Benign, atypical and malignant lymphoproliferative disorders in rheumatoid arthritis patients

CD30 influences germinal center B-cell dynamics and the expansion of IgG1-switched B cells

Initially, identified as a Hodgkin lymphoma marker, CD30 was subsequently detected on a subset of human B cells within and around germinal centers (GCs). While CD30 expression is typically restricted to a few B cells, expansion of CD30-expressing B cells occurs in certain immune disorders and during viral infections. The role of CD30 in B cells remains largely unclear. To address this gap in knowledge, we established a conditional CD30-knockin mouse strain. In these mice, B-cell-specific CD30 expression led to a normal B-cell phenotype in young mice, but most aged mice exhibited significant expansion of B cells, T cells and myeloid cells and increased percentages of GC B cells and IgG1-switched cells. This may be driven by the expansion of CD4+ senescence-associated T cells and T follicular helper cells, which partially express CD30-L (CD153) and may stimulate CD30-expressing B cells. Inducing CD30 expression in antigen-activated B cells accelerates the GC reaction and augments plasma cell differentiation, possibly through the posttranscriptional upregulation of CXCR4. Furthermore, CD30 expression in GC B cells promoted the expansion of IgG1-switched cells, which displayed either a GC or memory-like B-cell phenotype, with abnormally high IgG1 levels compared with those in controls. These findings shed light on the role of CD30 signaling in GC B cells and suggest that elevated CD30+ B-cell numbers lead to pathological lymphocyte activation and proliferation.

Diagnostic challenges in patients with Castleman disease, a single center experience from Hungary

Castleman disease is a rare and atypical lymphoproliferative disorder characterized by diverse clinical manifestations. It has both unicentric and multicentric forms, the latter with further subdivisions, i.e., human herpesvirus 8-associated and idiopathic forms. The diagnosis of Castleman disease is often delayed, as it is rare, and because it shares clinical features with different autoimmune, inflammatory, and malignant lymphoproliferative disorders. The first-line treatment in unicentric form is mainly surgical, while in idiopathic Castleman disease, anti-interleukin-6 treatment is the therapy of choice. In virus-associated diseases, antiretroviral therapy and rituximab are recommended. In Hungary, only a few cases of Castleman disease have been published. This report presents our two decades of experience in the challenging diagnosis and management of this rare disorder, most properly underdiagnosed in Hungary. We provide insights into seven unicentric and five idiopathic multicentric Castleman disease cases, the latter ones especially highlighting the diagnostic and therapeutic challenges due to the variable and unique clinical features both of patients and diseases, e.g., bronchiolitis obliterans, stage IV diabetic renal failure, anti-HBc positivity, siltuximab treatment period, respectively.

Immune deficiency/dysregulation -associated lymphoproliferative disorders. Revised classification and management

Significant advances in the field of lymphoma have resulted in two recent classification proposals, the International Consensus Classification (ICC) and the 5th edition WHO. A few entities are categorized differently in the ICC compared to the WHO. Nowhere is this more apparent than the immunodeficiency lymphoproliferative disorders. The three previous versions of the WHO classification (3rd, 4th and revised 4th editions) and the ICC focused on four clinical settings in which these lesions arise for primary categorization. In contrast the 2023 WHO 5th edition includes pathologic characteristics including morphology and viral status, in addition to clinical setting, as important information for lesion classification. In addition, the 2023 WHO recognizes a broader number of clinical scenarios in which these lesions arise, including not only traditional types of immune deficiency but also immune dysregulation. With this classification it is hoped that new treatment strategies will be developed leading to better patient outcomes.

Atypical lymphoplasmacytic and immunoblastic proliferation: A Systematic Review

Atypical lymphoplasmacytic and immunoblastic proliferation (ALPIBP) was first reported in 1984 as characteristic histological findings in lymph nodes associated with autoimmune diseases, but it has not been clearly defined to date. To summarize the histological characteristics and clinical diagnoses associated with ALPIBP, we searched MEDLINE and EMBASE for all peer-reviewed articles using keywords including "atypical lymphoplasmacytic and immunoblastic lymphadenopathy" from their inception to December 27, 2023. We also summarized the courses of three cases with a pathological diagnosis of ALPIBP. Nine articles with 52 cases were included. Among the total of 55 cases, including the three from our institution, the median age of the cases was 63.5 years with a female predominance (69.5%). Lymphadenopathy was generalized in 65.6% and regional in 34.4% of cases. RA (24.4%), SLE (24.4%), and autoimmune hemolytic anemia (20.0%), were common clinical diagnoses. A combination of cytotoxic chemotherapy was used in 15.6% of cases due to the suspicion of malignancy. Nodal T-follicular helper cell lymphoma, angioimmunoblastic type, methotrexate-associated lymphoproliferative disorders, and IgG4-related diseases were listed as important diseases that need to be pathologically differentiated from ALPIBP. This review summarizes the current understanding of the characteristics of ALPIBP. Given that underrecognition of ALPIBP could lead to overdiagnosis of hematological malignancy and unnecessary treatment, increased awareness of the condition in pathologists and clinicians is crucial.

