Splenic Diffuse Red Pulp Small B-cell Lymphoma Research Articles

Splenic B Cell Lymphoma Innate Immune Cells: Detection of Red Versus White Pulp Lymphoma Differences in NK Cell Populations By High-Parameter Flow Cytometry

Introduction Splenic B-cell lymphomas, (SLs, total incidence ~1:100,000/year) comprise four distinct indolent B-cell non-Hodgkin lymphomas. Three predominantly involve the red pulp of the spleen (classical hairy cell leukemia (HCL), hairy cell leukemia variant (HCLv) and splenic diffuse red pulp small B-cell lymphoma (SDRPL)) and the fourth predominantly involves the white pulp (splenic marginal zone lymphoma (SMZL)). HCL is usually diagnosed by detection of an activation mutation in BRAF and responds well to treatment. We focused our study on the remaining three diseases, which have overlapping clinical presentations with only subtle differences in their morphology and phenotypes, but have considerable differences in prognosis, response to treatment and outcome. The white pulp lymphoma SMZL generally has good treatment responses and longer survival, whereas the red pulp SLs, HCLv and SDRPL are less responsive to treatments with shorter survival. Cells of the tumor microenvironment (TME) may have distinct characteristics between these three diseases. We hypothesized that TME innate immune cells from red pulp SLs (HCLv, and SDRPL) would be similar to each other and distinct from the white pulp SL, SMZL.In this study, we report that natural killer (NK) cells, which are important innate immune cells critical for immune surveillance, vary in proportions among red and white pulp SLs. Methods We studied splenectomy specimens from patients with SMZL (n=8), HCLv (n=8), SDRPL (n=7), and controls (healthy, post-trauma, n=8). Cryo-preserved bulk splenic suspension cell isolates from fresh (<4 hour) surgical specimens and intact formalin-fixed paraffin embedded (FFPE) tissue sections were used. Human specimen collection and usage was conducted with written informed consent after approval of the Institutional Research Subjects Review Board. FFPE tissue sections were studied by immunohistochemical (IHC) staining and splenic suspension cells were analyzed by high-parameter fluorescence flow cytometry using a Cytek Aurora spectral flow cytometer with a 25-color myeloid and a 28-color NK/B-cell panel. Results IHC characterization showed an extensive network of innate immune cells as reflected by CD163 + macrophages. Using high-parameter flow cytometry, we focused on innate immune cells in the non-B- non-T-cell (CD3 -CD19 -) population. The average proportions of this population were: NK cells 25-36%, monocyte/macrophages 20-34%, dendritic cells 5-11%, and granulocytes 2%. Among the patient groups, the median percentage of NK cells was greater for controls (34%) and SMZL (35%) as compared to red pulp lymphomas (HCLv (28%), SDRPL (24%)). Next, we examined NK subtypes: 1) cytotoxic NK cells (CD56 +CD16 +), 2) cytokine-secreting weakly cytotoxic NK cells (CD56 +CD16 -), and 3) undefined NK cells (CD56 -CD16 +) as a median percentage of total NK cells. The major subtype for control and SMZL was CD56 +CD16 - with values of 58 and 44%, respectively. This subtype comprises only 38%-40% of red pulp SLs. Proportionally the CD56 +CD16 + subtype was the largest for red pulp SLs at 52-57% as compared to 30% for control and 38% for SMZL. The remaining CD56 -CD16 + NK cell subtype was generally higher among red pulp SLs (HCLv (9%), SDRPL (12%)) as compared to control (6%) and SMZL (4%) patients. The increase in cytotoxic CD56 +CD16 + subtype among red pulp SLs was confirmed by measuring the percentage of granzymeB +perforin + cells among mature cytotoxic NK cells (CD56 +CD16 +/ CD57 +NKG2a -). SLs had higher proportions of this NK phenotype (78-86% compared to control 69%) and red pulp SLs had the most granzymeB +perforin + proportions with 82 and 86% for HCLv and SDRPL, respectively. Discussion In summary, spleens from patients with SMZL had similar percentages of total NK cells to controls, with lower percentages in red pulp SLs. All SLs had a higher percentage of cytotoxic NK cells than control, with the red pulp SLs having the most. These data suggest that monoclonal antibody treatments targeting SL antigen, such as anti-CD20, may be effective by activating cytotoxic NK cell to target lymphoma cells by antibody-dependent cellular cytotoxicity. Thus, uncovering the characteristics of the TME may aid the development of non-invasive diagnostic procedures and/or precision therapies.

