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Abstract Background Haemophagocytic lymphohistiocytosis (HLH) is a syndrome that occurs in patients with severe systemic hyperinflammation. GATA binding protein 2 (GATA2) is a transcription factor and key component in haematopoiesis and stem cell biology. Case presentation Three patients with HLH, one with Mycobacterium avium infection, one with Epstein–Barr virus (EBV) infection, and one with Mycobacterium kansasii infection, were all subsequently found to have a defect in the GATA2 gene through genetic testing. Conclusions GATA2 deficiency syndrome should be considered in patients with myelodysplastic syndrome, nontuberculous mycobacterium infection and HLH. In addition, the GATA2 gene variant may be a genetic defect that could be the cause of the primary HLH. However, further studies are needed to confirm the role of GATA2 pathogenic variants in the pathogenesis of HLH.

Haemophagocytic lymphohistiocytosis (HLH) affects patients across all age groups and can be classified as either primary HLH (P-HLH) or secondary HLH (S-HLH). The latter is associated with clinical conditions that disrupt normal immunological responses, such as infections, neoplasms or autoimmune diseases. Although HLH can occur sporadically in healthy individuals, it is more frequently observed in patients with haematological malignancies and autoimmune disorders. The diagnostic process for HLH is often challenging due to its non-specific signs and the absence of pathognomonic findings. The primary objective in treating S-HLH is to eliminate the underlying trigger and control immunological hyperactivation, making the identification and treatment of triggers critically important. Prompt diagnosis and treatment are essential, as the mortality rate remains high. In this context, we present the case of a young woman diagnosed with idiopathic S-HLH, likely triggered by a bacterial infection. The diagnosis was achieved due to a high index of clinical suspicion for S-HLH. The patient exhibited an excellent response to antimicrobial therapy, resulting in the complete resolution of haemophagocytosis. The authors deem it important to present this case to enhance awareness of S-HLH diagnosis, as well as the investigation and management of potential triggers.

ABSTRACTObjective: An association exists between immune checkpoint inhibitors and hemophagocytic lymphohistiocytosis (HLH). Therefore, the main objective of this study was to collect data on this rare but potentially life-threatening immune-related adverse reaction to identify the medications that cause it, the clinical characteristics, and effective treatments.Methods: Literature in English and Chinese on immune checkpoint inhibitors causing HLH published from August 2014 to March 2024 was analyzed. Immune checkpoint inhibitors, immunotherapy, anti-PD-1, PD-L1 inhibitors, HLH, hemophagocytic lymphohistiocytosis, hemophagocytic syndrome keywords were used to find the literature on China Knowledge Network, Wanfang, PubMed and Emabase Databases.Results and discussion: Twenty-four studies were included, with a total of 27 patients (18 males and 9 females) with a mean age of 58 years (range 26–86). The mean time to the onset of symptoms was 10.3 weeks (7 days–14 months). The main clinical characteristics were fever, cytopenia, splenomegaly, methemoglobinemia, hypofibrinogenemia, and bone marrow biopsy showed phagocytosis. Twenty-two patients improved after the treatment with steroids, cytokine blocking therapy and symptomatic treatment, four patients died, and one patient was not described.Conclusion: HLH should be not underestimated as a potentially serious adverse effect of immune checkpoint inhibitors since appropriate treatments may save the life of patients.

After the announcement of the coronavirus disease 2019 (COVID-19) pandemic, a new disease connected with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection was described: paediatric multisystem inflammatory syndrome associated with coronavirus disease (PIMS). PIMS is an acute and potentially dangerous inflammatory syndrome that may lead to cardiac complications. It requires differential diagnosis with Kawasaki disease. Some patients with PIMS can develop macrophage activation syndrome (MAS), which until now has occurred most commonly with systemic-onset juvenile idiopathic arthritis (JIA) and is closely related to haemophagocytic lymphohistiocytosis (HLH). In this article we present a case report of a patient with diagnosed PIMS, including PIMS with MAS, and with later diagnosis of HLH and JIA. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) is a rare, aggressive, excess immune activation syndrome. Diagnosis can be challenging due to its several clinical mimics including sepsis. There are multiple aetiologies of HLH; in adults, it is most commonly triggered by infection, malignancy, drugs and autoimmune processes. Failure to rapidly diagnose and treat this condition can be fatal. The management of HLH includes identifying and removing the trigger, supportive management and immunosuppression. Identifying the trigger is essential to inform the most appropriate type of immunosuppression. Here, we report a case of likely drug-induced HLH in a patient recently treated for hairy cell leukaemia. The culprit drug was thought to be co-trimoxazole and this case report highlights a very rare complication of this commonly used drug. We discuss our management approach with steroid monotherapy and withdrawal of co-trimoxazole. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis is a severe systemic hyperinflammatory syndrome characterised by dysregulation of immune cells and excessive production of cytokines, also known as a cytokine storm. It has distinctive clinical features with fever, hyperferritinaemia and falling blood counts. In adults, this usually occurs secondary to an underlying driver or trigger including infection, malignancy or rheumatic diseases. Prompt treatment with immunomodulatory therapy, including corticosteroids and the recombinant IL-1 receptor antagonist anakinra, is recommended to switch off the cytokine storm. Etoposide-based regimens are sometimes needed, and newer therapies such as emapalumab and JAK inhibitors are increasingly being used. The incidence of haemophagocytic lymphohistiocytosis has increased significantly over the last 20 years which may partly reflect increased awareness of the condition. Although relatively rare, haemophagocytic lymphohistiocytosis can be encountered by a broad range of hospital physicians, so knowing how to diagnose and treat this condition is essential. This article reviews the pathogenesis, clinical features, causes, diagnosis and treatment of haemophagocytic lymphohistiocytosis to improve physician recognition and management of this condition to improve future patient outcomes. [ABSTRACT FROM AUTHOR]

