International definition of iMCD-TAFRO: future perspectives

The Involvement of PI3K-Akt Signaling in the Clinical and Pathological Findings of Idiopathic Multicentric Castleman Disease-Thrombocytopenia, Anasarca, Fever, Reticulin Fibrosis, and Organomegaly and Not Otherwise Specified Subtypes

Idiopathic multicentric Castleman disease is a rare lymphoproliferative disorder that is clinically classified into idiopathic plasmacytic lymphadenopathy (IPL); thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly (TAFRO); and not otherwise specified (NOS). Although each subtype shows varying degrees of hypervascularity, no statistical data on the degree of vascularization have been reported. Additionally, the mechanisms underlying vascularization in each clinical subtype are poorly understood. Here, we aimed to clarify these mechanisms by evaluating the histopathological characteristics of each clinical subtype across 37 patients and performing a whole-transcriptome analysis focusing on angiogenesis-related gene expression. Histologically, TAFRO and NOS exhibited a significantly higher degree of vascularization than IPL (IPL vs TAFRO, P < .001; IPL vs NOS, P = .002). In addition, the germinal centers (GCs) were significantly more atrophic in TAFRO than in IPL. In TAFRO and NOS, "whirlpool vessels" in GCs were seen in most cases (TAFRO, 9/9, 100%; NOS, 6/8, 75%) but not in IPL (IPL vs TAFRO, P < .001; IPL vs NOS, P = .007). Likewise, immunostaining for Ets-related gene revealed higher levels in endothelial cells of GCs in TAFRO than in IPL (P = .014), and TAFRO and NOS were associated with a significantly higher number of endothelial cells in interfollicular areas compared with that in IPL (TAFRO vs IPL, P < .001; NOS vs IPL, P = .002). Gene expression analysis revealed that the PI3K-Akt signaling pathway was significantly enriched in the TAFRO and NOS (TAFRO/NOS) groups. This pathway, which may be activated by vascular endothelial growth factor A and some integrins, is known to affect angiogenesis by increasing vascular permeability, which may explain the clinical manifestations of anasarca and/or fluid retention in TAFRO/NOS. These results suggest that the PI3K-Akt pathway plays an important role in the pathogenesis of TAFRO/NOS.

Successful Treatment of Refractory TAFRO Syndrome with Cyclophosphamide: A Report of Two Cases

TAFRO syndrome is a rare, severe, and sometimes refractory condition characterized by thrombocytopenia, anasarca, a fever, reticulin myelofibrosis, and organomegaly. Although several treatment options have been proposed for this condition, there are few reported cases in the literature on successful treatment using cyclophosphamide in patients with TAFRO syndrome. We herein report two cases of refractory TAFRO syndrome successfully treated with intravenous cyclophosphamide. In both cases, after the initial treatment with high-dose glucocorticoids and tocilizumab failed, the administration of intravenous cyclophosphamide led to significant improvement. These cases suggest that intravenous cyclophosphamide may be a viable therapeutic option for refractory TAFRO syndromes.

Exploring the Clinical Diversity of Castleman Disease and TAFRO Syndrome: A Japanese Multicenter Study on Lymph Node Distribution Patterns

Individuals diagnosed with Castleman disease (CD) and TAFRO syndrome (characterized by thrombocytopenia, anasarca, fever, bone marrow fibrosis, and organomegaly) displays a wide range of clinical symptoms, including varying patterns of lymph node enlargement, systemic inflammation, and impaired organ function. Some patients may present with both CD and TAFRO syndrome concurrently. A retrospective study conducted across multiple centers in Japan examined 321 cases to determine if the quantity and position of swollen lymph nodes could forecast the clinical progression and intensity of these conditions. Interestingly, the study revealed that patients with TAFRO syndrome exhibited lymphadenopathy across all ranges of lymph node region counts. Moreover, no specific clinical patterns were associated with the number of affected lymph node regions in CD patients, regardless of whether they also had TAFRO syndrome. These results enhance our understanding of the clinical variability in CD and TAFRO syndrome, suggesting that a comprehensive clinical evaluation, rather than relying solely on lymph node count, is crucial for effectively managing these conditions. Additional studies are required to establish reliable diagnostic markers and to predict disease severity at the time of diagnosis, ultimately improving patient outcomes.

