Acute hemorrhagic, hepatic, and neurologic manifestations in juvenile rheumatoid arthritis: possible relationship to drugs or infection

Macrophage Activation Syndrome in Children: Update on Diagnosis and Treatment

Macrophage activation syndrome (MAS) is potentially fatal; so, early diagnosis and timely treatment are essential. However, detecting MAS is sometimes challenging because its principal features can be observed in other pediatric diseases that cause severe inflammation. Cytokine storm due to immune dysregulation represents the clinical and laboratory features of MAS that are included in the diagnostic criteria. Most cases of MAS occur as an underlying condition worsens and progresses. Therefore, a patient with autoimmune or autoinflammatory disease who shows unexplained clinical deterioration despite appropriate management should be considered at high risk for MAS (i.e., occult MAS). The basic principles of treatment are control of triggering factors, supportive care, and relief of hyperinflammation. Systemic steroids and cyclosporine A are frequently used as a first-line treatment. For the treatment of refractory MAS, cytokine-specific biologic agents such as anakinra have recently become preferred over traditional immunosuppressive agents such as etoposide. MAS might be underrecognized in pediatric patients with infectious and inflammatory diseases due to its diverse clinical presentations. Clinical suspicion of MAS is of the utmost importance for early recognition of the disease.

The History of Macrophage Activation Syndrome in Autoimmune Diseases

In 1979, it became recognized in the literature that what we call hemophagocytic lymphohistiocytosis (HLH) was a nonmalignant disease of histiocytes. Subsequently a familial form and a secondary form of HLH were differentiated. When HLH is secondary to an autoimmune disease, rheumatologists refer to this entity as macrophage activation syndrome (MAS) to differentiate it from HLH itself. Although the first cases of MAS likely appeared in the literature in the 1970s, it was not until 1985 that the term activated macrophages was used to describe patients with systemic juvenile idiopathic arthritis (sJIA) complicated by MAS and the term macrophage activation syndrome first appeared in the title of a paper in 1993.MAS is one of the many types of secondary HLH and should not be confused with primary HLH. Experience has taught that MAS secondary to different autoimmune diseases is not equal. In the 30 years since initial description in patients with sJIA, the clinical spectrum, diseases associated with MAS, therapy, and understanding the pathogenesis have all made significant gains. The diagnostic/classification criteria for MAS secondary to sJIA, SLE, RA, and KD differ based on the different laboratory abnormalities associated with each (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018). These examples include the thrombocytosis associated with sJIA, a chronic generalized activation of the immune system, leading to elevations of fibrinogen and sIL-2R, low platelet count associated with SLE, and more acute inflammation associated with KD. Therefore, individual diagnostic criteria are required, and they all differ from the diagnostic criteria for HLH, which are based on a previously non-activated immune system (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018; Henter et al., Pediatr Blood Cancer 48:124-131, 2007). This helps to explain why the HLH diagnostic criteria do not perform well in MAS.The initial treatment remains high-dose steroids and IVIG followed by the use of a calcineurin inhibitor for resistant cases. IVIG can be used if there is a concern about malignancy to wait for appropriate investigations or with steroids. Interluekin-1 inhibition is now the next therapy if there is a failure to respond to steroids and calcineurin inhibitors. Advances in understanding the mechanisms leading to MAS, which has been greatly aided by the use of mouse models of MAS and advances in genome sequencing, offer a bright future for more specific therapies. More recent therapies are directed to specific cytokines involved in the pathogenesis of MAS and can lead to decreases in the morbidity and mortality associated with MAS. These include therapies directed to inhibiting the JAK/STAT pathway and/or specific cytokines, interleukin-18 and gamma interferon, which are currently being studied in MAS. These more specific therapies may obviate the need for nonspecific immunosuppressive therapies including high-dose prolonged steroids, calcineurin inhibitors, and etoposide.

Criteria for Cytokine Storm Syndromes

In the past two decades, there has been a great deal of work aimed to devise diagnostic guidelines, classification criteria, and diagnostic scores for cytokine storm syndromes (CSSs). The most notable effort has been the large-scale multinational study that led to the development of the 2016 classification criteria for macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (JIA). Future studies should scrutinize the validity of the proposed criteria, particularly in systemic JIA patients treated with biologics, in children with subtle or incomplete forms of MAS, and in patients with MAS complicating other rheumatologic disorders. More generic CSS criteria are also available but often lack sensitivity and specificity in a wide variety of patient populations and CSSs of different etiologies. The coronavirus disease 2019 (COVID-19)-related lung disease led to an evolution of the concept of a "cytokine storm." Emerging and unsolved challenges in the diagnosis of the different forms of CSSs highlight the need for diagnostic tools and well-established classification criteria to enable timely recognition and correct classification of patients.

Kawasaki Disease-Associated Cytokine Storm Syndrome

Kawasaki disease (KD) is a hyperinflammatory syndrome manifesting as an acute systemic vasculitis characterized by fever, nonsuppurative conjunctival injection, rash, oral mucositis, extremity changes, and cervical lymphadenopathy. KD predominantly affects young children and shares clinical features and immunobiology with other hyperinflammation syndromes including systemic juvenile idiopathic arthritis (sJIA) and multisystem inflammatory syndrome in children (MIS-C). Cytokine storm syndrome (CSS) is an acute complication in ~2% of KD patients; however, the incidence is likely underestimated as many clinical and laboratory features of both diseases overlap. CSS should be entertained when a child with KD is unresponsive to IVIG therapy with recalcitrant fever. Early recognition and prompt institution of immunomodulatory treatment can substantially reduce the mortality and morbidity of CSS in KD. Given the known pathogenetic role of IL-1β in both syndromes, the early use of IL-1 blockers in refractory KD with CSS deserves consideration.

Hemophagocytic Lymphohistiocytosis in Adolescents and Young Adults: Genetic Predisposition and Secondary Disease

Hemophagocytic lymphohistiocytosis (HLH) is a disorder of impaired immune regulation resulting in hyperinflammation that is ultimately fatal if not treated. HLH is categorized into familial disease, caused by genetic mutations affecting the function of cytotoxic T lymphocytes and natural killer cells, and secondary disease, triggered by infections, malignancies, rheumatologic disorders, or immune deficiency. Adolescent and young adults with HLH represent a unique population with specific diagnostic challenges. Here we review the diagnostic criteria, possible etiologies, pathophysiology, and management of HLH with focus on the adolescent population.