Abstract Background Chimeric antigen receptor T-cell (CAR-T) therapy is increasingly used in patients with refractory haematological malignancies but can induce severe adverse events. We aimed to describe the clinical features and outcomes of patients admitted to the intensive care unit (ICU) after CAR-T therapy. Methods This retrospective observational cohort study included consecutive adults admitted to either of two French ICUs in 2018–2022 within 3 months after CAR-T therapy. Results Among 238 patients given CAR-T therapy, 84 (35.3%) required ICU admission and were included in the study, a median of 5 [0–7] days after CAR-T infusion. Median SOFA and SAPSII scores were 3 [2–6] and 39 [30–48], respectively. Criteria for cytokine release syndrome were met in 80/84 (95.2%) patients, including 18/80 (22.5%) with grade 3–4 toxicity. Immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 46/84 (54.8%) patients, including 29/46 (63%) with grade 3–4 toxicity. Haemophagocytic lymphohistiocytosis was diagnosed in 15/84 (17.9%) patients. Tocilizumab was used in 73/84 (86.9%) patients, with a median of 2 [1–4] doses. Steroids were given to 55/84 (65.5%) patients, including 21/55 (38.2%) given high-dose pulse therapy. Overall, 23/84 (27.4%) patients had bacterial infections, 3/84 (3.6%) had fungal infections (1 invasive pulmonary aspergillosis and 2 Mucorales), and 2 (2.4%) had cytomegalovirus infection. Vasopressors were required in 23/84 (27.4%), invasive mechanical ventilation in 12/84 (14.3%), and dialysis in 4/84 (4.8%) patients. Four patients died in the ICU (including 2 after ICU readmission, i.e., overall mortality was 4.8% of patients). One year after CAR-T therapy, 41/84 (48.9%) patients were alive and in complete remission, 14/84 (16.7%) were alive and in relapse, and 29/84 (34.5%) had died. These outcomes were similar to those of patients never admitted to the ICU. Conclusion ICU admission is common after CAR-T therapy and is usually performed to manage specific toxicities. Our experience is encouraging, with low ICU mortality despite a high rate of grade 3–4 toxicities, and half of patients being alive and in complete remission at one year.

We report a case of an adult female with disseminated tuberculosis, cytomegalovirus viraemia and haemophagocytic-lymphohistiocystosis syndrome associated with neutralizing anti- interferon gamma (IFNγ) autoantibodies demonstrated by absent IFNγ stimulated STAT1 phosphorylation in the presence of patient sera. A brief review of immunodeficiency caused by anti-IFNγ autoantibodies is also described.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy is increasingly used in patients with refractory haematological malignancies but can induce severe adverse events. We aimed to describe the clinical features and outcomes of patients admitted to the intensive care unit (ICU) after CAR-T therapy. Methods: This retrospective observational cohort study included consecutive adults admitted to either of two French ICUs in 2018–2022 within 3 months after CAR-T therapy. Results: Among 238 patients given CAR-T therapy, 84 (35.3%) required ICU admission and were included in the study, a median of 5 [0–7] days after CAR-T infusion. Median SOFA and SAPSII scores were 3 [2–6] and 39 [30–48], respectively. Criteria for cytokine release syndrome were met in 80/84 (95.2%) patients, including 18/80 (22.5%) with grade 3–4 toxicity. Immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 46/84 (54.8%) patients, including 29/46 (63%) with grade 3–4 toxicity. Haemophagocytic lymphohistiocytosis was diagnosed in 15/84 (17.9%) patients. Tocilizumab was used in 73/84 (86.9%) patients, with a median of 2 [1–4] doses. Steroids were given to 55/84 (65.5%) patients, including 21/55 (38.2%) given high-dose pulse therapy. Overall, 23/84 (27.4%) patients had bacterial infections, 3/84 (3.6%) had fungal infections (1 invasive pulmonary aspergillosis and 2 Mucorales), and 2 (2.4%) had cytomegalovirus infection. Vasopressors were required in 23/84 (27.4%), invasive mechanical ventilation in 12/84 (14.3%), and dialysis in 4/84 (4.8%) patients. Four patients died in the ICU (including 2 after ICU readmission, i.e., overall mortality was 4.8% of patients). One year after CAR-T therapy, 41/84 (48.9%) patients were alive and in complete remission, 14/84 (16.7%) were alive and in relapse, and 29/84 (34.5%) had died. These outcomes were similar to those of patients never admitted to the ICU. Conclusion: ICU admission is common after CAR-T therapy and is usually performed to manage specific toxicities. Our experience is encouraging, with low ICU mortality despite a high rate of grade 3–4 toxicities, and half of patients being alive and in complete remission at one year. [ABSTRACT FROM AUTHOR]