Epstein-Barr virus-encoded RNA-positive lymphocytes in bone marrow and lymph nodes in an autopsy case of TAFRO syndrome

A 55-year-old man was admitted to the hospital with vomiting, diarrhoea, and chest pain. Upon examination, he exhibited signs of increased inflammatory response, acute kidney injury, and thrombocytopenia, leading to a diagnosis of TAFRO syndrome, which was supported by the clinical evidence of generalised lymphadenopathy, pleural effusion, and hepatosplenomegaly. Despite receiving intensive multimodal immunosuppressive therapy, including glucocorticoid pulse therapy (methylprednisolone 1000 mg/day), tocilizumab, and cyclosporine in the intensive care unit, the patient showed minimal response and succumbed to the disease on the seventh day of hospitalisation. Histopathological analysis of the lymph nodes revealed idiopathic multicentric Castleman disease-like features, and Epstein-Barr virus-encoded RNA (EBER) in situ hybridisation identified multiple EBER-positive cells. These findings highlight the elusive pathogenic mechanism of TAFRO syndrome and the potential resistance of some patients to standard treatments such as tocilizumab. The presence of EBER-positive cells in lymph nodes or bone marrow may serve as an indicator of disease severity and treatment resistance. Therefore, histopathological detection of EBER-positive cells may help predict responsiveness to conventional treatments, disease severity, and prognosis in patients with TAFRO syndrome.

Transcriptome analysis of the cytokine storm-related genes among the subtypes of idiopathic multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a type of Castleman disease unrelated to the Kaposi sarcoma-associated herpesvirus/human herpesvirus type 8 (KSHV/HHV8) infection. Presently, iMCD is classified into iMCD-IPL (idiopathic plasmacytic lymphadenopathy), iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis/renal insufficiency, and organomegaly), and iMCD-NOS (not otherwise specified). The most common treatment for iMCD is using IL-6 inhibitors; however, some patients resist IL-6 inhibitors, especially for iMCD-TAFRO/NOS. Nevertheless, since serum IL-6 levels are not significantly different between the iMCD-IPL and iMCD-TAFRO/NOS cases, cytokines other than IL-6 may be responsible for the differences in pathogenesis. Herein, we performed a transcriptome analysis of cytokine storm-related genes and examined the differences between iMCD-IPL and iMCD-TAFRO/NOS. The results demonstrated that counts per million of STAT2, IL1R1, IL1RAP, IL33, TAFAIP1, and VEGFA (P < 0.001); STAT3, JAK2, MAPK8, IL17RA, IL18, TAFAIP2, TAFAIP3, PDGFA, VEGFC, CXCL10, CCL4, and CXCL13 (P < 0.01); and STAT1, STAT6, JAK1, MAPK1, MAPK3, MAPK6, MAPK7, MAPK9, MAPK10, MAPK11, MAPK12, MAPK14, NFKB1, NFKBIA, NFKBIB, NFKBIZ, MTOR, IL10RB, IL12RB2, IL18BP, TAFAIP6, TNFAIP8L1, TNFAIP8L3, CSF2RBP1, PDGFB, PDGFC, and CXCL9 (P < 0.05) were significantly increased in iMCD-TAFRO/NOS. Particularly, upregulated IL33 expression was demonstrated for the first time in iMCD-TAFRO/NOS. Thus, inflammatory signaling, such as JAK-STAT and MAPK, may be enhanced in iMCD-TAFRO/NOS and may be a cytokine storm.

Immunology and targeted therapy in Castleman disease

INTRODUCTION

Castleman disease (CD) is a benign lymphoproliferative disease causing severe systemic inflammation. Interleukin-6 (IL-6) is a major pathogenesis of multicentric CD (MCD), but only 30-60% of patients respond to IL-6 inhibitors. Novel agents for IL-6 inhibitor-refractory cases are needed. Clinical data and samples are being collected on a large scale and the clinical, pathological, and pathogenetic aspects are being elucidated.

AREAS COVERED

The pathological and clinical classification of CD is outlined. Focusing on idiopathic MCD (iMCD), this review identifies therapeutic targets and summarizes currently recommended drugs and promising therapeutic candidates.