Macrophage activation syndrome in a patient with systemic lupus erythematosus undergoing cyclophosphamide treatment: a case report

Macrophage activation syndrome (MAS) is a disorder related to hemophagocytic lymphohistiocytosis and is a life-threatening complication of rheumatic diseases. The diagnosis is challenging because MAS symptoms are quite similar to those of many active autoimmune diseases or severe sepsis. We describe the case of a female patient with systemic lupus erythematosus that presented with symptoms suggesting acute decompensation of autoimmune disease and sepsis. She was later diagnosed with MAS. Despite an aggressive immunosuppressive treatment, she developed a fatal outcome.

Macrophage activation syndrome in adults: Characteristics, outcomes, and therapeutic effectiveness of etoposide-based regimen

Objectives

To describe the clinical characteristics and outcomes of adult macrophage activation syndrome (MAS) patients and to provide experience for the treatment.

Methods

Adult patients with MAS admitted to Beijing Friendship Hospital from December 2014 to September 2021 were enrolled in this study. Clinical data of patients were collected and analyzed.

Results

A total of 118 adult MAS patients entered this study. MAS was the first manifestation in 43 (36.4%) patients, while 75 (63.6%) developed MAS after the diagnosis of autoimmune disease (AID) with a median diagnostic interval of 2 (0.5–359) months. Eighty-two patients were initially treated with glucocorticoid-based regimen; the overall response (OR) rate at the 2-week posttreatment was 37.8%. Forty-five patients switched to etoposide-based regimen, and the OR rate was 84.4%. Thirty-six patients were initially treated with etoposide-based regimen, and the OR rate at the 2-week posttreatment was 80.6%. Serum IL-18 (P = 0.021), IFN-γ (P = 0.013), IP-10 (P = 0.001), IL-10 (P = 0.041), IL-1RA (P < 0.001), and TNF-α (P = 0.020) levels of patients were significantly decreased in the remission phase than in the active phase. Levels of SDF-1α (P = 0.018) and IL-7 (P = 0.022) were higher in refractory patients, while the GRO-α level had a strong tendency toward statistical significance (P = 0.050). The probability of overall survival (OS) at 3, 6, and 36 months after HLH diagnosis were 89.8%, 89.0%, and 87.9%, retrospectively. The active MAS status at the 2-week post initial treatment [P = 0.009, HR = 15.281, 95% CI, (0.1.972, 118.430)] and baseline neutrophil count (Neu) <1.5 × 10⁹/l [P = 0.017, HR = 3.678, 95% CI, (1.267, 10.672)] were negative prognostic factors.

Conclusion

MAS typically occurs within 2 months after the onset of autoimmune disease in adults. SDF-1α, IL-7, and GRO-α could be used to predict refractory MAS. The etoposide-based regimen is effective and tolerable for adult MAS.

Application of Monoclonal Antibody Drugs in Treatment of COVID-19: a Review

Coronavirus infection can have various degrees of severity and outcomes. In some cases, it causes excessive production of pro-inflammatory cytokines, a so-called cytokine storm, leading to acute respiratory distress syndrome. Unfortunately, the exact pathophysiology and treatment, especially for severe cases of COVID-19, are still uncertain. Results of preliminary studies showed that immunosuppressive therapy, such as interleukin (IL)-6, IL-1, and TNF-α antagonists commonly used in rheumatology, can be considered as treatment options for COVID-19, especially in severe cases. The review focused on the most common and currently studied monoclonal antibody drugs, as well as up-to-date data on the pathogenesis of COVID-19, host immune response against SARS-CoV-2 and its association with cytokine storm. It also covered effects of interleukin (IL)-6, IL-1, and TNF-α blockers on the course of coronavirus infection and outcome in patients treated for the main autoimmune disease and subsequently infected with COVID-19.

Infection-Triggered Hyperinflammatory Syndromes in Children

An association between infectious diseases and macrophage activation syndrome (MAS) has been reported, yet the exact role of infection in MAS development is still unclear. Here, a retrospective analysis of the clinical records of patients with rheumatic diseases complicated with MAS who were treated in a pediatric tertiary care center between 2011 and 2020 was performed. Any infection documented within the 30 days preceding the onset of MAS was reported. Out of 125 children in follow-up for systemic rheumatic diseases, 12 developed MAS, with a total of 14 episodes. One patient experienced three episodes of MAS. Clinical and/or laboratory evidence of infection preceded the onset of MAS in 12 events. Clinical features, therapeutic strategies, and patient outcomes were described. The aim of this study was to evaluate the possible role of infection as a relevant trigger for MAS development in children with rheumatic conditions. The pathogenetic pathways involved in the cross-talk between uncontrolled inflammatory activity and the immune response to infection deserve further investigation.

Macrophage activation syndrome triggered by systemic lupus erythematosus flare: successful treatment with a combination of dexamethasone sodium phosphate, intravenous immunoglobulin, and cyclosporine: a case report

Background

Macrophage activation syndrome is classified as a secondary form of hemophagocytic lymphohistiocytosis. It is a hyperinflammatory complication observed to be comorbid with a variety of autoimmune diseases, including adult-onset Still’s disease and systemic juvenile idiopathic arthritis. Macrophage activation syndrome is less commonly detected in adult patients with systemic lupus erythematosus, which, if untreated, can be fatal, though determining the optimum treatment strategy is still a challenge.

Case presentation

Herein, we report a case of macrophage activation syndrome in a 33-year-old Egyptian female as an unusual complication of a systemic lupus erythematosus flare in adult patients. Our patient was initially treated with a combination of intravenous methylprednisolone pulse therapy and intravenous immunoglobulin therapy, which was followed by a course of oral prednisolone and oral cyclosporine with little response. Switching from oral prednisone to intravenous dexamethasone sodium phosphate showed a more favorable clinical and biochemical response.

Conclusion

Macrophage activation syndrome is less commonly detected in adult patients with systemic lupus erythematosus. Our case demonstrates that dexamethasone sodium phosphate can be a successful alternative treatment for patients with systemic lupus erythematosus complicated by macrophage activation syndrome in whom the response to pulse methylprednisolone was inadequate to manage their illness, proving to be remarkably effective in a relatively short time frame.