Background: Patients with advanced HIV can present with multiple life-threatening pathologies. Disseminated histoplasmosis is an underdiagnosed infection in advanced HIV which can lead to haemophagocytic lymphohistiocytosis (HLH). Case report: A 36-year-old woman originally from Nigeria was admitted with a two-month history of weight loss, fevers and a papular rash. She was diagnosed with advanced HIV with a CD4 count of 5 cells/mm3 and was pancytopaenic. She spiked fevers despite broad-spectrum antimicrobial therapy. Elevated ferritin and triglycerides levels with haemophagocytosis on bone marrow biopsy indicated HLH; she was treated with immunosuppressive therapy. Mycobacterial blood cultures grew Mycobacterium avium-intracellulare (MAI). She also had an Abiotrophia defectiva bacteraemia, Staphylococcus epidermidis line infection and cytomegalovirus viraemia. Despite treatment of her conditions, the patient deteriorated requiring ICU admission. Blood cultures eventually grew Histoplasma capsulatum. Biopsy of the rash showed fungal elements. She was treated for disseminated histoplasmosis (DH) with antifungals and improved. Discussion: Management of patients with advanced HIV who have multiple pathologies and numerous drug therapies relies on effective multi-disciplinary team involvement. Despite early diagnosis of advanced HIV and early consideration for HLH, there was a significant delay in diagnosis of DH, a condition with a high mortality. This delay was due to factors including the initial attribution of pancytopaenia and fever to HLH and MAI infection instead of DH, as well as the slow growth of H. capsulatum in cultures and lack of alternative diagnostics. Conclusion: Awareness of DH as a cause of HLH in the context of advanced HIV is crucial. Early diagnosis and treatment of both HLH and DH in the context of advanced HIV is associated with improved survival.

Haemophagocytic lymphohistiocytosis (HLH) is a rare disorder. This study sheds light on a rare and intriguing case of HLH as the initial symptom in a child with Philadelphia chromosome-positive acute lymphoblastic leukaemia (ph+ALL). This case report, accompanied by a comprehensive literature review, highlights the diagnostic challenges and treatment complexities encountered in the management of such rare manifestations. Moreover, the identification of a novel mutation in the LYST gene adds a unique genetic perspective to the understanding of HLH pathogenesis, potentially opening avenues for further research in this area.

Background: Haemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS) has a potentially high mortality rate. Anakinra, an interleukin‐1 receptor antagonist, is now recommended early in HLH/MAS, with intravenous (IV) use proposed in critically unwell patients. This systematic review establishes the literature relating to IV anakinra in secondary HLH/MAS (sHLH/MAS). Methods: We screened Embase, PubMed, and Medline, including all reports of IV anakinra for HLH or MAS. We extracted age, HLH/MAS trigger, continuous infusion or bolus dosing, and survival. Results: Twenty‐nine case reports/series identified 87 patients (median age 22 years, range 22 months to 84 years), all with sHLH. Amongst identifiable triggers, 43% were systemic infection, 33% rheumatological, 9% oncological. Children had predominantly a rheumatological trigger (48%), whilst adults were more commonly infection‐driven (50%). Overall, rheumatologically triggered disease showed greater survival (83.3%), particularly compared with oncological triggers (42.9%). Children had a greater survival, particularly under 10 years (83%, vs. adults, 63%). Conclusions: Despite IV anakinra recipients likely to be critically unwell, this cohort had similar disease triggers and survival compared to large historical cohorts, and enhances awareness of age and trigger‐specific survival patterns. IV anakinra had a wide therapeutic dosing range and tolerability, regardless of trigger, demonstrating substantial utility in severe sHLH/MAS. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) that occurs concomitantly with leukaemia can be initially missed due to overlapping clinical features. In a series of three cases, Tanabe and colleagues illustrate the need for prompt recognition of HLH and institution of HLH‐directed therapy to prevent hyperinflammation‐mediated multi‐organ damage and death.Commentary on: Tanabe et al. Paediatric acute lymphoblastic leukaemia‐associated haemophagocytic lymphohistiocytosis develops during prednisolone prephase. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19755. [ABSTRACT FROM AUTHOR]

Summary: Background: Haemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening syndrome characterized by an excessive inflammatory response. Limited data exist on adult HLH. Methods: In this national, retrospective cohort study, we analysed data from the US National Inpatient Sample database collected between October 1, 2006 and December 31, 2019. Using the International Classification of Diseases (ICD) codes, we identified all adult patients who were admitted non-electively with the diagnosis of HLH. We described demographic characteristics, triggers, and associated conditions. Trends of diagnosis, treatment, and in-hospital mortality were analysed using joinpoint models. In-hospital mortality rates were compared using multivariable logistic regression models that adjusted for demographic characteristics and associated conditions. Finally, we described resource utilization outcomes including cost of hospitalization and length of stay. Findings: We identified 16,136 non-elective adult HLH admissions. The population pyramid showed a bimodal distribution, with peaks in young adults (16–30 years) and older adults (56–70 years). Joinpoint regression analysis revealed a significant increase in HLH incidence per 100,000 admissions over the study period (Average Annual Percent Change [APC] = 25.3%, p

Objectives: Epstein–Barr virus (EBV) is a common cause of secondary haemophagocytic lymphohistiocytosis (HLH). While B cells are reservoirs for EBV, infection within T cells and NK cells in this disease can be difficult to treat. Methods: A 19‐year‐old female presented with a 6‐week history of coryzal symptoms on a background of Crohn's disease. On examination, she was febrile and tachycardic with mild tonsillar enlargement and splenomegaly. New trilineage cytopenias and elevation in liver enzymes were detected, with acute EBV subsequently confirmed on whole blood PCR. A diagnosis of EBV‐associated HLH was supported further with elevated serum ferritin, triglycerides and soluble CD25, low fibrinogen and the presence of haemophagocytosis in the bone marrow. Results: Corticosteroids, IVIG and rituximab were given, and anakinra was subsequently added due to ongoing fevers. EBV infection was then demonstrated within CD8+ T cells on EBER Flow‐FISH assay. Ruxolitinib was commenced and her fevers abated on day 5, with improvement in other HLH parameters. She was discharged after a 39‐day hospital admission. To date, she has remained in remission of HLH, despite developing COVID‐19 infection during the convalescence phase of HLH. Conclusion: EBV viraemia requires adequate treatment to control EBV‐associated HLH as rituximab may be insufficient, and corticosteroid resistance can result in continued EBV infection in CD8+ T cells. This entity is known as T‐cell‐EBV‐HLH. Ruxolitinib is a novel treatment strategy in this specific context and has several advantages, including inhibition of corticosteroid resistance to promote apoptosis of EBV‐infected T cells. [ABSTRACT FROM AUTHOR]