EXPERT OPINION

The pathogenesis of MCD has been implicated in the activation of the Janus kinase (JAK)-transcriptional signaling activator (STAT) 3 pathway and the phosphatidylinositol 3-kinase (PI3K)/Akt/mechanical target of rapamycin (mTOR) signaling pathway. iMCD-TAFRO (thrombocytopenia, anasarca, fever/elevated CRP, reticulin myelofibrosis/renal dysfunction, organ enlargement) is resistant to IL-6 inhibitors, and cyclosporine and mTOR inhibitors are sometimes effective. JAK inhibitors and mTOR inhibitors may be therapeutic agents for iMCD. Recently, we have shown that peripheral helper T (Tph) cell abnormalities are at the core of iMCD pathogenesis. Therapies targeting chemokine (C-X-C motif) ligand 13 (CXCL13) produced by Tph cells and blocking the Tph-CXCL13-B cell pathway may satisfy unmet need in refractory cases.

Increase in Vascular Endothelial Growth Factor (VEGF) Expression and the Pathogenesis of iMCD-TAFRO

TAFRO (thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis (F/R), renal failure (R), and organomegaly (O)) is a heterogeneous clinical subtype of idiopathic multicentric Castleman disease (iMCD) associated with a significantly poorer prognosis than other subtypes of iMCD. TAFRO symptomatology can also be seen in pathological contexts outside of iMCD, but it is unclear if those cases should be considered representative of a different disease entity or simply a severe presentation of other infectious, malignant, and rheumatological diseases. While interleukin-6 (IL-6) is an established driver of iMCD-TAFRO pathogenesis in a subset of patients, the etiology is unknown. Recent case reports and literature reviews on TAFRO patients suggest that vascular endothelial growth factor (VEGF), and the interplay of VEGF and IL-6 in concert, rather than IL-6 as a single cytokine, may be drivers for iMCD-TAFRO pathophysiology, especially renal injury. In this review, we discuss the possible role of VEGF in the pathophysiology and clinical manifestations of iMCD-TAFRO. In particular, VEGF may be involved in iMCD-TAFRO pathology through its ability to activate RAS/RAF/MEK/ERK and PI3K/AKT/mTOR signaling pathways. Further elucidating a role for the VEGF-IL-6 axis and additional disease drivers may shed light on therapeutic options for the treatment of TAFRO patients who do not respond to, or otherwise relapse following, treatment with IL-6 targeting drugs. This review investigates the potential role of VEGF in the pathophysiology of iMCD-TAFRO and the potential for targeting related signaling pathways in the future.

TAFRO Syndrome and COVID-19

TAFRO syndrome is a systemic inflammatory disease characterized by thrombocytopenia and anasarca. It results from hyperinflammation and produces severe cytokine storms. Severe acute respiratory syndrome coronavirus 2, which led to the coronavirus disease 2019 (COVID-19) pandemic, also causes cytokine storms. COVID-19 was reported to be associated with various immune-related manifestations, including multisystem inflammatory syndrome, hemophagocytic syndrome, vasculitis, and immune thrombocytopenia. Although the pathogenesis and complications of COVID-19 have not been fully elucidated, the pathogeneses of excessive immunoreaction after COVID-19 and TAFRO syndrome both involve cytokine storms. Since the COVID-19 pandemic, there have been a few case reports about the onset of TAFRO syndrome after COVID-19 or COVID-19 vaccination. Castleman disease also presents with excessive cytokine production. We reviewed the literature about the association between TAFRO syndrome or Castleman disease and COVID-19 or vaccination against it. While the similarities and differences between the pathogeneses of TAFRO syndrome and COVID-19 have not been investigated previously, the cytokines and genetic factors associated with TAFRO syndrome and COVID-19 were reviewed by examining case reports. Investigation of TAFRO-like manifestations after COVID-19 or vaccination against COVID-19 may contribute to understanding the pathogenesis of TAFRO syndrome.