Still's Disease in the Constellation of Hyperinflammatory Syndromes: A Link with Kawasaki Disease?

Still’s disease and Kawasaki disease (KD) today belong to the group of cytokine storm syndromes, a pathophysiological set related to excessive activation of the innate immune response. We present here a personal vision of what can link these two diseases, taking up their concepts at their beginning. By their many clinical and physiopathological similarities, we conclude that they constitute a common spectrum whose fate is modified by subtle differences in terms of adaptive response that could, in part, be driven by genetic factors.

Macrophage activation syndrome: A diagnostic challenge (Review)

Macrophage activation syndrome (MAS) represents an acute and severe inflammatory syndrome, idiopathic (primary) or secondary to infections, rheumatic diseases, malignancies, or drugs. MAS is underdiagnosed, being confused with sepsis, adverse effects of anti-arthritic drugs or exacerbated symptoms of evolving rheumatologic or infectious diseases. Because of the late diagnosis, most patients do not benefit from effective therapy, leading to death. Elucidation of valid early diagnostic criteria of MAS would be a particularly important step in reducing the mortality due to this pathology. Thus, the purpose of this review based on 40 studies centered on the diagnostic criteria of MAS. We detailed the main diagnostic criteria and the few diagnostic scores or sets of criteria that have been recently published. The criteria most frequently encountered in the literature include: Fever, hepatosplenomegaly, hyperferritinemia, hepatopathy, coagulopathy, thrombocytopenia, hypertriglyceridemia, decrease in erythrocyte sedimentation rate and bone marrow hemophagocytosis. The most elaborate diagnostic score will result following an ongoing international project and consensus, the Delphi International Survey.

Neuropsychological functioning and academic abilities in patients with juvenile idiopathic arthritis

BACKGROUND

The involvement of the central nervous system is not rare in rheumatoid diseases. Even though children with juvenile idiopathic arthritis (JIA) may face academic difficulties until adulthood, very few studies have evaluated potential cognitive disorders in these patients. The present research aims to thoroughly investigate the cognitive and neuropsychological functioning of these patients.

METHODS

We measured the cognitive profile of JIA patients via their neuropsychological profile, implicit memory and social cognition skills, and estimated their academic performance using reading and mathematics tests. We recruited 21 children with JIA aged 6 to 17 years-old (M = 11.01, SD = 3.30) and 21 healthy children matched in age, gender, academic level (same school class) and socioeconomic status.

RESULTS

Our results showed that the cognitive profile and estimated academic ability of JIA patients are similar to those of their peers. These results support the hypothesis that children with JIA have the same cognitive predispositions to succeed at school as any other pupil.

CONCLUSION

Comparing our results with the existing literature, we propose complementary hypotheses for further research. Longitudinal studies seem to be necessary to understand the psychosocial and cognitive processes involved in the development of children with JIA.

Macrophage activation syndrome in children with Kawasaki disease: diagnostic and therapeutic approaches

BACKGROUND

Macrophage activation syndrome (MAS) is a rare, life-threatening complication of Kawasaki disease (KD). Early recognition and treatment of MAS are very important, but sometimes it is difficult to distinguish MAS from a severe form of KD.

DATA SOURCES

A PubMed search was performed in Clinical Queries using the key terms "macrophage activation syndrome or secondary hemophagocytic lymphohistiocytosis (HLH)" and "Kawasaki disease".

RESULTS

KD patients with MAS show high intravenous immunoglobulin (IVIG) resistance and coronary complications. Mortality is also as high as MAS in other diseases. Persistent fever greater than 10 days is highly associated with development of MAS in KD. Splenomegaly is observed in more than two-thirds of KD patients with MAS. Thrombocytopenia is often the earliest laboratory finding of MAS. Hyperferritinemia is highly specific and sensitive for detecting MAS in KD; so, ferritin levels should be checked if there are unexplained clinical exacerbations in KD patients. Given the under-recognition of MAS in KD, it is prudent to consider resistant KD as occult/subclinical MAS. Many KD patients with MAS have good outcomes on immune modulators. However, if KD patients fulfill the HLH-2004 diagnostic criteria, they may undergo longer and more intensive treatment than needed.

CONCLUSIONS

The possible existence of MAS should be taken into account when a KD patient shows persistent fever, splenomegaly, thrombocytopenia, hyperferritinemia, or IVIG resistance. The under-diagnosis of MAS in patients with KD is an important issue to be addressed. Therapeutically, however, there is a possibility of over-treatment of MAS in patients with KD.

COVID-19 and Hyperinflammatory Syndrome in Children: Kawasaki Disease with Macrophage Activation Syndrome in Disguise?

A hyperinflammatory syndrome has been described in times of COVID-19 in children. In the setting of uncertainty due to a new virus, the so-called hyperinflammatory syndrome has been coined as a novel entity by some and is being referred to as pediatric inflammatory multisystem syndrome (PIMS). However, the characteristics of the syndrome resemble those of Kawasaki disease (KD), an inflammatory syndrome in children that can lead to coronary artery abnormalities due to a subsequent vasculitis. Furthermore, Kawasaki disease may occasionally trigger macrophage activation syndrome (MAS), a condition in which there is uncontrolled activation and proliferation of macrophages and other cell types, and could lead to multiorgan system dysfunction. This study provides a review of the data regarding COVID-19, Kawasaki disease, and macrophage activation syndrome to demonstrate the similarities and differences between the inflammatory syndrome seen with COVID-19 and KD. In addition, a framework for diagnosis and evaluation is provided that focuses on the pathway previously established for KD and MAS. The authors believe that based on current knowledge, KD treatment delays may carry deleterious effects in the near future for children with COVID-19-related Kawasaki disease.

Immune Pathogenesis of COVID-19 Intoxication: Storm or Silence?

Dysregulation of the immune system undoubtedly plays an important and, perhaps, determining role in the COVID-19 pathogenesis. While the main treatment of the COVID-19 intoxication is focused on neutralizing the excessive inflammatory response, it is worth considering an equally significant problem of the immunosuppressive conditions including immuno-paralysis, which lead to the secondary infection. Therefore, choosing a treatment strategy for the immune-mediated complications of coronavirus infection, one has to pass between Scylla and Charybdis, so that, in the fight against the "cytokine storm," it is vital not to miss the point of the immune silence that turns into immuno-paralysis.