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare clinical syndrome with a high mortality rate. There is no biomarker to predict the early therapeutic response. Objective: Our study explores the significance of serum ferritin in predicting the response of induction therapy. Methods: We retrospectively analyzed the clinical data of 102 adult patients with HLH admitted to our hospital. These patients received HLH-94 regimen for induction therapy. The patients were divided into remission group and non-remission group according to the response of induction therapy. Results: Ferritin values between 1–4 weeks post induction were predictive of remission (p

Disseminated toxoplasmosis associated with haemophagocytic lymphohistiocytosis (DT-HLH) is rare and difficult to diagnose compared to disseminated toxoplasmosis or HLH presenting alone. Because of the limited number of reported cases, the clinical characteristics and outcomes of DT-HLH are unknown. We report a case of DT-HLH in a human immunodeficiency virus (HIV)-infected patient who was successfully treated with early anti-toxoplasmic therapy and performed a comprehensive literature review. A 33-year-old Cameroonian woman was transferred to our hospital owing to HIV infection and encephalitis. Although she developed HLH, bone marrow biopsy did not reveal the cause. She was diagnosed as having DT-HLH via polymerase chain reaction testing of bone marrow biopsy tissue, blood, and cerebrospinal fluid. DT-HLH improved within the initial two weeks of treatment for toxoplasmosis (sulfamethoxazole-trimethoprim, trimethoprim 10 mg/kg/day and clindamycin 1,800 mg/day) before the introduction of antiretroviral therapy. To our knowledge, only eight cases of DT-HLH have been previously reported in the literature. Most patients died within three weeks of hospitalisation and were diagnosed by autopsy. Conversely, patients diagnosed antemortem were all treated and survived, including the currently reported patient. DT-HLH can lead to poor prognosis without early and proper treatment. Clinicians should consider toxoplasmosis in the differential diagnosis of HLH.

Congenital cytomegalovirus (CMV) infection is rampant viral disease, one of the commonest non-genetic cause for neurodevelopmental delay which is often under diagnosed. Leukemoid reaction, Hemophagocytic Lymphohistiocytosis (HLH) and autoimmune cytopenias are rare hematological manifestations of CMV infection. There is paucity of literature regarding hematological manifestation in CMV infection. Here we present four cases of CMV infection with different hematological findings where early diagnosis and prompt intervention resulted in good outcome.

Background: Haemophagocytic lymphohistiocytosis (HLH) is a rare and potentially life-threatening systemic hyperinflammatory disease, which can have several aetiologies. Clinical case: a 48-year-old woman affected by a transfusion-dependent β-thalassemia was hospitalized in our haematology unit presenting with intermittent fever, haepatosplenomegaly and pancytopenia, which developed a few days after the booster dose of anti-SARS-CoV-2 mRNA vaccine. The investigations performed during hospitalization led to a diagnosis of HLH and steroid therapy where IV dexamethasone was initiated and provided benefits. Conclusions: the severity of HLH mandates early treatment, but the management of patients with post-vaccine HLH is still challenging and requires further study. No cases of HLH in patients with thalassemia were previously described.

Background: Many syndromes are associated with exaggerated inflammation. Children with hyperinflammatory syndromes often present with vague and non-specific symptoms that pose diagnostic and management challenges. The recent literature seems biased towards referring these syndromes only to the multisystem inflammatory syndrome in children (MIS-C) that is associated with COVID-19. The purpose of this paper is to provide an updated narrative review on the pathophysiology, manifestations and management approaches for common hyperinflammatory syndromes. Methods: An extensive PubMed search of all publications in the English literature was performed with Clinical Queries for various hyperinflammatory syndromes and conditions using the undermentioned Medical Subject Headings: “hyperinflammation”, “hyperinflammatory syndromes”, “sepsis syndrome”, “severe inflammatory response syndrome” and “acute respiratory distress syndrome”. Categories were limited to reviews and clinical trials for the age range from birth to 18 years. Results: The criteria, presentation and management of these hyperinflammatory syndromes are described. Hyperinflammatory syndromes refer to a basket of inflammatory syndromes often associated with multisystem involvement and aberrant cytokine release and should be differentiated from autoinflammatory, autoimmune and hyperimmune syndromes. The major subtypes of hyperinflammatory syndromes, including macrophage activation syndrome, haemophagocytic lymphohistiocytosis, cytokine release syndrome and cytokine storm syndrome, are described. MIS-C associated with SARS-CoV-2 represents the latest addition. It must be understood that the syndrome is not exclusive to COVID-19 but could be caused by various viral infections. Early recognition, prompt and proactive treatment can reduce potential complications and improve outcomes and survival rates in paediatric patients. Anti-inflammatory medications for the management of these syndromes are described. Conclusion: The incidence of these hyperinflammatory conditions is generally low in comparison to other disease conditions. Except for paediatric inflammatory multisystem syndrome/MIS-C, the mortality is high and the hospital stay is prolonged in affected patients. Acute and critical care physicians must be aware of these conditions and their initial management. Corticosteroids are often used in the initial phrase but various disease-specific drugs and biologics are needed in subsequent management and expert management of these often-difficult conditions is crucial.