Hairy Cell Leukemia with Severe Leukocytosis

Introduction Hairy cell leukemia (HCL) is a rare indolent mature B-cells neoplasm that typically manifests with pancytopenia and splenomegaly. Nevertheless, significant splenomegaly, high hairy cells count in the blood, elevated β 2 microglobulin, and increased LDH can predict resistance to purine analogs. The absence of BRAF V600E mutation in HCL is rare and is associated with poorer outcomes. Case Presentation A 68-year-old female patient presented with symptomatic massive splenomegaly, leukocytosis (89,000 /microliter), monocytopenia, and thrombocytopenia. β 2microgobulin level was 4.4 mcg/L. Lactate dehydrogenase was 521 U/L. Peripheral blood and bone marrow examinations revealed typical hairy cells morphology, and the cells were positive for CD19, CD20, CD103, CD25, CD11c, CD200 (dim), and surface-Kappa. CD38 was negative. BRAF V600E result was wild-type. IGHV was mutated (IGHV3-49). She received first-line therapy with a 5-day course of Cladribine (0.15 mg/kg/day) with initial resolution of leukocytosis, normalization of platelets, and a 50% reduction in spleen size. This was followed by consolidation with an 8-weekly course of Rituximab (375 mg/m 2). Soon after the 2 nd dose of Rituximab, leukocytosis recurred, and she was initiated on second-line therapy with Bendamustine (90 mg/m 2 on days 1 and 2) along with Rituximab (BR). She has not achieved any durable response following two cycles of BR. Unfortunately, she suffered a septic shock requiring admission to our intensive care unit. Upon routine mental status evaluation, brain MRI revealed innumerable supratentorial and infratentorial bilateral acute/subacute and old microhemorrhages (Figure 1). This prompted further evaluation of unexplained recurrent episodes of pulmonary hemorrhages while on mechanical ventilation that were found to be secondary to pulmonary end-arterial cavitating lesions suggestive of hairy cells infiltration (Figure 2 arrowheads). As she was clinically unstable, we attempted to control leukocytosis with corticosteroids, leukapheresis aggressively and started the patient on Ibrutinib, but she succumbed to her disease. Discussion Recently, the 5 th edition of the World Health Organization classification of hematolymphoid tumors highlighted the splenic B-cell lymphoma and leukemia family that encompasses hairy cell leukemia (HCL), splenic B-cell lymphoma/leukemia with prominent nucleoli (SBLPN), formerly known as hairy-cell leukemia variant, splenic diffuse red pulp small B-cell lymphoma (SDRPL) and splenic marginal zone lymphoma (SMZL). HCL is typically an indolent mature B-cell neoplasm with characteristic pathologic features that preferentially insinuate the bone marrow and the spleen causing impaired hematopoiesis and splenomegaly. Unlike other disorders within this group, HCL commonly harbors BRAF V600E somatic mutation in almost all cases. Rarely, patients with HCL can have extramedullary involvement by the malignant cells. Leukocytosis in HCL appears to increase the risk of developing extramedullary lesions that can present unique clinical challenges necessitating early and effective therapy. According to the literature, brain lesions in HCL were described in three other cases, and leukocytosis was a common denominator. Our patient with significant leukocytosis had brainand pulmonary lesions, and the latter was the cause of her demise due tounusually aggressive and refractory disease. Therefore, we hypothesize that leukocytosis in HCL can be “the tip of the iceberg”. The higher the leukocytosis, the higher the burden of extramedullary disease, as in our case, who had simultaneous lesions in the brain and lungs. Patients with HCL and leukocytosis may warrant initial diagnostic evaluation to ensure the absence of potentially sinister lesions, which can inform subsequent monitoring and management plans. Additionally, more novel therapies could be considered sooner in the treatment course to control the disease and these lesions. Finally, our patient did not harbor BRAF V600E mutation, which likely resulted in further worse outcomes and limited the usage of targeted therapies like BRAF inhibitors.

Indolent B-cell splenic lymphomas have T cells with an exhausted phenotype

Abstract T cell dysregulation has been observed in many tumors, but has not been well-characterized in rare B-cell splenic lymphomas. We began defining the T cell populations in the tumor microenvironments of four human indolent B cell splenic lymphomas: splenic marginal zone lymphoma (SMZL), hairy cell leukemia (HCL), hairy cell leukemia variant (HCLv), and splenic diffuse red pulp small B-cell lymphoma (SDRPL). After Institutional Research Subjects Review Board approval, we studied de-identified cryopreserved bulk splenic tumor suspension cell isolates from fresh (less than 4 h) splenectomy tissue and matched intact formalin-fixed paraffin embedded (FFPE) tissue sections from 17 splenic lymphoma patients and 4 trauma patients (controls). Initial immunohistochemical staining analysis of FFPE tissue sections suggests that the distribution of intratumoral T cells is markedly different among B cell splenic lymphomas. In HCL, residual T cell zones appear retained, albeit diminished, while HCLv and SDRPL have markedly reduced T cells throughout with non-distinct zonation, and SMZL has prominent peritumoral collections of T cells at the interface of the neoplastic white pulp. High-parameter (32-color) fluorescence spectral flow cytometry (Cytek Aurora) analysis suggests that splenic lymphomas exhibit CD4+ and CD8+ T cells with higher proportions of transitional memory, regulatory, and exhausted phenotypes than controls. T cell activation may be enhanced in HCLv. HCLv and SMZL may have decreased naïve T cells. Finally, splenic lymphomas had higher proportions of T cells with an exhausted phenotype compared to trauma samples. In summary, our data suggests T cells are dysregulated in B-cell splenic lymphomas. American Association of Immunologists, Hairy Cell Leukemia Foundation / Sass Foundation for Medical Research, and generous donations by Elizabeth Aaron.