Hemophagocytic lymphohistiocytosis: a review inspired by the COVID-19 pandemic

Hemophagocytic syndrome (HPS) or hemophagocytic lymphohistiocytosis (HLH) is an acute and rapidly progressive systemic inflammatory disorder characterized by cytopenia, excessive cytokine production, and hyperferritinemia. Common clinical manifestations of HLH are acute unremitting fever, lymphadenopathy, hepatosplenomegaly, and multiorgan failure. Due to a massive cytokine release, this clinical condition is considered as a cytokine storm syndrome. HPS has primary and acquired (secondary, reactive) forms. Its primary form is mostly seen in childhood and caused by various mutations with genetic inheritance and, therefore, is called familial HLH. Secondary HLH may be caused in the presence of an underlying disorder, that is, secondary to a malignant, infectious, or autoimmune/autoinflammatory stimulus. This paper aims to review the pathogenesis and the clinical picture of HLH, and its severe complication, the cytokine storm, with a special emphasis on the developed classification criteria sets for rheumatologists, since COVID-19 infection has clinical symptoms resembling those of the common rheumatologic conditions and possibly triggers HLH. MED-LINE/Pubmed was searched from inception to April 2020, and the following terms were used for data searching: “hemophagocytic syndrome” OR “macrophage activation syndrome” OR “hemophagocytic lymphohistiocytosis”, OR “cytokine storm”. Finally, AND “COVID-19” was included in this algorithm. The selection is restricted to the past 5 years and limited numbers of earlier key references were manually selected. Only full-text manuscripts, published in an English language peer-reviewed journal were included. Manuscript selection procedure and numbers are given in Fig. 2. Briefly, the database search with the following terms of “Hemophagocytic syndrome” OR “Macrophage activation syndrome” OR “Hemophagocytic lymphohistiocytosis” OR “Cytokine storm” yielded 6744 results from inception to April 2020. The selection is restricted to the past 5 years and only limited numbers of earlier key references were selected, and this algorithm resulted in 3080 manuscripts. The addition of (AND “COVID-19”) resulted in 115 publications of which 47 studies, together with four sections of an online book were used in the final review. No statistical method was used. HLH is triggered by genetic conditions, infections, malignancies, autoimmune-autoinflammatory diseases, and some drugs. In COVID-19 patients, secondary HLH and cytokine storm may be responsible for unexplained progressive fever, cytopenia, ARDS, neurological and renal impairment. Differentiation between the primary and secondary forms of HLH is utterly important, since primary form of HLH requires complicated treatments such as hematopoietic stem cell transplantation. Further studies addressing the performance of HScore and other recommendations in the classification of these patients is necessary.

Treatment outcomes and prognostic factors for non- malignancy associated secondary hemophagocytic lymphohistiocytosis in children

BACKGROUND

Secondary hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory syndrome that requires prompt diagnosis and appropriate treatment. A risk-stratification model that could be used to identify high-risk pediatric patients with HLH who should be considered for second-line therapies, including salvage regimens and allogeneic hematopoietic cell transplantation (HCT), was developed.

METHODS

The medical records of 88 pediatric patients (median age 1.4 years, range 0.2-15 years) with non-malignancy associated secondary HLH were retrospectively reviewed. Treatment strategies included dexamethasone, etoposide, and cyclosporine.

RESULTS

Survival analysis showed HLH patients with infections other than Epstein-Barr virus (EBV) and unknown causes experienced better 5-year overall survival (OS) than patients with HLH due to autoimmune disease, EBV or immunodeficiency (76% vs. 65, 33.3, 11%, p < 0.001). On multivariate analysis, among all patients, non-response at 8 weeks was the most powerful predictor of poor OS. When treatment response was excluded, hemoglobin < 60 g/L and albumin < 25 g/L at diagnosis were associated with poor OS. In patients with EBV-HLH, hemoglobin < 60 g/L at diagnosis was associated with poor OS. A prognostic risk score was established and weighted based on hazard ratios calculated for three parameters measured at diagnosis: hemoglobin < 60 g/L (2 points), platelets < 30 × 10⁹/L (1 point), albumin < 25 g/L (2 points). Five-year OS of low-risk (score 0-1), intermediate-risk (score 2), and poor-risk (score ≥ 3) patients were 88, 38, and 22%, respectively (p < 0.001).

CONCLUSIONS

These findings indicate that clinicians should be aware of predictive factors at diagnosis and consider 8-week treatment response to identify patients with high-risk of disease progression and the need for second-line therapy and allogeneic HCT.

Hemophagocytic lymphohistiocytosis: An update on pathogenesis, diagnosis, and therapy

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening state of immune hyperactivation that arises in the setting of genetic mutations and infectious, inflammatory, or neoplastic triggers. Sustained, aberrant activation of cytotoxic CD8⁺ T cells and resultant inflammatory cytokine release are core pathogenic mechanisms. Key clinical features include high persistent fever, hepatosplenomegaly, blood cytopenia, elevated aminotransferase and ferritin levels, and coagulopathy. HLH is likely under-recognized, and mortality remains high, especially in adults; thus, prompt diagnosis and treatment are essential. Familial forms of HLH are currently treated with chemotherapy as a bridge to hematopoietic stem cell transplantation. HLH occurring in rheumatic disease (macrophage activation syndrome) is treated with glucocorticoids, IL-1 blockade, or cyclosporine A. In other forms of HLH, addressing the underlying trigger is essential. There remains a pressing need for more sensitive, context-specific diagnostic tools. Safer, more effective therapies will arise with improved understanding of the cellular and molecular mechanisms of HLH.