Intraperitoneal hyaline vascular Castleman disease: Three case reports

BACKGROUND

Castleman disease (CD) was first reported in 1954. It is a rare non-malignant lymphoproliferative disease with unclear etiology. As the clinical manifestations of CD are different, there are difficulties in its diagnosis and treatment. Therefore, for patients with CD, it is important to establish the diagnosis in order to choose the appropriate treatment.

CASE SUMMARY

In this report, three patients with intraperitoneal CD treated at our center from January 2018 to June 2023 were reviewed, and the clinical and paraclinical examinations, diagnosis, and treatment were analyzed, and all three patients were diagnosed with CD by routine histopathological and immunohistochemical examinations.

CONCLUSION

CD is a complex and rare disease. Because there are no special clinical symptoms and laboratory abnormalities, the diagnosis often depends on routine pathological and immunohistochemical findings.

Clinical features and treatment outcomes of Castleman disease in children: a retrospective cohort in China

Castleman disease (CD) is a rare lymphoproliferative disorder of undetermined etiology. Unicentric CD (UCD) and multicentric CD (MCD) are two phenotypes of CD diagnosed by the histopathology of lymph nodes. We attempted to describe a pediatric CD cohort to optimize the management of this disease. We reviewed the medical records of pediatric patients diagnosed with CD between April, 2004, and October, 2022, at the Children's Hospital of Fudan University. Prognosis information was collected in January, 2023, by telephone inquiry. Twenty-two patients with UCD and 2 patients with MCD were identified, all with hyaline vascular (HV) type. The median ages at diagnosis were 10.75 years (IQR 8, 12.81) for UCD and 14.42 years (IQR 13.42, 15.42) for MCD. The most common lesion location of UCD was the neck (9/22, 40.91%) and abdomen (9/22, 40.91%). Systematic symptoms occurred on 10/22 (45.45%) patients with UCD and 1/2 (50%) patients with MCD, and abnormal laboratory indexes were detected in both. Resection and biopsy were performed on all patients. One out of two patients with MCD also received rituximab for upfront therapy. After a median of 4 years (IQR 1.5, 6) of follow-up time, the overall survival was 100% and the complete remission rate in UCD was 63%. There was no relapse or progression.

CONCLUSIONS

Our series demonstrated that HV-UCD was the most common type in children. Resection and biopsy were used for both deterministic diagnoses and treatments. Despite the high possibility to develop systematic inflammation, children with CD showed promising outcomes.

WHAT IS KNOWN

• Castleman disease is a rare lymphoproliferative disorder with limited cohort studies, especially in pediatrics. • The ubiquity of delayed confirmations and misdiagnoses points to a lack of knowledge about etiology and characteristics, which is a prerequisite for novel therapeutics.

WHAT IS NEW

• We retrospectively reviewed and analyzed the clinical and pathological symptoms, laboratory and imaging features, and treatment outcomes of a Chinese pediatric cohort with Castleman disease. • Our work may improve the recognition and optimize the management of this rare disease in children.

Expression of IDO1 and PD-L2 in Patients with Benign Lymphadenopathies and Association with Autoimmune Diseases

The expression patterns of IDO1 and PD-L2 have not been thoroughly investigated in benign lymphadenopathies. The aim with this study was to elucidate how IDO1 and PD-L2 are expressed in benign lymphadenopathies in patients with autoimmune diseases (AD) compared to patients without AD. Formalin-fixed paraffin-embedded lymph nodes from 22 patients with AD and 57 patients without AD were immunohistochemically stained to detect IDO1 and PD-L2. The material was previously stained with EBER in situ hybridization to detect cells harboring the Epstein-Barr virus (EBV). IDO1 and PD-L2 were generally expressed by leukocytes to low degrees, while follicular IDO1+ cells were very rare. IDO1+ cells in single germinal centers were detected in five patients, and there was a high co-occurrence of follicular EBV+ cells in these cases (three of five patients). There were also significant correlations between interfollicular EBV+ cells and interfollicular IDO1+ cells (Spearman rho = 0.32, p = 0.004) and follicular IDO1+ cells (Spearman rho = 0.34, p = 0.004). High or low amounts of IDO1+ or PD-L2+ cells were not statistically significantly associated with patients with AD. However, the lymphadenopathy with the highest amount of interfollicular IDO1+ cells, which was also the only lymphadenopathy in which endothelial cells expressed IDO1, was in a patient with sarcoidosis. This study further supports that the EBV induces the expression of IDO1 and our findings should be recognized by future studies on IDO1 and PD-L2 in inflammatory and malignant conditions.