Clinical features and prognosis of eight patients with splenic diffuse red pulp small B-cell lymphoma

Objective: To investigate the clinical characteristics, response, and prognosis of splenic diffuse red pulp small B-cell lymphoma (SDRPL) . Methods: Eight cases of SDRPL were diagnosed and treated at Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, between May 2017 and April 2022. Data on the clinical features, laboratory results, bone marrow and spleen biopsy results, response, and prognosis were collected and analyzed. Results: The median age at diagnosis was 54 (42-69) years. Splenomegaly and lymphocytosis were present in all cases, and PET/CT revealed normal to slightly elevated splenic FDG uptake. All cases were in stage Ⅳ, with spleen, peripheral blood, and bone marrow but no proximal lymph nodes involved. The cytoplasm of neoplastic villous cells was abundant, and splenic pathology showed that small homogenous lymphocytes permeated the splenic sinus and splenic cord, and the white pulp atrophied. Immunohistochemistry was not typical, and B-cell markers including CD19, CD20 and CD79α were positive. After a median follow up of 35.5 (4-60) months, 7 cases were alive after splenectomy with or without chemoimmunotherapy. The patient with CCND3 P284A and MYC S146L mutation developed to B-cell prolymphocytic leukemia (B-PLL) 1 month after splenectomy and died at 16 months of follow-up. Conclusion: A rare indolent B-cell lymphoma that primarily affects the elderly, SDRPL. Most patients achieved long-term survival, but the prognosis of patients who progress to B-PLL was poor.

Innate Immune Microenvironment of Indolent B Cell Splenic Lymphomas: Role in Diagnosis and Treatment

Indolent splenic B-cell lymphomas are rare diseases (incidence <1:100,000) that include splenic marginal zone lymphoma (SMZL), hairy cell leukemia (cHCL), hairy cell leukaemia variant (HCLv), and splenic diffuse red pulp small B-cell lymphoma (SDRPL). These splenic lymphomas can have overlapping clinical presentations with only subtle differences in their morphology and phenotypes. However, there are considerable differences in prognosis, response to treatment, and outcomes. Better understanding of the tumor microenvironment (TME) is essential to design expedient and accurate diagnostic methods and precision drug treatments for each type of splenic B-cell lymphoma. We hypothesized each splenic lymphoma would have a distinct TME with some overlap for the red pulp lymphomas (cHCL, HCLv, and SDRPL). Human specimen collection and usage was approved by the Institutional Research Subjects Review Board. We studied cryo-preserved bulk splenic tumor suspension cell isolates from fresh (<4 hour) splenectomy tissue and intact formalin-fixed paraffin embedded (FFPE) tissue sections from 17 splenic lymphoma patients and 4 trauma patients (controls). FFPE tissue sections were studied by immunohistochemical (IHC) staining and splenic suspension cells analyzed by high-parameter fluorescence flow cytometry with a 29-color myeloid panel using a Cytek Aurora spectral flow cytometer. Initial IHC characterization of the splenic TME illustrated a markedly different distribution of intratumoral T cells (CD3) and macrophages (Mθ) (CD163). In cHCL, residual T cell zones appear retained, albeit diminished, while HCLv and SDRPL have markedly reduced T cells throughout with non-distinct zonation, and SMZL has prominent peritumoral collections of T cells at the interface of the neoplastic white pulp. Tissue architecture, as evidenced by splenic macrophage distribution, was markedly different. cHCL and HCLv showed diffuse but distorted networks of interdigitating macrophages, while SDRPL retained a nearly normal sinusoidal distribution of abundant macrophages, and SMZL showed total exclusion of CD163-positive Mθ from areas of confluent neoplastic white pulp. Analysis of splenic suspension cells showed an average of 72% B cells in the lymphoma specimens, twice that of trauma spleens. T cells made up the greatest fraction of non-B cells (~63%) for both the diseased and control samples. We analyzed the non-T and non-B cells to examine the innate immune cells. Granulocytes comprised on average 4% with no difference between the splenic lymphomas or trauma (Fig.1A). Trauma spleen had 86% macrophage/monocytes (M/Mθ)s, with similar values for HCLv (80%) and cHCL (74%). The percentage of M/Mθ was lower in SDRPL (55%) and SMZL (48%). We then analyzed the percentage of M/Mθ subtypes. As shown in (Fig.1B), CD14+CD16- was the major subtype for trauma (58%) and HCLv (50%). Conversely for cHCL, CD14loCD16+ was predominant (60%) subtype. SDRPL and SMZL shared similar subtype profiles with equal proportions of CD14+CD16- and CD14loCD16+ (40%). We then measured the dendritic cells of the innate immune population. SDRPL (41%) and SMZL (48%) had higher percentages than trauma (12%), HCLv (16%), or cHCL (20%). Conventional dendritic cell 2 (cDC2) was the predominant subtype comprising 50-74% of the DCs. Average conventional dendritic cell 1 (cDC1) and plasmacytoid dendritic cells (pDCs) were 30% and 9%, respectively. pDC was lower in cHCL than the other lymphomas (1%). Our data show a similar M/Mθ component of the innate immune TME in the red pulp lymphoma SDRPL and white pulp lymphoma SMZL. SDRPL and SMZL also had higher proportions of dendritic cells compared to cHCL, HCLv, or trauma spleens. cDC2 was the predominant DC type in the spleen regardless of disease state. We are currently analyzing flow cytometry panels to access natural killer cell distribution and T cell functionality. We aim to better understand immune cell interactions in the TME and discover variations between the splenic B-cell lymphomas, resulting in improved diagnosis and therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Splenic Diffuse Red Pulp Small B-Cell Lymphoma Descriptors and Clinicopathologic Determinants of Clinical Outcomes: Analysis of a Pooled Database