TAFRO Syndrome: Guidance for Managing Patients Presenting Thrombocytopenia, Anasarca, Fever, Reticulin Fibrosis, Renal Insufficiency, and Organomegaly

TAFRO syndrome is an inflammatory disorder of unknown etiology characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis, renal insufficiency, and organomegaly. Despite great advancements in research on the TAFRO syndrome in the last decade, its diagnosis and treatment are still challenging for most clinicians because of its rarity and severity. Since the initial proposal of the TAFRO syndrome as a distinct disease entity in 2010, two independent diagnostic criteria have been developed. Although these are different in the concept of whether TAFRO syndrome is a subtype of idiopathic multicentric Castleman disease or not, they are similar except for the magnitude of lymph node histopathology. Because there have been no specific biomarkers, numerous diseases must be ruled out before the diagnosis of TAFRO syndrome is made. The standard of care has not been fully established, but interleukin-6 blockade therapy with siltuximab or tocilizumab and anti-inflammatory therapy with high-dose corticosteroids are the most commonly applied for the treatment of TAFRO syndrome. The other immune suppressive agents or combination cytotoxic chemotherapies are considered for patients who do not respond to the initial treatment. Whereas glowing awareness of this disease improves the clinical outcomes of patients with TAFRO syndrome, further worldwide collaborations are warranted.

Successful outcome in a case of idiopathic multicentric Castleman disease with atypical lymphadenopathy and kidney injury: Diagnostic challenges and treatment approach-Case report

Idiopathic multicentric Castleman disease is a rare and complex disease characterized by systemic inflammation, lymphadenopathy, and multiorgan involvement. This case report presents a 66-year-old Chinese man with idiopathic multicenter Castleman disease without significant lymphadenopathy and challenging diagnosis. Patients present with fever, fatigue, loss of appetite, weight loss, and acute kidney injury. Initially, a urinary tract infection was suspected, but despite anti-infective treatment, the patient's symptoms persisted. Lymph node biopsy, although there is no significant lymphadenopathy, confirms idiopathic multicenter Castleman disease. Treatment includes thalidomide, cyclophosphamide, and dexamethasone, as well as supportive measures and infection control. After 8 months of follow-up, the patient's clinical symptoms, inflammatory markers and renal function were significantly improved, and there was no symptomatic recurrence. This case underscores the importance of considering idiopathic multicenter Castleman's disease in patients with persistent fever and systemic inflammation, even in the absence of significant lymphadenopathy. Early identification and accurate diagnosis of idiopathic multicenter Castleman's disease can lead to the initiation of targeted therapy strategies that ultimately yield favorable outcomes.

Diagnostic challenges of the idiopathic plasmacytic lymphadenopathy (IPL) subtype of idiopathic multicentric Castleman disease (iMCD): Factors to differentiate from IgG4-related disease

AIMS AND METHODS

Idiopathic multicentric Castleman disease (iMCD) is currently considered to be classified into three clinical subtypes, including idiopathic plasmacytic lymphadenopathy (IPL), thrombocytopaenia, anasarca, fever, reticulin fibrosis/renal dysfunction, organomegaly (TAFRO) and not otherwise specified (NOS). Among the three, iMCD-IPL closely mimics IgG4-related disease (IgG4-RD). In diagnosing IgG4-RD, it is sometimes challenging to distinguish iMCD-IPL patients that also meet the histological diagnostic criteria for IgG4-RD. In this study, we focused on the number of IgG4-positive cells in the lymph nodes and analysed the relationship with laboratory findings to distinguish iMCD-IPL from IgG4-RD. Thirty-nine patients with iMCD-IPL and 22 patients with IgG4-RD were included.

RESULTS

Among the cases considered to be iMCD-IPL, 33.3% (13/39) cases also met the histological diagnostic criteria for IgG4-RD and serum IgG4 levels were not different between the two groups. However, the serum IgG4/IgG ratio was significantly higher in IgG4-RD, with a cut-off value of 19.0%. Additionally, a significant positive correlation between serum IgG levels and the number of IgG4-positive cells was observed in iMCD-IPL (p=0.001). The serum IgG cut-off value for distinguishing iMCD-IPL meeting histological criteria for IgG4-RD from other iMCD-IPL was 5381 mg/dL.

CONCLUSIONS

iMCD-IPL cases with high serum IgG levels (>5000 mg/dL) were likely to meet the diagnostic criteria for IgG4-RD because of the numerous IgG4-positive cells observed. A combination of clinical presentations, laboratory values including the serum IgG4/IgG ratios and histological analysis is crucial for diagnosis of IgG4-RD and iMCD-IPL.