Macrophage Activation Syndrome and Secondary Hemophagocytic Lymphohistiocytosis in Childhood Inflammatory Disorders: Diagnosis and Management

Macrophage activation syndrome (MAS), a form of secondary hemophagocytic lymphohistiocytosis, is a frequently fatal complication of a variety of pediatric inflammatory disorders. MAS has been most commonly associated with systemic juvenile idiopathic arthritis (sJIA), as approximately 10% of children with sJIA develop fulminant MAS, with another 30-40% exhibiting a more subclinical form of the disease. Children with other rheumatologic conditions such as systemic lupus erythematosus and Kawasaki disease are also at risk for MAS. Moreover, MAS also complicates various genetic autoinflammatory disorders such as gain of function mutations in the cytosolic inflammasome NLRC4, pediatric hematologic malignancies (e.g., T-cell lymphoma), and primary immunodeficiencies characterized by immune dysregulation. Disease-specific and broadly inclusive diagnostic criteria have been developed to facilitate the diagnosis of MAS. Recently, simple screening tools such as the serum ferritin to erythrocyte sedimentation rate ratio have been proposed. Early diagnosis and rapid initiation of immunosuppression are essential for the effective management of MAS. With a better understanding of the pathophysiology of MAS and the advent of novel therapeutics, a broad immunosuppressive approach to treatment is giving way to targeted anti-cytokine therapies. These treatments include agents that block interleukin-1 (IL-1), IL-6, IL-18, interferon-γ, as well as inhibitors of downstream targets of cytokine signaling (e.g., Janus kinases). Increased early recognition of MAS among pediatric inflammatory disorders combined with the use of effective and less toxic cytokine-targeted therapies should lower the mortality of this frequently fatal disorder.

[Adult-onset Still's disease complications]

Adult-onset Still's disease (AOSD), first described in 1971 by Bywaters, is a rare systemic auto-inflammatory disorder of unknown etiology, characterized by a symptomatic triad associating prolonged fever, polyarthritis and rash. The management of this disease has significantly improved since its first description, and, although the overall prognosis of the AOSD is good, with a low attributable mortality, below 3% (but up to 18% depending on the series), some rare complications are still possible, can be life-threatening and change the prognosis of the disease. A literature search was performed to review AOSD's complications: reactive hemophagocytic lymphohystiocytosis, coagulation disorders, fulminant hepatitis, cardiovascular (pericarditis, myocarditis, HTAP) or pulmonary complications, neurologic, renal complications, and AA amyloidosis. For most of AOSD-related complications, corticosteroids remain the first-line treatment, in association with supportive care measures in case of severe complications. In case of inadequate response, multidisciplinary care with concil from a referral center is advised, and IL-1 or IL-6 blockers, but also ciclosporine, are the molecule to use in second intention.

Challenges in the diagnosis of hemophagocytic lymphohistiocytosis: Recommendations from the North American Consortium for Histiocytosis (NACHO)

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic immune activation, often associated with genetic defects of lymphocyte cytotoxicity. Though a distinctive constellation of features has been described for HLH, diagnosis remains challenging as patients have diverse presentations associated with a variety of triggers. We propose two concepts to clarify how HLH is diagnosed and treated: within the broader syndrome of HLH, "HLH disease" should be distinguished from "HLH disease mimics" and HLH subtypes should be categorized by specific etiologic associations, not the ambiguous dichotomy of "primary" and "secondary." We provide expert-based advice regarding the diagnosis and initiation of treatment for patients with HLH, rooted in improved understanding of its pathophysiology.

Macrophage activation syndrome in adults: recent advances in pathophysiology, diagnosis and treatment

Haemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome, which if not promptly treated, can lead rapidly to critical illness and death. HLH is termed macrophage activation syndrome (MAS) when associated with rheumatic disease (where it is best characterized in systemic JIA) and secondary HLH (sHLH) when associated with other triggers including malignancy and infection. MAS/sHLH is rare and coupled with its mimicry of other conditions, is underrecognized. These inherent challenges can lead to diagnostic and management challenges in multiple medical specialties including haematology, infectious diseases, critical care and rheumatology. In this review we highlight the pathogenesis of MAS/sHLH including its underlying triggers, key clinical features and diagnostic challenges, prognostic factors and current treatments in adults.

[Still's disease in children and adults]

Systemic juvenile idiopathic arthritis (sJIA) is characterized by fever, arthritis, and other signs of systemic inflammation. Historically, sJIA was named Still's disease after George Frederic Still, who first reported patients. Individuals who manifest after the 16^th birthday are diagnosed with adult onset Still's disease (AOSD). The pathophysiology of sJIA and AOSD are incompletely understood. Increased activation of inflammasomes and the expression of proinflammatory cytokines play a central role. S100 proteins, which can activate Toll-like receptors, thus, maintaining positive feedback loops, have also been detected at increased levels in sera from sJIA patients. Reduced expression of the immune-modulatory cytokine IL-10 may further contribute to immune cell activation and the production of proinflammatory molecules. Here, we discuss the clinical picture, differential diagnoses, the current pathophysiological understanding, and treatment options in sJIA and AOSD.

Convergent pathways of the hyperferritinemic syndromes

Hyperferritinemia and pronounced hemophagocytosis help distinguish a subset of patients with a particularly inflammatory and deadly systemic inflammatory response syndrome. Two clinically similar disorders typify these hyperferritinemic syndromes: hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS). HLH is canonically associated with a complete disturbance of perforin/granzyme-mediated cytotoxicity, whereas MAS occurs in the context of the related rheumatic diseases systemic juvenile idiopathic arthritis and adult-onset Still's disease, with associated IL-1 family cytokine activation. In practice, however, there are accumulating lines of evidence for innate immune dysregulation in HLH as well as partial impairments of cytotoxicity in MAS, and these mechanisms likely represent only a fraction of the host and environmental factors driving hyperferritinemic inflammation. Herein, we present new findings that highlight the pathogenic differences between HLH and MAS, two conditions that present with life-threatening hyperinflammation, hyperferritinemia and hemophagocytosis.