Castleman disease and mimickers: Clinicopathological findings of atypical lymphoproliferative disorders associated with autoimmune disease

Atypical lymphoproliferative disorders (LPDs) related with autoimmune disease (AID) show marked clinicopathological diversity, which are defined as three distinct clinicopathological subtypes such as those resembling Castleman disease (CD), atypical paracortical hyperplasia with lymphoid follicles (APHLF), and atypical lymphoplasmacytic and immunoblastic proliferation (ALPIB). We studied excisional biopsy specimens from 31 patients with atypical LPDs associated with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren syndrome (SjS). The lesions in these 31 cases were classified into 6 (19.4%) cases resembling CD, 14 (45.2%) cases of APHLF, and 11 (35.5%) cases of ALPIB. Five cases (83.3%) resembling CD were in the active stage with systemic symptoms and multicentric lymphadenopathy. Thirteen cases (92.9%) of APHLF showed systemic symptoms, multicentric lymphadenopathy and abnormal laboratory findings. Histologic findings for cases resembling CD were rare in patients with RA and SjS. In AID patients, histologic findings for cases resembling CD or APHLF findings correlated with disease activity and multicentric lymphadenopathy. Six cases (54.5%) of ALPIB were in the active phase with systemic symptoms and multicentric lymphadenopathy. ALPIB tended to be unrelated to AID activity, especially in the majority of patients with no abnormal laboratory findings. Atypical LPDs associated with AID is a group of diseases that may be overdiagnosed and overtreated. The diagnosis of atypical LPDs associated with AID requires an understanding of the histological findings as well as a comprehensive assessment of the presence of systemic symptoms, the distribution of lymphadenopathy, and abnormal laboratory findings.

Idiopathic multicentric Castleman disease and associated autoimmune and autoinflammatory conditions: practical guidance for diagnosis

Idiopathic multicentric Castleman disease (iMCD) is an infrequent and life-threatening disorder characterised by systemic inflammatory symptoms, generalised lymphadenopathy, polyclonal lymphocyte proliferation, and organ dysfunction caused by a hyperinflammatory state. It accounts for one third to one half of all multicentric Castleman disease (MCD) cases. iMCD is often associated with autoimmune manifestations that may precede the iMCD diagnosis, be identified at the same time or follow it. In addition, iMCD may also coincide with a number of autoimmune diseases (such as psoriasis or myasthenia gravis) or autoinflammatory diseases (such as familial Mediterranean fever). Moreover, diverse inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, adult-onset Still disease, systemic juvenile idiopathic arthritis, immunoglobulin (IgG4) related disease, or the recently described VEXAS syndrome, can present clinical features or lymphadenopathy with histopathological "Castleman-like" findings compatible with those of iMCD. Given the iMCD clinical heterogeneity and the overlap with other autoimmune or autoinflammatory disorders, iMCD diagnosis can be challenging. In this review, we explore the overlap between iMCD and inflammatory diseases and provide practical guidance on iMCD diagnosis in order to avoid misdiagnosis and confusion with other autoimmune or autoinflammatory conditions.

A retrospective study of 44 patients with head and neck Castleman's disease

PURPOSE

To explore the clinical and pathological features, therapy and prognosis of Castleman's disease (CD) in the head and neck.

METHODS

We retrospectively analyzed the clinical and pathological data of 44 patients with head and neck CD who were diagnosed in the Fujian Medical University Union hospital (Fujian, China) between May 2008 and June 2021. According to the clinical classification, they were divided into two groups, the unicentric CD (UCD, n = 20) and the multicentric CD (MCD, n = 24). Their clinical features, imaging findings, laboratory examination, and treatment results were, respectively, analyzed.

RESULTS

The age of UCD patients was younger than that of MCD patients. Most of the UCD patients (80%) were female, with asymptomatic single lymphadenectasis, and the prognosis was favorable; while 70.8% of the MCD patients were male, with multiple lymph nodes throughout the body, and more prone to hepatosplenomegaly, pneumonia, serous effusion, anemia, hypoalbuminemia, elevated globulin, coagulation disorders, etc., the prognosis was bleak. Two cases of MCD patients were with systemic lupus erythematosus (SLE).

CONCLUSIONS

UCD usually manifests as asymptomatic single lymph node enlargement, complete surgical resection was the mainstay of treatment modality. MCD has relatively complicated clinical symptoms and poor prognosis, and anti-IL-6 therapy may be effective.