Computed tomography findings of idiopathic multicentric Castleman disease subtypes

This study retrospectively evaluated the computed tomography (CT) findings of idiopathic multicentric Castleman disease (iMCD) at a single center and compared the CT findings of iMCD-TAFRO with those of iMCD-non-TAFRO. CT images obtained within 30 days before diagnostic confirmation were reviewed for 20 patients with iMCD (8 men and 12 women, mean age 52.8 ± 12.3 years, range 25-74 years). Twelve patients were diagnosed with iMCD-TAFRO, five with iMCD-idiopathic plasmacytic lymphadenopathy, and three with iMCD-not otherwise specified. CT images revealed anasarca and lymphadenopathy in all 20 patients. The iMCD-TAFRO group showed significantly higher frequencies of ascites (100% vs. 37.5%, P = 0.004), gallbladder wall edema (75.0% vs. 12.5%, P = 0.020), periportal collar (91.7% vs. 25.0%, P = 0.004), and anterior mediastinal lesions (non-mass-forming infiltrative lesions) (66.7% vs. 12.5%, P = 0.028). Para-aortic edema tended to be more frequent in patients with the iMCD-TAFRO group (83.3% vs. 37.5%, P = 0.062), while the absence of anterior mediastinal lesions tended to be more frequent in the iMCD-non-TAFRO group (16.7% vs. 62.5%, P = 0.062). These CT findings may have clinical implications for improving the accuracy and speed of iMCD diagnosis and differentiating iMCD-TAFRO from other subtypes.

Approche thérapeutique des maladies de Castleman : l’émergence des thérapies ciblées

The spectrum of Castleman disease encompasses several different disorders. Nowadays three different forms of the disease are individualized: unicentric Castleman disease, multicentric HHV-8 associated Castleman disease and idiopathic multicentric Castleman disease. In the latter a severe form called TAFRO syndrome (thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly) tend to be individualized. Improvement in the classification and understanding of the physiopathology of CD have allowed improvement in treatment strategies. Treatment of rare but often severe manifestations, such as paraneoplastic pemphigus and bronchiolitis obliterans in unicentric CD and hemophagocytic syndrome and/or Kaposi' sarcoma in HHV8 associated CD, are better adapted. Most of current treatment strategies are based on retrospective and very few prospective studies. Both anti-IL6/6R and anti-CD20 biotherapies have greatly improved the management of certain forms of the disease. We report in this review the most relevant studies and national or international expert consensus statements for the treatment in the different types of CD. © 2022 Published by Elsevier Masson SAS on behalf of Société nationale française de médecine interne (SNFMI).

Idiopathic Plasmacytic Lymphadenopathy Forms an Independent Subtype of Idiopathic Multicentric Castleman Disease

Idiopathic multicentric Castleman disease (iMCD) is a type of Castleman disease that is not related to KSHV/HHV8 infection. Currently, iMCD is classified into iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly) and iMCD-NOS (not otherwise specified). The former has been established as a relatively homogeneous disease unit that has been recently re-defined, while the latter is considered to be a heterogeneous disease that could be further divided into several subtypes. In 1980, Mori et al. proposed the concept of idiopathic plasmacytic lymphadenopathy (IPL), a disease presenting with polyclonal hypergammaglobulinemia and a sheet-like proliferation of mature plasma cells in the lymph nodes. Some researchers consider IPL to be a part of iMCD-NOS, although it has not been clearly defined to date. This is the first paper to analyze iMCD-NOS clinicopathologically, to examine whether IPL forms a uniform disease unit in iMCD. Histologically, the IPL group showed prominent plasmacytosis and the hyperplasia of germinal centers, while the non-IPL group showed prominent vascularity. Clinically, the IPL group showed significant thrombocytosis and elevated serum IgG levels compared to the non-IPL group (p = 0.007, p < 0.001, respectively). Pleural effusion and ascites were less common in the IPL group (p < 0.001). The IPL group was more likely to have an indolent clinical course and a good response to the anti-IL-6 receptor antibody, while the non-IPL counterpart frequently required more aggressive medical interventions. Thus, the IPL group is a clinicopathologically uniform entity that forms an independent subtype of iMCD.