Introduction: Splenic Diffuse Red Pulp Small B-Cell Lymphoma (SDRPL) is a rare clinical entity representing <1% of B-Cell Lymphomas. Previously identified as a variant of SMZL, the WHO has recognized it as a provisional entity since its 2008 classification updates. The diagnosis 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). It is characterized by diffuse involvement of the splenic red pulp by small monomorphic B-cells. Due to our limited understanding of this disease, we conducted this pooled database analysis of all cases of SDRPL to delineate key clinicopathological characteristics, prognostic indicators and treatment modalities that affect outcomes in this rare lymphoma subtype. Methods: In order to study the demographic characteristics, molecular and immunohistochemical signatures, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 80 cases. Kaplan-Meier survival curves were constructed. Cox proportional hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall (OS) and disease-free survival (DFS) survival. Results: A total of 80 patients with confirmed SDRPL were identified. The median age was 66.5 years, with a peak incidence between 69 and 70. There was a male preponderance with M:F ratio of 1.7. Splenomegaly, hepatomegaly (HM), lymphadenopathy (LN), constitutional symptoms (CS), ECOG0-1, and bone marrow (BM) involvement were present in 91%, 33%, 21%, 44%, 95%, and 95%, respectively. The median splenic weight was 2450g. While splenic red pulp was solely involved in 69% of the cases, 31% had mixed red and white pulp involvement. Three patients had active HBV, one had EBV, 4 had skin involvement, and 1 transformed into B-PLL. SDRPL Immunophenotype consisted of: TRAP(37%), Annexin A1(5%), CD5(14%), CD11c(63%), CD19(97%), CD20&22(100%), CD25(11%), CD27(60%), CD79(100%), CD103(26%), Bcl2(80%), CyclinD1(10%). CyclinD3(55%), and BRAF(16%). The median OS and DFS of the whole group were not reached (mean 138 mo) and 86mo, respectively. Age > 60 adversely impacted DFS (84mo vs. NR, p=0.03). The same trend was noted for age and OS. Compared to no treatment, splenectomy alone and the addition of combination chemotherapy were superior, with a median DFS of 36, 105, and 100 months respectively (p=0.06). HM, BM involvement, WBC>20K, absolute lymphocyte count>5K, and platelets<100K tended to adversely impact DFS, while only BM involvement and platelets<100K tended to impact OS adversely. CD25+ status was detrimental to DFS (36 vs. 105mo, p=0.049) whereas CD103+ status was advantageous to DFS (NR vs. 42mo, p=0.06). When chemotherapy was used, purine analogues tended to have better DFS and OS (76 vs. 26mo, p=0.09) compared to CHOP-like regimens. Neither DFS nor OS was impacted by sex, CS, LN, splenic weight, or splenic white pulp involvement. Conclusions: This study presents an updated clinicopathologic data from a pooled cohort of patients with SDRPL. It identifies the clinical, immunohistochemical, and treatment modalities that are major determinants of DFS and OS in this rare and distinct B-cell lymphoma entity.

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.

Clinicopathological analysis of splenic red pulp low-grade B-cell lymphoma.

Primary splenic low-grade B-cell lymphoma of the red pulp comprises hairy cell leukemia (HCL) and splenic B-cell lymphoma/leukemia, unclassifiable (SPLL-U). SPLL-U is a rare disease that includes subtypes of a hairy cell leukemia-variant (HCL-v), splenic diffuse red pulp small B-cell lymphoma (SDRPL) and other types that are known as narrow sense SPLL-U (SPLL-U-NS). Notably, limited information is available regarding the BRAF mutation (V600E) and cyclin D3 expression in subtypes of SPLL-U. Therefore, we performed a pathological analysis of the BRAF mutation (V600E) and characterized pathological features of SPLL-U. We reviewed the pathological findings of 12 SPLL-U cases. The 12 cases considered included two cases of HCL-v, six cases of SPLL-U-NS and four undetermined cases. The BRAF mutation (V600E) was detected in three cases, which were all SPLL-U-NS. Cases with the BRAF mutation (V600E) have increased levels of CD103 expression and decreased cyclin D3 and cyclin D1 expression compared with cases that lacked the BRAF mutation. These findings suggest that the BRAF mutation might play a significant role in SPLL-U. Therefore, the significance of the BRAF mutation should be evaluated via genomic or transcriptional analyses of a large cohort of SPLL-U patients.