The Immunology of Macrophage Activation Syndrome

Synonymous with secondary hemophagocytic lymphohistiocytosis, macrophage activation syndrome (MAS) is a term used by rheumatologists to describe a potentially life-threatening complication of systemic inflammatory disorders, most commonly systemic juvenile idiopathic arthritis (sJIA) and systemic lupus erythematosus (SLE). Clinical and laboratory features of MAS include sustained fever, hyperferritinemia, pancytopenia, fibrinolytic coagulopathy, and liver dysfunction. Soluble interleukin-2 receptor alpha chain (sCD25) and sCD163 may be elevated, and histopathology often reveals characteristic increased hemophagocytic activity in the bone marrow (and other tissues), with positive CD163 (histiocyte) staining. A common hypothesis as to the pathophysiology of many cases of MAS proposes a defect in lymphocyte cytolytic activity. Specific heterozygous gene mutations in familial HLH-associated cytolytic pathway genes (e.g., PRF1, UNC13D) have been linked to a substantial subset of MAS patients. In addition, the pro-inflammatory cytokine environment, particularly IL-6, has been shown to decrease NK cell cytolytic function. The inability of NK cells and cytolytic CD8 T cells to lyse infected and otherwise activated antigen presenting cells results in prolonged cell-to-cell (innate and adaptive immune cells) interactions and amplification of a pro-inflammatory cytokine cascade. The cytokine storm results in activation of macrophages, causing hemophagocytosis, as well as contributing to multi-organ dysfunction. In addition to macrophages, dendritic cells likely play a critical role in antigen presentation to cytolytic lymphocytes, as well as contributing to cytokine expression. Several cytokines, including tumor necrosis factor, interferon-gamma, and numerous interleukins (i.e., IL-1, IL-6, IL-18, IL-33), have been implicated in the cytokine cascade. In addition to broadly immunosuppressive therapies, novel cytokine targeted treatments are being explored to dampen the overly active immune response that is responsible for much of the pathology seen in MAS.

Characteristics of bone marrow cells in 107 patients with juvenile idiopathic arthritis: A retrospective study

Few studies to date have reported on the myelodysplastic features of children with juvenile idiopathic arthritis (JIA). Bone marrow specimens were collected from 107 patients aged from 7-12 years who were initially diagnosed with JIA between May 2013 and October 2015. In 107 patients with JIA, bone marrow proliferation was higher than normal and hemophagocytes were more easily observed than usual. The characteristics of bone marrow cells in 107 patients with JIA were investigated and the associations of these characteristics with the disease was discussed in the present study. It was noticed that there were similar changes in the myeloid, erythropoietic and megakaryopoietic series in the majority of bone marrow specimens; the presence of hemophagocytes was also reported. The present findings suggest that JIA is associated with specific myelodysplastic changes, and that cellular immune system dysfunction and overreactive inflammatory cytokines may contribute to the development of these myelodysplastic changes in the bone marrow.

A prospective quality improvement initiative in adult hemophagocytic lymphohistiocytosis to improve testing and a framework to facilitate trigger identification and mitigate hemorrhage from retrospective analysis

Hemophagocytic lymphohistiocytosis (HLH) is a highly fatal, hyperinflammatory syndrome in adults triggered by an underlying illness in most cases. As such, suspicion of HLH dictates further investigation to identify the HLH trigger and determine treatment. HLH is clinically challenging due to diverse presentations and underlying triggers, provider unfamiliarity, and bleeding complications. Clinically, we observed diagnostic error from incorrect testing and cognitive biases (interleukin-2 confused with soluble interleukin-2 receptor and natural killer cell quantification confused with functional assays).This study reports our single institutional experience with adult HLH with the aim to reduce erroneous testing with a quality improvement (QI) project, and to facilitate trigger discovery and mitigate hemorrhage. Provider education on HLH testing was the prospective intervention, followed by mistaken test removal. HLH triggers and diagnostic utility were determined by retrospective chart review. Risk factors for hemorrhage were determined by multivariable analysis.Erroneous HLH testing was reduced from 74% to 24% of patients (P < .001) by the QI intervention. These changes were projected to save $11,700 yearly. The majority (64%) of patients evaluated for HLH were on non-hematology/oncology services, highlighting the need for vigilance in hematology consultation. Sixty-three patients met classic HLH-2004 criteria for HLH. Malignancy (38%), infection (27%), Epstein-Barr virus (EBV) (14%), or autoimmune disease (8%) triggered most HLH cases. HLH triggers were most commonly identified by serologic testing (27%) and bone marrow biopsy (19%). Biopsy of other affected organs based on PET-CT imaging after unsuccessful initial diagnostic measures was helpful, and focal fluorodeoxyglucose uptake was predictive of an underlying malignancy (likelihood ratio 8.3, P = .004). Major hemorrhage occurred in 41% of patients. On multivariable analysis the odds ratios (OR) for major hemorrhage were increased for patients with intensive care unit level care (OR 10.47, P = .005), and disseminated intravascular coagulation in the first week of admission (OR 10.53, P = .04).These data are incorporated into a framework to encourage early HLH recognition with the HScore, facilitate trigger identification, identify those at risk for hemorrhage, and minimize low-yield or erroneous testing.

Severe hemophagocytic lymphohistiocytosis in a melanoma patient treated with ipilimumab + nivolumab

BACKGROUND

Treatment of metastatic melanoma patients with immune checkpoint inhibitors is an important standard of care. Side effects are due to immune activation, can affect virtually all organ systems, and are occasionally severe. Although hematologic toxicity has been reported, we present a case of hemophagocytic lymphohistiocytosis (HLH) due to immune checkpoint inhibitor therapy.

CASE PRESENTATION

A patient with metastatic melanoma was treated with one course of ipilimumab + nivolumab and presented 3 weeks later with severe anemia and hyperferritinemia. A bone marrow biopsy revealed necrotic tumor cells, infiltrating T cells, and hemophagocytosis. The patient was treated with high-dose steroids; 12 months later, the patient remains off all therapy and in complete remission of both HLH and metastatic melanoma.

CONCLUSIONS

The hemophagocytic syndromes are attributable to dysregulated immune activation and share pathophysiologic mechanisms with immune activation from checkpoint inhibitors. Increasing use of regimens that include immune checkpoint inhibition require vigilant monitoring for immune-activating side effects as they can occasionally be life threatening, as in this case of HLH.

Hemophagocytic Lymphohistiocytosis Complicating Systemic Sarcoidosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening hyperinflammatory syndrome characterized by histiocyte proliferation and hemophagocytosis. Primary HLH is caused by genetic defects, whereas secondary HLH occurs in the setting of underlying diseases, such as infections, malignancies, or rheumatic diseases. Rheumatic diseases, such as systemic juvenile arthritis or systemic lupus erythematosus, have been associated with HLH. However, the association between sarcoidosis and HLH has been rarely reported in the literature. Herein, we report a case of a 36-year-old female who was recently diagnosed with sarcoidosis, and she developed fatal HLH that was not responsive to high-dose steroids.