Key message Hemophagocytic lymphohistiocytosis (HLH) has been reported as a rare complication of immune checkpoint inhibitors (ICI); however, ICI‐related HLH is a life‐threatening and comparatively late adverse event. Early diagnosis is critical, and it should be included in the differential diagnosis especially in patients with cytopenia with fever and hyperferritinaemia.

Haemophagocytic lymphohistiocytosis (HLH) is a cytokine-driven inflammatory syndrome caused by uncontrolled hypersecretion of inflammatory cytokines. Conventional first-line treatment for HLH included HLH-94 and HLH-2004 regimens. However, quite a few patients do not respond to treatment or cannot tolerate intensive chemotherapy. We reported two cases of HLH, one caused by natural killer (NK)/T-cell lymphoma and another associated with missense variants in the perforin 1 gene. They both received the ruxolitinib plus dexamethasone protocol and had a rapid response to treatment without obvious adverse effects. Our report indicates that treatment with ruxolitinib plus dexamethasone might be a potential option for HLH, and clinical trials warrant further investigation. In addition, the detection of HLH-related genes is necessary for the identification of late-onset familial HLH in certain settings.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), also known as autoimmune polyglandular syndrome type 1 (APS-1) is a rare autosomal recessive inborn error of immunity (IEI), which is accompanied by immune dysregulation. Hypoparathyroidism, adrenocortical failure and candidiasis are its typical manifestations. Here we report about recurrent COVID-19 in a 3-year-old boy with APECED, who developed retinopathy with macular atrophy and autoimmune hepatitis after the first episode of SARS-CoV-2 infection. Primary Epstein-Barr virus infection and a new episode of SARS-CoV-2 infection with COVID pneumonia triggered the development of severe hyperinflammation with signs of hemophagocytic lymphohistiocytosis (HLH): progressive cytopenia (thrombocytopenia, anemia, lymphopenia), hypoproteinemia, hypoalbuminemia, high levels of liver enzymes, hyperferritinemia, increased triglycerides levels; and coagulopathy with a low level of fibrinogen. Treatment with corticosteroids and intravenous immunoglobulins did not lead to a significant improvement. The progression of HLH and COVID-pneumonia resulted in a fatal outcome. The rarity and varied presentation of the HLH symptoms led to diagnostic difficulties and diagnosis delay. HLH should be suspected in a patient with immune dysregulation and impaired viral response. Treatment of infection-HLH is a major challenge due to the difficulties in balancing immunosuppression and management of underlying/triggering infection.

Secondary haemophagocytic lymphohistiocytosis (sHLH) is a life-threatening disorder described in the setting of infections, neoplastic and immune dysregulations. Recently, sHLH has been reported following chimeric antigen receptor T-cell (CAR-T) therapy as a severe manifestation of cytokine release syndrome (CRS) which generally occurs during the early phase after a CAR-T infusion. CAR-T therapy for both relapse/refractory acute lymphoblastic B-cell leukaemia (B-ALL) and non-Hodgkin lymphoma, (diffuse large B-cell lymphoma (DLBCL) and primary mediastinal B-cell lymphoma (PMBCL)), has been approved by FDA and EMA as a third line treatment. CRS is on-target off-tumour side effect of CAR-T therapy which results in an acute state of hyperinflammation due to both tumour lysis and the proliferation of CAR-T cells. Its clinical presentation has a wide spectrum of severity, in the worst case it could rapidly lead to a multiorgan failure and progress to a fatal sHLH. Here, we present a late occurrence of sHLH after CAR-T treatment. [ABSTRACT FROM AUTHOR]

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare clinical syndrome with a high mortality rate. There is no biomarker to predict the early therapeutic response. Objective: Our study explores the significance of serum ferritin in predicting the response of induction therapy. Methods: We retrospectively analyzed the clinical data of 102 adult patients with HLH admitted to our hospital. These patients received HLH-94 regimen for induction therapy. The patients were divided into remission group and non-remission group according to the response of induction therapy. Results: Ferritin values between 1–4 weeks post induction were predictive of remission (p<.05), which were higher in the non-remission group than in the remission group. Ferritin obtained 2 weeks post-induction had the highest ROC for predicting remission, with a cut-off value of 1188.5 µg/L. And patients with ferritin lower than 1188.5 µg/L had better response of induction therapy. Conclusion: Our study suggests that serum ferritin is a good indicator to predict the efficacy of induction therapy for adult HLH. Serum ferritin is a good indicator for predicting the efficacy of adult HLH induction therapy. Serum ferritin two weeks after treatment may be a better indicator to judge the early curative effect. Serum ferritin after treatment also had a predictive significance for the survival of HLH. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) is an underrecognized hyperinflammatory condition with a high mortality, characterized by inappropriate survival of histiocytes and cytotoxic T cells (CTLs), leading to a cytokine storm, haemophagocytosis and multi-organ damage (1). The currently accepted terminology includes two forms of HLH: the primary or familial HLH (fHLH) and the secondary HLH (sHLH) (2). The sHLH associated with rheumatic conditions is known as macrophage activation syndrome (MAS). MAS can develop at any time during the evolution of the rheumatic diseases: at the beginning, during flare of the disease or during intercurrent infections – mostly with viral trigger. We present a case of MAS in an patient with adult-onset Still Disease. It is of great importance to be recognized in early stages, because if promptly treated it might respond well to combination therapy of glucocorticoids and IL1- blockers.