Clinicopathological features of splenic tumours of lymphoid tissue

BackgroundTo study the effects of splenectomy on treatment and diagnosis of tumours of lymphoid tissue of the spleen. MethodsFifty-three cases were reviewed from Peking University People’s Hospital from 2002 to 2017. According to WHO classification of tumours of haematopoietic and lymphoid tissues (2008) and classification updated (2016), the cases were studied by microscopy, immunohistochemistry and in situ hybridization, combined with the bone marrow biopsy and clinical examination. ResultsIn 53 cases, the male to female ratio was 3.4:1, the mean age was 55.4 years old, the median survival time was 17.0 months, and all patients present with variable degree of splenomegaly. The elevated percentage of lymphocyte in peripheral blood can be seen in 22 cases, and elevated LDH level in 24 cases. Abnormal blood counts can be seen in 26 cases before operation, and 22 cases remission to normal level partly or completely after operation. The clinical symptoms included abdominal pain or distension, fatigue, fever, and weight loss, etc. Seventeen cases present with lymphoadenopathy of abdomen or other sites. Fourteen cases were stage I or II, whereas 6 were stage III, 28 were stage IV. Forty-three cases were splenic B-cell marginal zone lymphoma (SMZL)(48.8%,21/43), DLBCL(23.3%,10/43), splenic diffuse red pulp small B-cell lymphoma (SDRPSBL)(11.6%,5/43), mantle cell lymphoma (MCL)(9.3%,4/43), follicular lymphoma (FL)(4.7%,2/43), composite lymphoma (CL, DLBCL and classical Hodgkin lymphoma)(2.3%,1/43) in turn, and the remaining 10 cases were chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) (n = 4), hairy cell leukaemia (HCL) (n = 1), hepatosplenic T-cell lymphoma (HSTL) (n = 5). The survival period of SMZL and DLBCL was 25.7, 18.6 months, respectively. Thirteen cases were dead (27.1%, 13/48). The chemotherapy protocol included Hyper-CVAD A/B with/without R (Rituximab), COP, CHOP with/without R etc. The prognosis of those with elevated LDH level, high clinical staging, B symptom, and older than 60 year old was obviously worse, and the prognosis of DLBCL was worse than that of SMZL. ConclusionsMost splenic lymphoid tumors present with splenomegaly and abnormal blood counts, and complete or part remission of blood counts can be seen after splenectomy, and splenectomy is also helpful for pathological diagnosis. The most common pathological types are SMZL and DLBCL. The definite diagnosis can be made by combining with clinical features, histopathology, immunophenotype, genetics, bone marrow biopsy and laboratory examination.

NOTCH1, TP53, and MAP2K1 Mutations in Splenic Diffuse Red Pulp Small B-cell Lymphoma Are Associated With Progressive Disease.

Splenic diffuse red pulp small B-cell lymphoma (SDRPL) is considered an indolent neoplasm and its pathogenesis is not well known. We investigated the molecular characteristics of 19 SDRPL patients, 5 of them with progressive disease. IGHV genes were mutated in 9/13 (69%). Cytogenetic and molecular studies identified complex karyotypes in 2 cases, and IGH rearrangements in 3, with PAX5 and potentially TCL1 as partners in each one of them. Copy number arrays showed aberrations in 69% of the tumors, including recurrent losses of 10q23, 14q31-q32, and 17p13 in 3, and 9p21 in 2 cases. Deletion of 7q31.3-q32.3 was present in only 1 case and no trisomies 3 or 18 were detected. NOTCH1 and MAP2K1 were mutated in 2 cases each, whereas BRAF, TP53, and SF3B1 were mutated each in single cases. No mutations were found in NOTCH2 or MYD88. Four of the 5 patients with aggressive disease had mutations in NOTCH1 (2 cases), TP53 (1 case), and MAP2K1 (1 case). The progression-free survival of patients with mutated genes was significantly shorter than in the unmutated (P=0.011). These findings show that SDRPL share some mutated genes but not chromosomal alterations, with other splenic lymphomas, that may confer a more aggressive behavior.

Pathomorphological Diagnosis of Splenic Diffuse Red Pulp Small B-Cell Lymphoma

Background. Unclassifiable splenic B-cell lymphoma/leukemia is a rare and poorly studied disorder introduced in the WHO classification of hematopoietic and lymphoid tissue malignancies for the first time in 2008. This type of lymphoma requires differential diagnosing between hairy cell leukemia-variant (HCL-V) and splenic diffuse red pulp small B-cell lymphoma (SDRPL). Aim. To develop criteria for diagnosis of SDRPL by comparison of bone marrow biopsies (BMB) and surgical specimens of the spleen. Methods. In the Department of Morbid Anatomy of the Hematology Research Center, preoperative BMBs and surgical specimens of the spleen (2013-2015) were compared in 71 patients (men/women ratio 1:2.6, age range 44-81, median age 58 years) using morphological and extended immunohistochemical studies. Sanger sequencing and PCR assay were carried out to analyze the mutational status of IgHV and to identify mutations in MAP2K1, NOTCH, BRAF. Results. SDRPL was diagnosed in 5 (7 %) of 71 patients. In 2 groups of patients (with normal and high WBC count), the morphological features of spleen tissue were similar to those of a neoplastic substrate of HCL-V. The immunohistochemical assay demonstrates monomorphic expression of CD20 and DBA.44 and heterogeneous expression of CD11c, TRAP, CD103, CD123 in all cases. In none of the 5 cases, expression of CD25, CD27, Cyclin D1, Annexin-1 was found. In bone marrow (unlike HCL and HCL-V), predominantly interstitial and intravascular scant CD20+ lymphoid infiltration (4 of 5 cases) was found without detectable nucleoli in nuclei of small lymphoid cells. In 1 case, there was a combined lymphoid infiltration: CD20+ microfocalinterstitial infiltration with an intravascular component. No persistent molecular mutations in the spleen tissue specimens were found. Conclusion. SDRPL is diagnosed in 7 % of splenic B-cell lymphomas. It is a rare disorder, whose verification requires an integrated approach taking into account clini cal and laboratory data, results of flow cytometry, cytological, morphological, extended IHC and molecular biological studies.