Macrophage Activation Syndrome

Hemophagocytic lymphohistiocytosis (HLH), or termed macrophage activation syndrome (MAS) when associated with rheumatic disorders, is a frequently fatal complication of infections, rheumatic disorders, and hematopoietic malignancies. Clinically, HLH/MAS is a life-threatening condition that is usually diagnosed among febrile hospitalized patients (children and adults) who commonly present with unremitting fever and a shock-like multiorgan dysfunction scenario. Laboratory studies reveal pancytopenia, elevated liver enzymes, elevated markers of inflammation (ESR, CRP), hyperferritinemia, and features of coagulopathy. In about 60% of cases, excess hemophagocytosis (macrophages/histiocytes engulfing other hematopoietic cell types) is noted on biopsy specimens from the bone marrow, liver, lymph nodes, and other organs. HLH/MAS has been hypothesized to occur when a threshold level of inflammation has been achieved, and genetic and environmental risk factors are believed to contribute to the hyperinflammatory state. A broad variety of infections, from viruses to fungi to bacteria, have been identified as triggers of HLH/MAS, either in isolation or in addition to an underlying inflammatory disease state. Certain infections, particularly by members of the herpesvirus family, are the most notorious triggers of HLH/MAS. Treatment for infection-triggered MAS requires therapy for both the underlying infection and dampening of the hyperactive immune response.

The influence of various therapeutic regimens on early clinical and laboratory response and outcome of children with secondary hemophagocytic lymphohistiocytosis

INTRODUCTION

Secondary hemophagocytic lymphohistiocytosis (sHLH) is a life-threatening syndrome of severe hyperinflammation which is often triggered by infection or autoimmune disease (macrophage activation syndrome - MAS). The aim of our study was to assess the frequency of sHLH/MAS in children treated in our institution and to compare the effectiveness of various therapeutic interventions.

MATERIAL AND METHODS

Between 2005 and 2013, 24 children (age: 1-17 years) were consecutively treated for sHLH/MAS. Therapy was based on glucocorticoids (GCs) in high or standard doses (hd-GCs or sd-GCs), intravenous immunoglobulin (IVIG), and cyclosporin A (CyA). A comparison of selected laboratory and clinical parameters during the first 72 h of treatment and after a week from the last intervention applied in the first 72 h after diagnosis was performed retrospectively.

RESULTS

The majority of patients (14/24, 58%) suffered from sHLH/MAS in the course of an autoimmune disease (12 patients diagnosed with a systemic form of juvenile idiopathic arthritis). We found with a confidence level of 95% that the application of hd-GCs in the first 24 h caused rapid alleviation of fever, reduction of hepatosplenomegaly, and an increase in thrombocytes and s-fibrinogen concentrations. The use of combination therapy with hd-GCs, IVIG, and CyA in the first 72 h caused a faster increase in s-fibrinogen. All patients survived and were alive at the follow-up of 1-8 years.

CONCLUSIONS

The results indicate that treatment of sHLH/MAS based on hd-GCs, CyA and IVIG is an effective therapy in children.

Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis is a life-threatening disorder characterized by unbridled activation of cytotoxic T lymphocytes, natural killer (NK) cells, and macrophages resulting in hypercytokinemia and immune-mediated injury of multiple organ systems. It is seen in both children and adults and is recognized as primary (driven by underlying genetic mutations that abolish critical proteins required for normal function of cytotoxic T cells and NK cells) or secondary (resulting from a malignant, infectious, or autoimmune stimulus without an identifiable underlying genetic trigger). Clinical and laboratory manifestations include fever, splenomegaly, neurologic dysfunction, coagulopathy, liver dysfunction, cytopenias, hypertriglyceridemia, hyperferritinemia, hemophagocytosis, and diminished NK cell activity. It is treated with immune suppressants, etoposide, and allogeneic hematopoietic stem cell transplantation; more than 50% of children who undergo transplant survive, but adults have quite poor outcomes even with aggressive management. Newer agents directed at subduing the uncontrolled immune response in a targeted fashion offer promise in this highly morbid disease.

[Still's disease in children and adults]

Systemic juvenile idiopathic arthritis (sJIA) is characterized by fever, arthritis, and other signs of systemic inflammation. Historically, sJIA was named Still's disease after George Frederic Still, who first reported patients. Individuals who manifest after the 16^th birthday are diagnosed with adult onset Still's disease (AOSD). The pathophysiology of sJIA and AOSD are incompletely understood. Increased activation of inflammasomes and the expression of proinflammatory cytokines play a central role. S100 proteins, which can activate Toll-like receptors, thus, maintaining positive feedback loops, have also been detected at increased levels in sera from sJIA patients. Reduced expression of the immune-modulatory cytokine IL-10 may further contribute to immune cell activation and the production of proinflammatory molecules. Here, we discuss the clinical picture, differential diagnoses, the current pathophysiological understanding, and treatment options in sJIA and AOSD.

Plasma exchange successfully treated macrophage activation syndrome in rheumatoid factor-positive polyarticular juvenile idiopathic arthritis with co-existing pneumonia

Macrophage activation syndrome (MAS) is one of the serious complications associated with rheumatic diseases, especially systemic juvenile idiopathic arthritis (sJIA). Here we describe a 9-year-old girl with rheumatoid factor (RF)-positive polyarticular JIA, not sJIA, combined with pneumonia who was successfully treated by plasma exchange. She was diagnosed with RF-positive polyarticular JIA based on positive RF and multiple joint swelling and tenderness 3 years ago. She was admitted in our hospital with myalgia for 2 days and a high fever for half a day. Physical examination revealed relapsing joints symptoms and rough breathing sounds of lungs. The laboratory examination showed increased liver enzymes, elevated serum ferritin and procalcitonin (PCT), decreased percentage of nature killer (NK) cells and fibrinogen, and activated macrophage phagocytosing hematopoietic elements in bone marrow. The elevated PCT and chest computed tomography scan confirmed she also had pneumonia. Intravenous methylprednisolone and oral cyclosporine A followed by intravenous immunoglobulin were added on the basis of antibiotics therapy, but clinical symptoms and laboratory findings did not improve. Finally, we changed to plasma exchange once every other day for a total of three times. Within 1 week, the girl recovered from the MAS completely.