Abstract Objectives Epstein–Barr virus (EBV) is a common cause of secondary haemophagocytic lymphohistiocytosis (HLH). While B cells are reservoirs for EBV, infection within T cells and NK cells in this disease can be difficult to treat. Methods A 19‐year‐old female presented with a 6‐week history of coryzal symptoms on a background of Crohn's disease. On examination, she was febrile and tachycardic with mild tonsillar enlargement and splenomegaly. New trilineage cytopenias and elevation in liver enzymes were detected, with acute EBV subsequently confirmed on whole blood PCR. A diagnosis of EBV‐associated HLH was supported further with elevated serum ferritin, triglycerides and soluble CD25, low fibrinogen and the presence of haemophagocytosis in the bone marrow. Results Corticosteroids, IVIG and rituximab were given, and anakinra was subsequently added due to ongoing fevers. EBV infection was then demonstrated within CD8+ T cells on EBER Flow‐FISH assay. Ruxolitinib was commenced and her fevers abated on day 5, with improvement in other HLH parameters. She was discharged after a 39‐day hospital admission. To date, she has remained in remission of HLH, despite developing COVID‐19 infection during the convalescence phase of HLH. Conclusion EBV viraemia requires adequate treatment to control EBV‐associated HLH as rituximab may be insufficient, and corticosteroid resistance can result in continued EBV infection in CD8+ T cells. This entity is known as T‐cell‐EBV‐HLH. Ruxolitinib is a novel treatment strategy in this specific context and has several advantages, including inhibition of corticosteroid resistance to promote apoptosis of EBV‐infected T cells.

Scrub typhus is a natural foci disease caused by the bacteria Orientia tsutsugamushi. Symptoms of the disease range from fever to severe multiple organ dysfunction. The diagnosis is based on clinical signs and antibody serological tests, which has poor sensitivity and specificity. Scrub typhus is rarely associated with multiple organ dysfunction syndrome (MODS) and haemophagocytic lymphohistiocytosis (HLH). In this paper, we report a 17-year-old Asian male who was characterized with a persistent fever without eschar. He was diagnosed with scrub typhus using metagenomic next-generation sequencing (mNGS) of the blood after negative of routine examinations. The patient was progressed to HLH and MODS but had a good recovery following anti-rickettsial therapy, dexamethasone, and advanced life support. Besides, we present a brief overview of the literature about scrub typhus and associated complications.

• DT-HLH occurs rarely and is difficult to diagnose. • The clinical characteristics and outcomes of DT-HLH are unknown. • We report a case of DT-HLH in an HIV patient treated with anti-toxoplasmic therapy. • We also report a comprehensive literature review. • Clinicians should consider toxoplasmosis in the differential diagnosis of HLH. Disseminated toxoplasmosis associated with haemophagocytic lymphohistiocytosis (DT-HLH) is rare and difficult to diagnose compared to disseminated toxoplasmosis or HLH presenting alone. Because of the limited number of reported cases, the clinical characteristics and outcomes of DT-HLH are unknown. We report a case of DT-HLH in a human immunodeficiency virus (HIV)-infected patient who was successfully treated with early anti-toxoplasmic therapy and performed a comprehensive literature review. A 33-year-old Cameroonian woman was transferred to our hospital owing to HIV infection and encephalitis. Although she developed HLH, bone marrow biopsy did not reveal the cause. She was diagnosed as having DT-HLH via polymerase chain reaction testing of bone marrow biopsy tissue, blood, and cerebrospinal fluid. DT-HLH improved within the initial two weeks of treatment for toxoplasmosis (sulfamethoxazole-trimethoprim, trimethoprim 10 mg/kg/day and clindamycin 1,800 mg/day) before the introduction of antiretroviral therapy. To our knowledge, only eight cases of DT-HLH have been previously reported in the literature. Most patients died within three weeks of hospitalisation and were diagnosed by autopsy. Conversely, patients diagnosed antemortem were all treated and survived, including the currently reported patient. DT-HLH can lead to poor prognosis without early and proper treatment. Clinicians should consider toxoplasmosis in the differential diagnosis of HLH. [ABSTRACT FROM AUTHOR]

Background: Haemophagocytic lymphohistiocytosis (HLH) is a rare and potentially life-threatening systemic hyperinflammatory disease, which can have several aetiologies. Clinical case: a 48-year-old woman affected by a transfusion-dependent β-thalassemia was hospitalized in our haematology unit presenting with intermittent fever, haepatosplenomegaly and pancytopenia, which developed a few days after the booster dose of anti-SARS-CoV-2 mRNA vaccine. The investigations performed during hospitalization led to a diagnosis of HLH and steroid therapy where IV dexamethasone was initiated and provided benefits. Conclusions: the severity of HLH mandates early treatment, but the management of patients with post-vaccine HLH is still challenging and requires further study. No cases of HLH in patients with thalassemia were previously described. [ABSTRACT FROM AUTHOR]