Clinical characteristics and immunological abnormalities of Castleman disease complicated with autoimmune diseases

Purpose

To explore the clinical features and immunological mechanisms of Castleman disease (CD) complicated with autoimmune diseases (AID).

Methods

We explored the prevalence and clinical manifestations of CD complicated with AID by reviewing clinical, pathological, and laboratory data of 40 CD patients retrospectively, and then explored abnormal immune mechanisms in the co-existence of the two entities by monitoring lymphocyte subsets in peripheral blood.

Results

Paraneoplastic pemphigus, autoimmune hemolytic anemia, Sjogren’s syndrome, myasthenia gravis, and psoriasis were found to be coexisted with CD in 9/40 (22.5%) patients with different sequence of onset. No bias in the clinical and histological type of CD was observed for the occurrence of AID. CD patients with AID were more likely to have skin and/or mucous membrane damage and pulmonary complications, and presented elevated erythrocyte sedimentation rate, hypergammaglobulinemia, and positive autoantibodies than those without AID (p < 0.05). Deregulated cellular and innate immune responses as indicated by decreased CD3⁺ T cells and increased natural killer cells were observed in peripheral blood of CD patients with AID (p < 0.05). UCD patients with AID were successfully treated with surgery and immunosuppressive therapy. MCD complicated by AID relieved with immunosuppressors, cytotoxic chemotherapy, and rituximab.

Conclusion

Systemic inflammation/immunological abnormalities and organ dysfunction were associated with the occurrence of AID in CD. Impairment of cellular and innate immunity may be a candidate etiology for the coexistence of the two entities.

Patients with autoimmune diseases have an altered activity of the PD-1 pathway and proportions of Epstein-Barr virus infected cells in benign lymphadenopathies

Patients with autoimmune diseases (AD) have an increased risk to develop benign lymphadenopathies compared to patients without AD. The aim with this study was to determine the role of the PD-1 pathway and the number of cells harboring Epstein-Barr virus (EBV) in benign lymphadenopathies in patients with AD (cases) compared to patients without AD (controls). Pathology registries were screened to identify patients with biopsies diagnosed as benign lymphadenopathy and medical journals were reviewed for information on AD. Immunohistochemical stainings (PD-1 and PD-L1) and EBER in situ hybridization for EBV were applied on lymph node biopsies in patients with AD (n = 22) and patients without AD (n = 57). The case group was compared with the control group with Wilcoxon-signed rank, chi-square and Fischeŕs exact test. There was a statistically significantly higher proportion of PD-1+ cells and a tendency for a lower prevalence of PD-L1+ and EBV+ cells in cases compared to controls. Apparently, patients with AD have an altered immune response as revealed in benign lymphadenopathies compared to patients without AD. If this association might be a piece of the puzzle for the increased risk of development of lymphomas in patients with AD remains to be determined.

Castleman Disease

Castleman disease (CD) is divided clinically into unicentric or multicentric type. Pathologically, CD is divided into hyaline-vascular and plasma cell variants. Unicentric CD is most common, about 75% of these cases are hyaline-vascular variant, and surgical excision is often curative. In contrast, there are a number of types of multicentric CD including HHV8-associated, idiopathic, and a subset of cases that arise in association with POEMS syndrome. Therapy is required for most patients with multicentric CD, but there is no consensus approach currently. As is evidence, the designation Castleman disease encompasses a heterogeneous group of diseases of varied pathogenesis and which require different therapies.

Chronic CD30 signaling in B cells results in lymphomagenesis by driving the expansion of plasmablasts and B1 cells

CD30 is expressed on a variety of B-cell lymphomas, such as Hodgkin lymphoma, primary effusion lymphoma, and a diffuse large B-cell lymphoma subgroup. In normal tissues, CD30 is expressed on some activated B and T lymphocytes. However, the physiological function of CD30 signaling and its contribution to the generation of CD30⁺ lymphomas are still poorly understood. To gain a better understanding of CD30 signaling in B cells, we studied the expression of CD30 in different murine B-cell populations. We show that B1 cells expressed higher levels of CD30 than B2 cells and that CD30 was upregulated in IRF4⁺ plasmablasts (PBs). Furthermore, we generated and analyzed mice expressing a constitutively active CD30 receptor in B lymphocytes. These mice displayed an increase in B1 cells in the peritoneal cavity (PerC) and secondary lymphoid organs as well as increased numbers of plasma cells (PCs). TI-2 immunization resulted in a further expansion of B1 cells and PCs. We provide evidence that the expanded B1 population in the spleen included a fraction of PBs. CD30 signals seemed to enhance PC differentiation by increasing activation of NF-κB and promoting higher levels of phosphorylated STAT3 and STAT6 and nuclear IRF4. In addition, chronic CD30 signaling led to B-cell lymphomagenesis in aged mice. These lymphomas were localized in the spleen and PerC and had a B1-like/plasmablastic phenotype. We conclude that our mouse model mirrors chronic B-cell activation with increased numbers of CD30⁺ lymphocytes and provides experimental proof that chronic CD30 signaling increases the risk of B-cell lymphomagenesis.