Review: Macrophage activation syndrome in juvenile systemic lupus erythematosus: an under-recognized complication?

Macrophage activation syndrome (MAS) is a life-threatening complication of rheumatic diseases that is thought to be caused by the activation and uncontrolled proliferation of T lymphocytes and macrophages, leading to widespread haemophagocytosis and cytokine overproduction. It is seen most commonly in systemic juvenile idiopathic arthritis, but is increasingly recognized also in juvenile systemic lupus erythematosus (J-SLE). Recognition of MAS in patients with J-SLE is often challenging because it may mimic the clinical features of the underlying disease or be confused with an infectious complication. This review summarizes the characteristics of patients with J-SLEassociated MAS reported in the literature or seen by the authors and analyses the distinctive clinical, diagnostic and therapeutic issues that the occurrence of MAS may raise in patients with J-SLE. Lupus (2007) 16, 587—592.

Rate and Clinical Presentation of Macrophage Activation Syndrome in Patients With Systemic Juvenile Idiopathic Arthritis Treated With Canakinumab

OBJECTIVE

In pivotal trials, canakinumab has been shown to be effective in the treatment of systemic juvenile idiopathic arthritis (JIA), but reported adverse events have included macrophage activation syndrome (MAS). This study was undertaken to assess the impact of canakinumab on MAS incidence.

METHODS

An independent MAS Adjudication Committee (MASAC), consisting of 3 of the authors, was convened, and a search of databases from clinical studies of canakinumab treatment in systemic JIA was performed using MASAC-specified adverse event terms to identify potential MAS events. These were then adjudicated as "probable MAS," "possible MAS," or "MAS unlikely," using criteria developed by the MASAC. MAS rates were expressed as numbers of cases per 100 patient-years.

RESULTS

Of 72 potential MAS cases identified, 21 events (19 with canakinumab treatment; 2 with placebo treatment) in 19 patients were adjudicated as being probable MAS and 10 events in 9 patients as being possible MAS. Systemic JIA was well controlled in the majority of canakinumab-treated patients at the time of MAS. The time period between initiation of canakinumab treatment and onset of MAS ranged from 3 to 1,358 days (median 292 days). When the rates of probable MAS events were compared between canakinumab-treated patients (2.8 per 100 patient-years) and placebo-treated patients (7.7 per 100 patient-years), the difference was not significant (-4.9 [95% confidence interval -15.6, 5.9]). There were 3 deaths due to MAS-related complications (2 in patients receiving canakinumab; 1 in a patient receiving placebo); full recovery was reported in all other patients. Infections were the most common trigger of MAS, and the clinical features of MAS were not modified by canakinumab.

CONCLUSION

Canakinumab does not have a significant effect on MAS risk or its clinical features in patients with systemic JIA. Infections are the most common trigger, and MAS occurs even in patients whose systemic JIA is well controlled with this treatment.

Macrophage activation syndrome in the era of biologic therapy

Macrophage activation syndrome (MAS) refers to acute overwhelming inflammation caused by a 'cytokine storm'. Although increasingly recognized as a life-threatening complication of various rheumatic diseases, clinically, MAS is strikingly similar to primary and secondary forms of haemophagocytic lymphohistiocytosis (HLH). Not surprisingly, many rheumatologists prefer the term secondary HLH rather than MAS to describe this condition, and efforts to change the nomenclature are in progress. The pathophysiology of MAS remains elusive, but observations in animal models, as well as data on the effects of new anticytokine therapies on rates and clinical presentations of MAS in patients with systemic juvenile idiopathic arthritis (sJIA), provide clues to the understanding of this perplexing clinical phenomenon. In this Review, we explore the latest available evidence and discuss potential diagnostic challenges in the era of increasing use of biologic therapies.

Macrophage activation syndrome in a patient with systemic onset of the juvenile idiopathic arthritis

Systemic onset juvenile idiopathic arthritis (sJIA) is defined as arthritis affecting one or more joint usually in the juvenile age group (< 16 years of age) with or preceded by fever of at least 2 weeks duration that is documented to be daily ("quotidian") for at least 3 days which may be associated with evanescent (non-fixed) erythematous rash or generalized lymph node enlargement or hepatomegaly/splenomegaly/both or serositis. Macrophage activation syndrome (MAS) is a life-threatening complication of sJIA marked by sudden onset of non-remitting high fever, profound depression in all three blood cell lines (i.e. leukopenia, anemia, and thrombocytopenia), hepatosplenomegaly, lymphadenopathy, and elevated serum liver enzyme levels. In children with systemic juvenile idiopathic arthritis, the clinical picture may mimic sepsis or an exacerbation of the underlying disease. We report a case of a 16-year-old female patient presenting with high grade fever with joint pains and generalized weakness which proved to be systemic onset juvenile idiopathic arthritis with macrophage activation syndrome after ruling out all other differential diagnoses and responded well to intravenous steroids.

Macrophage Activation Syndrome

Macrophage activation syndrome (MAS) is a potentially life-threatening complication of rheumatic disorders that occurs most commonly in systemic juvenile idiopathic arthritis. In recent years, there have been several advances in the understanding of the pathophysiology of MAS. Furthermore, new classification criteria have been developed. Although the place of cytokine blockers in the management of MAS is still unclear, interleukin-1 inhibitors represent a promising adjunctive therapy, particularly in refractory cases.

Macrophage activation syndrome or septic arthritis: a case of mistaken identity

We present an interesting case of macrophage activation syndrome in a 2-year-old, with no previous rheumatological diagnoses, incorrectly diagnosed with septic arthritis, to highlight the diagnostic difficulties, especially in small hospital units. We aim to present the similarities between the two conditions and to summarize the clinical, radiological and epidemiological features of macrophage activation syndrome, an underdiagnosed condition. A review of the current literature was performed, and a diagnostic algorithm was created. No current set treatment regimen exists, but current recommendations have been included. We have demonstrated the pitfalls in diagnosis and the importance of immediate treatment in optimizing prognosis.