What is known and objective: Lamotrigine is currently known to be related to haemophagocytic lymphohistiocytosis (HLH). Knowledge regarding the association between HLH and lamotrigine is mainly based on case reports. The purpose of this study was to evaluate the clinical characteristics of lamotrigine‐induced HLH. Methods: We collected literature from 1994 to 31 August 2020 in Chinese and English on HLH induced by lamotrigine for retrospective analysis. Results and discussion: A total of 17 patients (12 men and 5 women) from 15 studies were included, with a median age of 29 years old (range 4–47). Symptoms of lamotrigine‐induced HLH were reported to have occurred within 6–24 days following treatment initiation. Six cases reported doses that ranged from 25 mg every other day to 800 mg once daily. The major clinical features of lamotrigine‐induced HLH are fever, cytopenia, rash and hyperferritinaemia. Bone marrow showed haemophagocytosis. Fifteen patients improved with drug discontinuation, and 2 patients eventually died. What is new and conclusion: Hemophagocytic lymphohistiocytosis is a potentially serious adverse reaction to lamotrigine (LTG). Patients should be informed that if they experience any symptoms of HLH while taking lamotrigine, they should immediately seek medical attention. [ABSTRACT FROM AUTHOR]

Tuberculosis-associated haemophagocytic lymphohistiocytosis (HLH) is rare in paediatrics and can be fatal if not recognised and treated on time. A 3-month-old infant with tuberculosis and HLH is described. He was successfully treated with anti-tuberculous therapy (ATT) which comprised isoniazid, rifampicin, pyrazinamide, ethambutol, streptomycin and dexamethasone (10 mg/m2/day). On Day 28 of therapy, he developed a paradoxical upgrading reaction to ATT for which he was again treated with (oral) corticosteroids for 4 weeks. He recovered successfully and is now completely well and asymptomatic. To the best of our knowledge, this is the first case of a child having a paradoxical upgrading reaction following treatment for TB-HLH. Abbreviations ATT: anti-tuberculous therapy; CB-NAAT: cartridge-based nucleic acid amplification test; CECT: contrast-enhanced computed tomography; HLH: haemophagocytic lymphohistiocytosis; NK: natural killer, PUR: paradoxical upgrading reaction; sHLH: secondary HLH. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) is a complex, often under‐recognised hyperinflammatory immune dysregulation syndrome arising in a diverse range of clinical scenarios and conditions. The accurate and timely diagnosis of HLH is crucial for patient survival, and usually requires a high level of clinical suspicion. The histological corollary to clinical HLH—haemophagocytosis—is neither necessary nor sufficient for the diagnosis of HLH, as it may be seen in a variety of reactive conditions and may be absent in true HLH. Nevertheless, the finding of haemophagocytosis in specific clinical situations should prompt consideration of HLH and further testing to exclude the condition. Although haemophagocytosis is traditionally described in bone marrow, identification of it in other tissues, including lymphoid, splenic, liver or neural tissue, can contribute importantly to the overall recognition of HLH. In this review we discuss the underlying pathophysiology and aetiologies of HLH, and the morphological aspects of haemophagocytosis and its associated histological findings in different tissues, and give a brief overview of diagnostic criteria and clinical evaluation. [ABSTRACT FROM AUTHOR]

Objective: An association exists between immune checkpoint inhibitors and hemophagocytic lymphohistiocytosis (HLH). Therefore, the main objective of this study was to collect data on this rare but potentially life-threatening immune-related adverse reaction to identify the medications that cause it, the clinical characteristics, and effective treatments., Methods: Literature in English and Chinese on immune checkpoint inhibitors causing HLH published from August 2014 to March 2024 was analyzed. Immune checkpoint inhibitors, immunotherapy, anti-PD-1, PD-L1 inhibitors, HLH, hemophagocytic lymphohistiocytosis, hemophagocytic syndrome keywords were used to find the literature on China Knowledge Network, Wanfang, PubMed and Emabase Databases., Results and Discussion: Twenty-four studies were included, with a total of 27 patients (18 males and 9 females) with a mean age of 58 years (range 26-86). The mean time to the onset of symptoms was 10.3 weeks (7 days-14 months). The main clinical characteristics were fever, cytopenia, splenomegaly, methemoglobinemia, hypofibrinogenemia, and bone marrow biopsy showed phagocytosis. Twenty-two patients improved after the treatment with steroids, cytokine blocking therapy and symptomatic treatment, four patients died, and one patient was not described., Conclusion: HLH should be not underestimated as a potentially serious adverse effect of immune checkpoint inhibitors since appropriate treatments may save the life of patients.

Haemophagocytic lymphohistiocytosis (HLH) is a rare disease but potentially life threatening clinical syndrome. It is caused by a multisystemic hyperinflammatory process secondary to severe hypercytokinemia with excessive and uncontrolled activation of the immune response. We report a case of familial HLH with no apparent causes in 6 months-old Malay girl presented with recurrent fever associated with severe anaemia and bleeding tendency requiring extensive treatment but refractory to the treatment which lead to mortality due to neutropenic sepsis indicating of poor prognosis of this disease. This familial type of HLH should be suspected in all children after excluding all the secondary causes with collective laboratory features and requiring extensive management as it associated with high mortality. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) is an underrecognized hyperinflammatory condition with a high mortality, characterized by inappropriate survival of histiocytes and cytotoxic T cells (CTLs), leading to a cytokine storm, haemophagocytosis and multi-organ damage (1). The currently accepted terminology includes two forms of HLH: the primary or familial HLH (fHLH) and the secondary HLH (sHLH) (2). The sHLH associated with rheumatic conditions is known as macrophage activation syndrome (MAS). MAS can develop at any time during the evolution of the rheumatic diseases: at the beginning, during flare of the disease or during intercurrent infections – mostly with viral trigger. We present a case of MAS in an patient with adult-onset Still Disease. It is of great importance to be recognized in early stages, because if promptly treated it might respond well to combination therapy of glucocorticoids and IL1- blockers. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) or haemophagocytic syndrome is a rare but life-threatening syndrome of excessive immune activation with nonspecific clinical presentation. HLH is one of the complications in dengue infection. A 69-year-old lady was treated for severe dengue with multi-organ dysfunction with superimposed pneumonia, requiring mechanical ventilation. However, persistent cytopenia despite blood transfusion without evidence of haemorrhage raised the suspicion of HLH. Further blood investigations revealed hypertriglyceridaemia, hypofibrinogenaemia and hyperferritinaemia. Bone marrow aspiration showed haemophagocytosis. Patient fulfilled the diagnostic criteria for HLH by HLH-2004 trial. Her HScore is 281, with the probability of having HLH is 99.9%. Patient's condition improved after administration of intravenous immunoglobulin (IVIG) and intravenous dexamethasone in tapering doses. Early specific treatment of HLH with IVIG and/or corticosteroid is important but diagnosis is usually delayed due to nonspecific clinical findings and laboratory results. High index of suspicion with the aid of diagnostic criteria by HLH-2004 trial and HScore is helpful to recognise this syndrome. [ABSTRACT FROM AUTHOR]

