24%). Others included diffuse large B cell lymphoma (8%), chronic lymphocytic leukemia/small lymphocytic lymphoma (8%), mantle cell lymphoma (2.7%), and follicular lymphoma (1.3%), all of which usually presents with lymphadenopathy. SMZL was the commonest lymphoma among females and those with massive splenomegaly and lymphocytosis; while HCL was commonest in patients with pancytopenia. SMZL commonly presented with lymphocytosis; however, 22% of them also presented with pancytopenia.

CONCLUSION

The high diagnostic efficacy of PB and BM examination using flow-cytometry and immunohistochemistry in confirming and sub-classifying splenic lymphomas suggests that a thorough hematological evaluation should always precede a diagnostic splenectomy. Immunohistochemistry remains the best modality to identify sparse or intra-sinusoidal infiltration on BM biopsy and is particularly useful in patients with fibrotic marrows and pancytopenia.

Diagnosis of Splenic B-Cell Lymphomas in the Bone Marrow: A Review of Histopathologic, Immunophenotypic, and Genetic Findings

Splenic B-cell lymphomas are a heterogeneous group of diseases comprising several entities that exhibit overlapping features. Diagnosis of these lymphomas has been reliant on the histopathologic examination of the spleen. However, with advances in diagnostic modalities and therapy, splenectomy is not commonly performed, and diagnosis and subclassification must be rendered based on the blood and bone marrow findings. In this brief review, we summarize the morphologic, immunophenotypic, and genetic findings of splenic B-cell lymphomas in the blood and bone marrow.

Bone marrow stroma CD40 expression correlates with inflammatory mast cell infiltration and disease progression in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a mature B-cell neoplasm characterized by rather indolent clinical course. However, nearly one third of patients experience a rapidly progressive disease with a dismal outcome. Despite the characterization of clone genetics and the recognition of deregulated immunologic stimulation in the pathogenesis of SMZL, little is known about microenvironment dynamics and their potential biological influence on disease outcome. Here we investigate the effect of stroma-intrinsic features on SMZL disease progression by focusing on the microenvironment of the bone marrow (BM), which represents an elective disease localization endorsing diagnostic and prognostic relevance. We show that the quality of the BM stromal meshwork of SMZL infiltrates correlates with time to progression. In particular, we describe the unfavorable prognostic influence of dense CD40 expression by BM stromal cells, which involves the contribution of CD40 ligand (CD40L)-expressing bystander mast cells infiltrating SMZL BM aggregates. The CD40/CD40L-assisted crosstalk between mesenchymal stromal cells and mast cells populating the SMZL microenvironment finds correlation in p53(-/-) mice developing SMZL and contributes to the engendering of detrimental proinflammatory conditions. Our study highlights a dynamic interaction, playing between nonneoplastic elements within the SMZL niche, toward disease progression.

Clonal B-cell lymphocytosis exhibiting immunophenotypic features consistent with a marginal-zone origin: is this a distinct entity?

Clonal B-cell lymphocytosis of potential marginal-zone origin (CBL-MZ) rarely progresses to a well-recognized lymphoma. CBL-MZ does not require treatment in the absence of progressive disease.

Bone marrow trephine biopsy involvement by lymphoma: review of histopathological features in 511 specimens and correlation with diagnostic biopsy, aspirate and peripheral blood findings

AIMS

This study aimed to evaluate the key features of bone marrow trephine (BMT) biopsy involvement by lymphoma.

METHODS

511 cases were assessed for percentage of marrow involvement, pattern of involvement (diffuse, nodular, paratrabecular, interstitial or intrasinusoidal), presence/absence of granulomas, stromal fibrosis and necrosis, presence/absence of neoplastic/reactive follicles and discordance with other biopsy sites. Correlation with aspirate and peripheral blood findings was made in a subset of 345 patients (167 aspirates, 178 blood).

RESULTS

The most frequent subtype was follicular lymphoma (26.2%) followed by extranodal marginal zone (23.1%), lymphoplasmacytic (19.2%), diffuse large B cell (DLBCL) (12.5%), Hodgkin (HL) (5.7%) and mantle cell lymphomas (4.3%). The predominant pattern in follicular lymphoma was paratrabecular. Marginal zone lymphomas of all types and lymphoplasmacytic lymphoma showed a relatively even distribution between diffuse, interstitial, paratrabecular and nodular patterns. The majority of mantle cell lymphoma cases showed either diffuse or nodular patterns. A diffuse pattern was common in DLBCL and Burkitt lymphomas. An intrasinusoidal pattern was seen only in extranodal and splenic marginal zone lymphomas. Granulomas and fibrosis were uncommon in small cell B cell lymphomas but frequent in DLBCL and HL. Aspirate and trephine results concurred in 73.8% of cases overall, but this varied widely between subtypes. Peripheral blood involvement rates by lymphoma also varied, with a mean of 37.1%.

CONCLUSIONS

Different lymphomas often demonstrate reliably characteristic architectural patterns of marrow involvement which can help differentiate them even when cytological features do not permit this, and marrow stromal and other background changes may also be useful pointers towards a particular lymphoma subtype.