Chronic B-cell lymphoproliferative disorders with hairy cells

The standardized blood smear examination is the first step in the diagnosis of a B-cell chronic lymphoproliferative disorder and can guide further investigations. In the laboratory, the identification of hairy cells on blood smear is a matter of daily practice. Hairy cell proliferations represent heterogeneous entities and their respective diagnoses can be difficult. If hairy cell leukemia (HCL) and splenic marginal zone lymphoma (SMZL) represent separate entities, the variant form of HCL (HCLv) and splenic diffuse red pulp small B-cell lymphoma (SDRPL) remain provisional entities in the 2008 WHO classification. We discuss the main clinical and biological characteristics of these four entities and appropriate means to characterize, identify and distinguish from each other; standardized blood smear examination, multiparameter flow cytometry analysis, analysis of the repertoire of immunoglobulins heavy chains genes and their mutational status (mutated or unmutated profile), molecular analyses: BRAF gene V600E mutation in HCL and MAP2K1 gene mutations in HCLv. We also discuss the main therapeutic aspects with emphasis on the new targeted drugs that enter into force in the therapeutic arsenal.

A comprehensive immunophenotypic marker analysis of hairy cell leukemia in paraffin-embedded bone marrow trephine biopsies--a tissue microarray study.

Hairy cell leukemia (HCL) is an uncommon B cell lymphoproliferation characterized by a unique immunophenotype. Due to low number of circulating neoplastic cells and 'dry tap' aspiration, the diagnosis is often based on BM trephine biopsy. We have performed a consecutive immunohistochemical analysis to evaluate diagnostic usefulness of various HCL markers (CD11c, CD25, CD68, CD103, CD123, CD200, annexin A1, cyclin D1, DBA.44, HBME-1, phospho-ERK1/2, TRAP, and T-bet) currently available against fixation resistant epitopes. We analyzed tissue microarrays consisting of samples gained from 73 small B-cell lymphoma cases, including hairy cell leukemia (HCL) (n = 32), HCL variant (HCL-v) (n = 4), B-cell chronic lymphocytic leukemia (B-CLL) (n = 11), lymphoplasmacytic lymphoma (LPL) (n = 3), mantle cell lymphoma (MCL) (n = 10), splenic diffuse red pulp small B cell lymphoma (SDRPL) (n = 2), splenic B cell marginal zone lymphoma (SMZL) (n = 8), and splenic B cell lymphoma/leukemia, unclassifiable (SBCL) (n = 3) cases. The HCL cases were 100% positive for all but 2 (DBA.44 and CD123) of these markers. Annexin A1 showed 100% specificity and accuracy, which was followed by CD123, pERK, CD103, HBME-1, CD11c, CD25, CD68, cyclin D1, CD200, T-bet, DBA.44, and TRAP, in decreasing order. In conclusion, our results reassured the high specificity of annexin A1 and pERK, as well as the diagnostic value of standard HCL markers of CD11c, CD25, CD103, and CD123 also in paraffin-embedded BM samples. Additional markers, including HBME-1, cyclin D1, CD200, and T-bet also represent valuable tools in the differential diagnosis of HCL and its mimics.

Monoclonal antibody HBME-1 reacts with a minor subset of B cells with villous surface and can be useful in the diagnosis of hairy cell leukemia and other indolent lymphoproliferations of villous B lymphocytes