Haemophagocytic lymphohistiocytosis (HLH) represents a life‐threatening hyperinflammatory syndrome. Familial studies have established autosomal and X‐linked recessive causes of HLH, highlighting a pivotal role for lymphocyte cytotoxicity in the control of certain virus infections and immunoregulation. Recently, a more complex etiological framework has emerged, linking HLH predisposition to variants in genes required for metabolism or immunity to intracellular pathogens. We review genetic predisposition to HLH and discuss how molecular insights have provided fundamental knowledge of the immune system as well as detailed pathophysiological understanding of hyperinflammatory diseases, highlighting new treatment strategies. [ABSTRACT FROM AUTHOR]

During COVID‐19 infection, reduced function of natural killer (NK) cells can lead to both compromised viral clearance and dysregulation of the immune response. Such dysregulation leads to overproduction of cytokines, a raised neutrophil/lymphocyte ratio and monocytosis. This in turn increases IL‐6 expression, which promotes scar and thrombus formation. Excess IL‐6 also leads to a further reduction in NK function through downregulation of perforin expression, therefore forming a pathogenic auto‐inflammatory feedback loop. The perforin/granzyme system of cytotoxicity is the main mechanism through which NK cells and cytotoxic T lymphocytes eliminate virally infected host cells, as well as being central to their role in regulating immune responses to microbial infection. Here, we present epidemiological evidence suggesting an association between perforin expression and resistance to COVID‐19. In addition, we outline the manner in which a pathogenic auto‐inflammatory feedback loop could operate and the relationship of this loop to genes associated with severe COVID‐19. Such an auto‐inflammatory loop may be amenable to synergistic multimodal therapy. [ABSTRACT FROM AUTHOR]

Rationale: Haemophagocytic lymphohistiocytosis is a rare complication of malaria, which is often misdiagnosed. Patient concerns: A 30-year-old male was admitted to our department for persistent fever, which began after returning from a stay in Guinea-Conakry. The laboratory investigations revealed a pancytopenia and an elevated C-reactive protein. Peripheral smear examination showed Plasmodium falciparum, therefore confirming the diagnosis of malaria. The laboratory tests showed a worsening pancytopenia. Bone marrow aspiration and biopsy revealed images of hemophagocytosis. Diagnosis: The diagnosis of haemophagocytic lymphohistiocytosis complicating malaria infection was established. Interventions: The patient was treated with artemether-lumefantrine. No immunosuppressant treatment was delivered to the patient. He received antipyretic and antimalarial treatment only. Outcomes and lessons: We report a case of haemophagocytic lymphohistiocytosis trigged by malaria infection and we review all reported cases secondary to Plasmodium falciparum malaria by searching PubMed publications till October 2019. Haemophagocytic lymphohistiocytos secondary to malaria should be suspected even in non-severe cases of malaria.

Objective: To assess current treatment in macrophage activation syndrome (MAS) worldwide and to highlight any areas of major heterogeneity of practice., Methods: A systematic literature search was performed in both Embase and PubMed databases. Paper screening was done by two independent teams based on agreed criteria. Data extraction was standardized following the PICO framework. A panel of experts assessed paper validity, using the Joanna Briggs Institute appraisal tools and category of evidence (CoE) according to EULAR procedure., Results: Fifty-seven papers were finally included (80% retrospective case-series), describing 1148 patients with MAS: 889 systemic juvenile idiopathic arthritis (sJIA), 137 systemic lupus erythematosus (SLE), 69 Kawasaki disease (KD) and 53 other rheumatologic conditions. Fourteen and 11 studies specified data on MAS associated to SLE and KD, respectively. All papers mentioned glucocorticoids (GCs), mostly methylprednisolone and prednisolone (90%); dexamethasone was used in 7% of patients. Ciclosporin was reported in a wide range of patients according to different cohorts. Anakinra was used in 179 MAS patients, with a favourable outcome in 83% of sJIA-MAS. Etoposide was described by 11 studies, mainly as part of HLH-94/04 protocol. Emapalumab was the only medication tested in a clinical trial in 14 sJIA-MAS, with 93% of MAS remission. Ruxolitinib was the most reported JAK-inhibitor in MAS., Conclusion: High-dose GCs together with IL-1 and IFNγ inhibitors have shown efficacy in MAS, especially in sJIA-associated MAS. However, global level of evidence on MAS treatment, especially in other conditions, is still poor and requires standardized studies to be confirmed., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)