Lymphoproliferative disorders in patients with rheumatoid arthritis in the era of widespread use of methotrexate: A review of the literature and current perspective

Lymphoproliferative disorders (LPD) in patients receiving methotrexate (MTX) have gained strong attention. In this article, I reviewed the basic and clinical findings of this issue. Patients with RA possess a high risk of lymphoma, but epidemiological evidence showing an association between the use of MTX and lymphoma is still limited. Rapid regression of LPD after stopping MTX in patients with RA strongly suggests that there is a causative relationship. Genetic predisposition, accumulated inflammation, impaired generation of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes, effects of MTX on the regulation of EBV genes, and low hypermethylation of apoptosis-related genes are relevant to the development of LPD and rapid regression after cessation of MTX. The clinical and histological characteristics of LPD in RA patients who are treated with MTX have been established, and recent data indicate that initial cessation of MTX and watchful waiting to observe an increase in peripheral lymphocyte counts have a therapeutic value. In advanced cases, various chemotherapy regimens are used, and consultation with hematologists is recommended to select the optimal treatment. There is no consensus on the treatment of RA after development of LPD, and long-term observation is necessary to investigate the safety of disease-modifying antirheumatic drugs in these patients.

TAFRO syndrome with primary Sjogren's syndrome

A 25-year-old woman diagnosed 1 year earlier with Primary Sjogren's syndrome was admitted to a nearby hospital with fever of unknown origin. Examination revealed anasarca, systemic lymphadenopathy, hepatosplenomegaly and high C-reactive protein level. The patient's symptoms were initially suspected to be caused by severe bacterial infection with Sjogren's syndrome flare. She was given antibiotics and prednisolone (PSL) at 50 mg/day. However, the patient developed anemia and thrombocytopenia and was transferred to our hospital for further care. Histological examination of the right inguinal lymph node showed neutrophilic infiltration. Bone marrow aspiration revealed a normocellular marrow with increased megakaryocytes and mild reticulin fiber hyperplasia. After initiation of minocycline hydrochloride, the patient's symptoms improved. However, as PSL was tapered, her symptoms worsened. The patient's clinical symptoms and laboratory data improved again with initiation of intravenous steroid pulse therapy and cyclosporine. TAFRO syndrome is characterized by a constellation of symptoms: Thrombocytopenia, Anasarca, Fever, Reticulin fibrosis and Organomegaly. Although histological findings of the lymph node in this case differed from previous reports, the patient's other symptoms and clinical course were similar to TAFRO syndrome. TAFRO syndrome can occur with several diseases, including infection, rheumatic disease and malignancies. We report a case in which infection might have triggered TAFRO syndrome.

International, evidence-based consensus diagnostic criteria for HHV-8-negative/idiopathic multicentric Castleman disease

Human herpesvirus-8 (HHV-8)-negative, idiopathic multicentric Castleman disease (iMCD) is a rare and life-threatening disorder involving systemic inflammatory symptoms, polyclonal lymphoproliferation, cytopenias, and multiple organ system dysfunction caused by a cytokine storm often including interleukin-6. iMCD accounts for one third to one half of all cases of MCD and can occur in individuals of any age. Accurate diagnosis is challenging, because no standard diagnostic criteria or diagnostic biomarkers currently exist, and there is significant overlap with malignant, autoimmune, and infectious disorders. An international working group comprising 34 pediatric and adult pathology and clinical experts in iMCD and related disorders from 8 countries, including 2 physicians that are also iMCD patients, was convened to establish iMCD diagnostic criteria. The working group reviewed data from 244 cases, met twice, and refined criteria over 15 months (June 2015 to September 2016). The proposed consensus criteria require both Major Criteria (characteristic lymph node histopathology and multicentric lymphadenopathy), at least 2 of 11 Minor Criteria with at least 1 laboratory abnormality, and exclusion of infectious, malignant, and autoimmune disorders that can mimic iMCD. Characteristic histopathologic features may include a constellation of regressed or hyperplastic germinal centers, follicular dendritic cell prominence, hypervascularization, and polytypic plasmacytosis. Laboratory and clinical Minor Criteria include elevated C-reactive protein or erythrocyte sedimentation rate, anemia, thrombocytopenia or thrombocytosis, hypoalbuminemia, renal dysfunction or proteinuria, polyclonal hypergammaglobulinemia, constitutional symptoms, hepatosplenomegaly, effusions or edema, eruptive cherry hemangiomatosis or violaceous papules, and lymphocytic interstitial pneumonitis. iMCD consensus diagnostic criteria will facilitate consistent diagnosis, appropriate treatment, and collaborative research.