The Hector Battifora mesothelial epitope-1 (HBME-1) monoclonal antibody has been generated against human mesothelioma cells and recognizes a biochemically unknown membrane epitope. We have accidentally found that the HBME-1 reacts with scattered lymphocytes showing villous surface in hyperplastic lymphoid tissue. To evaluate its reactivity pattern, we have performed a consecutive immunohistochemical study in nonneoplastic bone marrow and lymphoid samples (n = 40), as well as in malignant lymphoproliferations (n = 427), including hairy cell leukemia (HCL) (n = 72), HCL variant (HCL-v) (n = 13), splenic diffuse red pulp small B cell lymphoma (SDRPL) (n = 8), splenic B cell marginal zone lymphoma (SMZL) (n = 59), and splenic B cell lymphoma/leukemia, not further classifiable on bone marrow morphology (SBCL) (n = 37) cases. The staining pattern of HBME-1 was compared to DBA.44. HBME-1(+) villous lymphocytes were constantly detected in low number in nonneoplastic lymphoid tissues. With multicolor immunofluorescence staining, HBME-1(+) lymphocytes showed a CD20(+)/CD79a(+)/IgM(+) B cell phenotype. In B cell lymphoproliferations of villous lymphocytes, HBME-1 reactivity was demonstrated in 96 % of HCL, 39 % of HCL-v, 50 % of SDRPL, 12 % of SMZL, and 19 % of SBCL cases. Nodal and extranodal marginal zone lymphoma cases were positive in 12 % of the cases. A small minority (4 %) of the other B cell lymphomas and no T cell lymphoma revealed tumor cell reactivity with HBME-1. In conclusion, our study has established that HBME-1 reacts with a minor subset of B lymphocytes and a small proportion of B cell lymphomas, which has not been described previously. We suggest that HBME-1 can be a useful marker in the diagnosis of HCL and other indolent lymphoproliferations of villous B lymphocytes.

Nouveautés sur les hémopathies lymphoïdes chroniques B matures

Summary Chronic lymphocytic leukemia (CLL) is the most common adult lymphoid malignant disease in western countries, with 3800 new incident cases in France in 2011 (1% of all cancers). The criteria for CLL diagnosis recently changed. The diagnosis is based on the combination of lymphocyte morphology, the presence of more than 5 × 109/L circulating clonal B-cells persisting for more than 3 months and a characteristic immunophenotype. In routine, it is recommended to explore patients with lymphocytosis more than 4 × 109/L. Monoclonal B-cells lymphocytosis (MBL) is defined by the presence of less than 5 × 109/L circulating B-cells. MBL is a step before CLL and can progress to CLL. The diagnosis of B-cell chronic lymphoproliferative disorders with hairy cells in the peripheral blood is a clinical challenge. Hairy cell leukemia (HCL) and splenic marginal zone lymphoma (SMZL) with villous lymphocytes in the peripheral blood are well-defined clinical entities. Inversely, splenic diffuse red pulp small B-cell lymphoma (SRPL) and hairy cell leukemia variant (HCL-v) are provisional entities in the WHO 2008 classification. We will discuss the characteristics of each entity and the ways we can use for distinguishing them: morphology, cytometry and molecular studies.

Bone Marrow Histopathology in the Diagnostic Evaluation of Splenic Marginal-zone and Splenic Diffuse Red Pulp Small B-cell Lymphoma

Primary splenic small B-cell lymphomas mostly comprise the distinct entity of splenic marginal-zone lymphoma (SMZL) and the provisional category of splenic lymphoma/leukemia unclassifiable, mainly represented by the hairy cell leukemia variant and splenic diffuse red pulp small B-cell lymphoma (SDRL). Until recently, histopathologic examination of splenectomy specimens was considered mandatory for the diagnosis of SMZL. However, nowadays, mainly because of advances in chemoimmunotherapy, splenectomy is performed much less frequently. We evaluated the diagnostic efficacy of bone marrow biopsy (BMB) histopathology in the diagnostic approach toward SMZL and SDRL and tested whether it may serve as a substitute for spleen histopathology in the differential diagnosis between these 2 entities. To this end, we conducted a paired assessment of BMB and spleen diagnostic samples from 46 cases with a diagnosis of SMZL (n=32) or SDRL (n=14) based on spleen histopathology. We demonstrate that detailed immunohistopathologic BMB evaluation offers adequate evidence for the confirmation of these entities and their differential diagnosis from other small B-cell lymphoma histotypes. Notably, the immunophenotypical profile of SMZL and SDRL was identical in both BMB and spleen specimens for 21 evaluated markers. Paired assessment of BMB and spleen specimens did not identify discriminating patterns of BMB infiltration, cytology, and/or immunohistology between SMZL and SDRL. Accordingly, bone marrow histopathology contributes significantly in confirming the diagnosis of SMZL and SDRL. However, presently it is not possible to distinguish SMZL from SDRL on the basis of BMB evaluation alone; hence, histopathologic examination of the spleen remains the "gold standard" approach.

Grey zone lymphoid neoplasms with features overlapping between splenic marginal zone lymphoma and hairy cell leukaemia: splenic B-cell lymphoma/leukaemia, unclassifiable