The draining lymph node in rheumatoid arthritis: current concepts and research perspectives

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease of unknown aetiology, leading to progressive damage of bone and cartilage with functional impairment and disability. Whilst the synovial membrane represents the epicentre of the immune-inflammatory process, there is growing evidence indicating the potential involvement of additional anatomical compartments, such as the lung, bone marrow, and secondary lymphoid tissues. Draining lymph nodes represent the elective site for tissue immune-surveillance, for the generation of adaptive immune responses and a candidate compartment for the maintenance of peripheral tolerance. Despite the precise role of the juxta- and extra-articular lymph node stations in the pathogenesis of RA remaining poorly defined, several lines of research exploiting new technological approaches are now focusing on their assessment as a potential new source of pathobiologic information, biomarkers, and complementary therapeutic targets. In this review we present an updated overview of the main concepts driving lymph node research in RA, highlighting the most relevant findings, current hypothesis, and translational perspectives.

Clinical features and treatment of multicentric castleman's disease : a retrospective study of 21 Japanese patients at a single institute

Multicentric Castleman's disease (MCD) is a rare polyclonal lymphoproliferative disorder that manifests with lymphadenopathy and inflammatory symptoms. In order to clarify the clinical features and actual management of MCD in Japan, we analyzed 21 patients diagnosed with MCD and treated in Kyoto University Hospital between 2005 and 2012. There were 12 men and 9 women. The median age at disease onset was 46 years, and the median follow-up period was 98 months. Common symptoms included splenomegaly (13/20), renal dysfunction (11/21), interstitial pneumonia (7/21), pleural effusion and/or ascites (7/21), and thrombocytopenia (6/21). The results of the anti-human immunodeficiency virus antibody and human herpes virus-8 DNA tests in the blood were available in 13 and 5 cases, respectively, and no patient was positive for either. Among 12 patients treated with tocilizumab, an anti-interleukin-6 receptor antibody, 11 exhibited an improvement in MCD-related symptoms and 3 achieved complete resolution of all these symptoms. In 8 patients treated with tocilizumab for over 1 year, the mean Hb level increased from 7.4 to 12.2 g/dL while the mean serum C-reactive protein level decreased from 13.2 to 0.4 mg/dL. Three patients died during the observation period due to sepsis, secondary leukemia, or pancreatic cancer. The clinical courses of most cases were indolent; however, in some cases with pleural effusion, ascites, renal dysfunction, and/or thrombocytopenia, the disease manifestation was serious. A nationwide survey is required to further clarify the epidemiology, clinical features, and optimal treatment strategies of MCD in Japan.

A case of rheumatoid arthritis and limited systemic sclerosis overlap successfully treated with tocilizumab for arthritis and concomitant generalized lymphadenopathy and primary biliary cirrhosis

A 57-year-old woman with rheumatoid arthritis (RA) and limited systemic sclerosis (lSSc) was suspected to have lymphadenopathy and primary biliary cirrhosis (PBC). Lymph node biopsy showed reactive follicular lymphadenopathy with intrafollicular plasmacyte infiltration that was interleukin-6 positive by immunohistostaining. Because of gradually worsening arthritis, tocilizumab was administered and arthritis improved markedly. Interestingly, lymphadenopathy and PBC improved simultaneously. This suggested that interleukin-6 might play an important role in reactive lymphadenopathy and PBC associated with RA/lSSc.

HHV-8-negative, idiopathic multicentric Castleman disease: novel insights into biology, pathogenesis, and therapy

Multicentric Castleman's disease (MCD) describes a heterogeneous group of disorders involving proliferation of morphologically benign lymphocytes due to excessive proinflammatory hypercytokinemia, most notably of interleukin-6. Patients demonstrate intense episodes of systemic inflammatory symptoms, polyclonal lymphocyte and plasma cell proliferation, autoimmune manifestations, and organ system impairment. Human herpes virus-8 (HHV-8) drives the hypercytokinemia in all HIV-positive patients and some HIV-negative patients. There is also a group of HIV-negative and HHV-8-negative patients with unknown etiology and pathophysiology, which we propose referring to as idiopathic MCD (iMCD). Here, we synthesize what is known about iMCD pathogenesis, present a new subclassification system, and propose a model of iMCD pathogenesis. MCD should be subdivided into HHV-8-associated MCD and HHV-8-negative MCD or iMCD. The lymphocyte proliferation, histopathology, and systemic features in iMCD are secondary to hypercytokinemia, which can occur with several other diseases. We propose that 1 or more of the following 3 candidate processes may drive iMCD hypercytokinemia: systemic inflammatory disease mechanisms via autoantibodies or inflammatory gene mutations, paraneoplastic syndrome mechanisms via ectopic cytokine secretion, and/or a non-HHV-8 virus. Urgent priorities include elucidating the process driving iMCD hypercytokinemia, identifying the hypercytokine-secreting cell, developing consensus criteria for diagnosis, and building a patient registry to track cases.

Germinal centre protein HGAL promotes lymphoid hyperplasia and amyloidosis via BCR-mediated Syk activation

The human germinal centre associated lymphoma (HGAL) gene is specifically expressed in germinal centre B-lymphocytes and germinal centre-derived B-cell lymphomas, but its function is largely unknown. Here we demonstrate that HGAL directly binds Syk in B-cells, increases its kinase activity upon B-cell receptor stimulation and leads to enhanced activation of Syk downstream effectors. To further investigate these findings in vivo, HGAL transgenic mice were generated. Starting from 12 months of age these mice developed polyclonal B-cell lymphoid hyperplasia, hypergammaglobulinemia and systemic reactive AA amyloidosis, leading to shortened survival. The lymphoid hyperplasia in the HGAL transgenic mice are likely attributable to enhanced B-cell receptor signalling as shown by increased Syk phosphorylation, ex vivo B-cell proliferation and increased RhoA activation. Overall, our study shows for the first time that the germinal centre protein HGAL regulates B-cell receptor signalling in B-lymphocytes which, without appropriate control, may lead to B-cell lymphoproliferation.

[Lymphadenopathy: demarcation to malignant lymphomas]

Recognition of the differential diagnosis between lymphadenitis and malignant lymphoma requires good knowledge of the basic forms of the disease as well in depth knowledge of the structure of the individual compartments. There are defined forms of lymphadenitis where the differential diagnosis to certain lymphoma entities is known. Other reactive structural alterations show indistinct limits so that a decision is only possible after using additional techniques, such as immunohistochemistry and molecular analyses. Finally, there are marginal areas which can only be clarified by including clinical data.

Rheumatoid lymphadenopathy with abundant IgG4(+) plasma cells : a case mimicking IgG4-related disease

Immunoglobulin (Ig) G4-related disease is a recently confirmed clinical entity with several unique clinicopathological features. Here we report a case of rheumatoid lymphadenopathy mimicking IgG4-related disease. The patient was a 63-year-old woman who had been treated for rheumatoid arthritis (RA) for six years. The patient noted cervical lymphadenopathy. Upon radiological examination, systemic lymphadenopathy was detected, and enlarged right brachial lymph node biopsy was performed. Histologically, the lymph node showed marked follicular hyperplasia and interfollicular plasmacytosis without eosinophil infiltration. Although the histological findings were compatible with rheumatoid lymphadenopathy, numerous plasma cells were IgG4(+) (IgG4(+)/IgG(+) plasma cell ratio > 50%). However, laboratory findings revealed elevation of C-reactive protein level, polyclonal hyper-γ-globulinemia, anemia, and hypoalbuminemia. These findings were compatible with hyper-interleukin (IL)-6 syndrome, namely, RA. It is known that hyper-IL-6 syndromes, such as multicentric Castleman's disease, RA, and other autoimmune diseases, fulfill the histological diagnostic criteria for IgG4-related disease. Therefore, hyper-IL-6 syndromes and IgG4-related disease cannot be differentially diagnosed by immunohistochemical staining alone. In conclusion, rheumatoid lymphadenopathy sometimes occurs with abundant IgG4(+) plasma cells, which is required for the differential diagnosis of IgG4-related disease.