The best characterized primary splenic B-cell lymphoma/leukaemias include splenic marginal zone lymphoma (SMZL) and hairy cell leukaemia (HCL). However, there are other primary splenic B-cell neoplasms that do not have the characteristic features of SMZL or HCL. The WHO classification has proposed a provision entity—splenic B-cell lymphoma/leukaemia, unclassifiable (SBLLu) to include the better-defined small B-cell clonal lymphoproliferations involving spleen that do not fall into any of the other types of B-cell lymphoid neoplasms. The recognized provisional entities among SBLLu include splenic diffuse red pulp small B-cell lymphoma (SDRPSBL) and hairy cell leukaemia variant (HCLv). The possibility of SBLLu arises when the spleen shows diffuse red pulp involvement, or when the bone marrow trephine biopsy shows extensive intra-sinusoidal involvement by a small B-cell lymphoma with marked splenomegaly, or when a patient with marked splenomegaly presents with a high white cell count in the peripheral blood without monocytopenia, and with presence of atypical lymphocytes with villous or hairy projections and with prominent nucleoli, and the cells are CD25 negative. These clonal B cells lack IgD and frequently express IgG with or without IgM. They are consistently negative for CD25, Annexin A1, cyclin D1, CD38 and cytoplasmic Ig, and are variably positive for CD76, tartrate-resistant acid phosphatase, CD11c, CD103 and CD123. Distinguishing SDRPSBL and HCLv can pose diagnostic problems. Features favouring SDRPSBL include relatively low lymphocytosis along with leucopenia and thrombocytopenia, lack of a paraprotein and a relatively monomorphic cytology with only a proportion of cells being nucleolated. Features that favour HCLv include high white cell count (average ∼35 × 109/L) and presence of monocytes, prominent and obvious intra-sinusoidal infiltrates in spleen and bone marrow and prominence of cells with nucleoli resembling prolymphocytes.

Relevance of a scoring system including CD11c expression in the identification of splenic diffuse red pulp small B‐cell lymphoma (SRPL)

'Splenic red pulp lymphoma with numerous basophilic villous lymphocytes' (SRPL), recently described, is characterized by clinical, morphologic, immunologic, cytogenetic and molecular features distinct from SMZL/SLVL and HCL. In particular, the intensity of CD11c staining (expressed as fluorescence intensity -RFI-) in SRPL is significantly different from the RFI in SMZL/SLVL and HCL. Moreover the use of a scoring system based on the expression of CD11c, CD22, CD76, CD38 and CD27 appears to improve the differential diagnosis between SRPL and SMZL/SLVL and emphasizes that SRPL is an entity closed to but distinct from SMZL/SLVL.

Gene Expression Profiling Classifies Splenic Marginal Zone Lymphoma and Hairy Cell Leukemia-Variant as Related Diseases That Are Distinct From Typical Hairy Cell Leukemia.

Abstract 3467Poster Board III-355Hairy cell leukemia (HCL) is an uncommon B-cell malignancy that shares some features with a variant form, HCL-variant, and splenic marginal zone lymphoma (SMZL). The distinction between these disorders can be difficult, but correct diagnosis is important for patient management and clinical outcome. The recent WHO classification has recognized SMZL as a distinct entity and HCL-variant was included in a provisional category of unclassifiable splenic lymphomas involving the splenic red pulp that also includes splenic diffuse red pulp small B-cell lymphoma (SDSL). The molecular features of these disorders are still largely uncharacterized and genomic studies have been limited due to their rarity. We have used Affymetrix gene expression microarrays to compare the transcription profiles of 31 HCL, 24 HCL-variant, 44 SMZL and 5 cases of SDSL with the aim of elucidating the relationships between these disorders and to identify novel potential therapeutic and disease-specific diagnostic targets. Total RNA was extracted from PBMC samples enriched for tumor cells (median 89%, range 70-98%) and the expression of approximately 18,000 genes was interrogated using the Affymetrix Human Exon 1.0 ST Array. Data were normalized and analyzed using Partek Genomics Suite® and differentially expressed transcripts between the disorders were identified by ANOVA. Unsupervised hierarchical clustering revealed disease-related patterns within the transcription profiles. Strikingly, the HCL-variant, SMZL and SDSL profiles clustered together and separately from those of typical HCL. Using a false discovery rate threshold of <0.001 and an expression fold-change >2 we identified 366 transcripts that distinguished HCL from HCL-variant, SMZL and SDSL. Using these same criteria, and even those less stringent, we could not identify a gene expression signature that could distinguish between HCL-variant, SMZL and SDSL. Biological interpretation of the data revealed many of the differentially expressed transcripts linked to immune response and signal transduction processes, including key oncogenes and tumor suppressor genes. Transcripts with higher expression in HCL-variant, SMZL and SDSL relative to HCL were associated with lymphocyte activation and proliferation, NFκB signaling and integrin signaling. Conversely, transcripts with higher expression in HCL relative to HCL-variant, SMZL and SDSL, comprised amongst others, pathways of antigen processing, MAP kinase signaling, JAK-STAT signaling, and FLT3 signaling. Comparison of the transcription signatures of HCL, HCL-variant and SMZL provides insight into their relationships and for the first time provides strong evidence that HCL-variant and SDSL may be variant forms of SMZL and that HCL remains as a distinct disease entity characterized by different signaling pathways. These data further strengthen our previous observation that showed that the immunoglobulin heavy chain gene (IGH) repertoire of HCL-variant is more similar to SMZL than to HCL and that, in contrast to HCL, both HCL-variant and SMZL contain subsets of cases with unmutated IGHV. Interestingly, the expression profiles of both HCL-variant and SMZL could not be discriminated based on their IGHV mutation status. We are currently performing further analyses of these data, including comparison with the expression profiles of normal B cells, with the aim of gaining further insight into the clonal history and the normal B-cell counterpart of these disorders. DisclosuresNo relevant conflicts of interest to declare.