Castleman disease

Castleman and Towne described a disease presenting as a mediastinal mass resembling thymoma. It is also known as "giant lymph node hyperplasia", "lymph node hamartoma", "angiofollicular mediastinal lymph node hyperplasia", and "angiomatous lymphoid hyperplasia". The pathogenesis is unknown, but the bulk of evidence points toward faulty immune regulation, resulting in excessive B-lymphocyte and plasma-cell proliferation in lymphatic tissue. In addition to the mediastinal presentation, extrathoracic involvement in the neck, axilla, mesentery, pelvis, pancreas, adrenal gland, and retroperitoneum also have been described. There are 2 major pathologic variations of Castleman disease: (1) hyaline-vascular variant, the most frequent, characterized by small hyaline-vascular follicles and capillary proliferation; and (2) the plasma-cell variant, in which large lymphoid follicles are separated by sheets of plasma cells. The hyaline-vascular cases usually are largely asymptomatic, whereas the less common plasma-cell variant may present with fever, anemia, weight loss, and night sweats, along with polyclonal hypergamma-globulinemia. Castleman disease is a rare lymphoproliferative disorders. Few cases have been described world widely. In this article we reviewed the classification, pathogenesis, pathology, radiological features and up to date treatment with special emphasis on the role of viral stimulation, recent therapeutic modalities and the HIV-associated disease.

Castleman disease and associated autoimmune disease

PURPOSE OF REVIEW

Castleman disease can occur in association with autoimmune connective tissue disease and confound the clinical picture, resulting in delayed diagnosis and suboptimal treatment. This review focuses on the intersection of Castleman disease and autoimmunity with an emphasis on shared pathology and mutually beneficial treatments.

RECENT FINDINGS

Targeting CD-20, interleukin-6, and the nuclear factor-κB pathway has shown promise in achieving long-term remission in patients with Castleman disease and associated autoimmune features.

SUMMARY

Advances in understanding of pathogenic cell types and cytokines in Castleman disease have allowed the development of targeted therapies successful in the treatment of both Castleman disease and associated autoimmune disease.

[How do T-cells become activated in joints?]

Activated CD4+ T-cells are found in joints of patients with rheumatoid arthritis and are involved in the joint destroying autoimmune response. Besides proinflammatory cytokine production T-cells are indispensable for the activation of B-cells, the so-called T-cell help for B-cells. However, the recognition of autoantigens by T-cells seems of utmost importance for the pathogenesis of rheumatoid arthritis. Selective inhibition of this process is therefore one of the most interesting therapeutic targets for the future.

Clinicopathologic correlations of diffuse large B-cell lymphoma in rheumatoid arthritis patients treated with methotrexate

Among methotrexate (MTX)-related lymphoproliferative disorders (MTX-LPD), diffuse large B-cell lymphoma (DLBCL) accounts for about half. We studied the clinicopathological characteristics and prognosis of patients with DLBCL in MTX-LPD. This study included 29 patients who developed DLBCL after receiving MTX for rheumatoid arthritis. MTX was discontinued in all patients. Their median age was 62 years. Elevated lactate dehydrogenase (LDH) level was observed in 97% of the patients, bone marrow involvement in 17%, and involvement of extranodal sites in 41%. As for the cellular immunophenotype, CD20 was positive in 93%, CD5 in 3%, CD10 in 31%, BCL2 in 21%, BCL6 in 69%, and Epstein-Barr virus (EBV)-encoded small non-polyadenylated RNA (EBER) in 24%. Chemotherapy was started within 2 months after MTX withdrawal in 23 patients, of whom 12 patients received combination with rituximab. Spontaneous remission occurred in the remaining six patients. The EEBV-positive rate was 67% (4/6), and the four EBV-positive patients achieved complete response. Among the 23 DLBCL patients treated with chemotherapy, 20 patients achieved complete response. The 5-year overall survival was 74% and the 5-year progression-free survival was 65%. After the development of DLBCL, withdrawal of MTX was the first choice of treatment. Germinal center B-cell type and EBER-positive patients tended to show spontaneous remission. The utility of rituximab should be examined in future studies.

Castleman disease

PURPOSE OF REVIEW

Castleman disease was initially described over 50 years ago as a benign localized mass of lymph nodes found primarily in the mediastinum of asymptomatic patients. Subsequently, additional types were recognized that extend the spectrum of this heterogeneous group of diseases. Optimal standard therapies have not been established. Currently, most patients receive treatments derived from past experience with non-Hodgkin lymphoma that are not altogether satisfactory.

RECENT FINDINGS

Advances in understanding the biological basis of Castleman disease have provided new targets for therapeutic exploitation. Recognition of the role of interleukin-6 in disease perpetuation has led to the use of an antihuman interleukin-6 receptor monoclonal antibody, tocilizumab. Rituximab, an anti-CD20 monoclonal antibody, targets CD20-positive B lymphocytes, a prominent component of this disorder. Human herpes virus-8 and angiogenesis, both involved in the pathogenesis of Castleman disease, may provide additional unique therapeutic opportunities.

SUMMARY

Rational approaches to the treatment of Castleman disease have begun to have an impact on disease management; however, the role of these new agents remains to be established. As the complexity of Castleman disease is more fully understood, additional targets for new innovative therapies undoubtedly will be identified.