How to Treat Involvement of the Central Nervous System in Hemophagocytic Lymphohistiocytosis?

Methylmalonic acidemia with recurrent hemophagocytic lymphohistiocytosis: a case report and review of the literature

BACKGROUND

Methylmalonic acidemia is a rare autosomal recessive disorder of propionate catabolism characterized by the accumulation of propionic acid and methylmalonic acid caused by methylmalonyl-CoA mutase deficiency. Clinical presentations range from acute deterioration in the neonatal period to later onset with a heterogeneous clinical course. Metabolite accumulation results in systemic involvement, affecting the nervous, gastrointestinal, and renal system functions and causing cardiomyopathy. Bone marrow dysfunction manifesting as neutropenia and anemia is a common hematological finding. Although rare, three cases of secondary hemophagocytosis were documented.

CASE PRESENTATION

An 18-year-old male patient diagnosed with methylmalonic acidemia presented with vomiting and altered mental status. He had a medical history of presumably hemophagocytic lymphohistiocytosis (HLH) at the age of 17 months. Physical examination, laboratory tests, and bone marrow aspiration results met the HLH-2004 diagnostic criteria, confirming a recurrent HLH. Although he recovered after intensive treatment, his cognitive function declined. Retrospective analysis revealed higher serum levels of ferritin during acute decompensations compared with nonattack periods. Correlation analysis revealed a strong relationship between serum ferritin and propionylcarnitine, one of the major propionyl-CoA-derived metabolites.

CONCLUSIONS

HLH is a rare and underrecognized hematologic emergency in methylmalonic acidemia, and its early diagnosis and treatment are critical. Serum ferritin may be a useful clinical biomarker in the diagnosis of HLH-associated attacks in methylmalonic acidemia.

Isolated central nervous system haemophagocytic lymphohistiocytosis with PRF1 gene mutation presenting as fever of unknown origin

Central nervous system (CNS) manifestations are seen in two-thirds cases of familial haemophagocytic lymphohistiocytosis (HLH). Isolated CNS-HLH is described as a rare entity characterised by isolated neuroinflammation without fulfilling diagnostic criteria for evidence of systemic inflammation in mutation-proven familial HLH due to additional genetic modifiers. We describe one such female preschooler who presented to us with the fever of unknown origin spanning over a year and was a diagnostic dilemma. Only two out of the available seven criteria were fulfilled for systemic HLH in the index child. A neuroimaging study done as part of the investigation for seizure led to suspicion of CNS-HLH, and the final diagnosis was established by whole-exome sequencing, which revealed PRF1 mutation. Knowledge about isolated CNS-HLH will help keep it a differential diagnosis in cases where cerebrospinal fluid and neuroimaging findings may suggest a neuroinflammatory disorder. It may lead to early diagnosis and prompt therapy, thereby preventing long-term neurological sequelae.

Hemophagocytic lymphohistiocytosis caused by multiple infections during primary chemotherapy for pediatric acute lymphoblastic leukemia: a case report

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory disorder that occurs as a consequence of immune dysregulation. HLH can be primary (familial or non-familial) or secondary to infection, autoimmune disease or malignancy. Malignancy-associated HLH is often accompanied by hematologic and lymphoid neoplasms. This report describes the case of a 3-year-old girl with an initial diagnosis of acute lymphoblastic leukemia who subsequently developed HLH during primary chemotherapy. She was admitted with a pulmonary infection, and initial blood tests showed thrombocytopenia and anemia. Whole-exome sequencing of gene and whole transcriptome RNA sequencing data indicated mutations of UNC13D. The hospital course was complicated by multiple infections, altered mental status and acute respiratory distress syndrome. HLH secondary to multiple infections that achieved remission following targeted therapy with ruxolitinib, in conjunction with corticosteroids and other complementary treatments. This report provides a synopsis of the diagnostic and treatment procedures implemented in this case.

Comprehensive mapping of immune perturbations associated with secondary hemophagocytic lymphohistiocytosis

Secondary hemophagocytic lymphohistiocytosis (sHLH) is a hyperinflammatory syndrome characterized by immune disorders. It is imperative to elucidate the immunophenotypic panorama and the interactions among these cells in patients. Human peripheral blood mononuclear cells were collected from healthy donors and sHLH patients and tested using multicolor flow cytometry. We used FlowSOM to explore and visualize the immunophenotypic characteristics of sHLH. By demonstrating the phenotypes of immune cells, we discovered that sHLH patients had significantly higher levels of CD56+ monocytes, higher levels of myeloid-derived suppressor cells, low-density neutrophil-to-T cell ratio, and higher heterogeneous T cell activation than healthy donors. However, natural killer cell cytotoxicity and function were impaired. We then assessed the correlations among 30 immune cell types and evaluated metabolic analysis. Our findings demonstrated polymorphonuclear myeloid-derived suppressor cells, CD56+ monocytes, and neutrophil-to-T cell ratio were elevated abnormally in sHLH patients, which may indicate an association with immune overactivation and inflammatory response. We are expected to confirm that they are involved in the occurrence of the disease through further in-depth research.

Hemophagocytic lymphohistiocytosis in an adult patient with super-refractory status epilepticus

This case report presents a 38-year-old male patient who, after a febrile infection, developed super-refractory status epilepticus and multiorgan failure, and died in 2 weeks despite the best possible intensive care. Autopsy revealed findings suggestive of hemophagocytic lymphohistiocytosis (HLH). This case shows that a rare immunological cause such as HLH may cause febrile infection-related epilepsy syndrome (FIRES), and complications of intensive care can mask the physiological and laboratory changes in HLH. PLAIN LANGUAGE SUMMARY: This case report presents a 38-year-old man who, after a febrile infection, developed intractable epileptic activity requiring intensive care treatment. During the intensive care, the patient showed signs of multiple organ damage and died in 2 weeks despite the best possible treatment. Autopsy revealed findings suggestive of hemophagocytic lymphohistiocytosis (HLH), which is a rare immune system regulation disorder leading to persistent inflammatory state and organ damages. This case shows that an immunological disorder like HLH may underlie treatment resistant fever-related epileptic seizures.

Biomarkers in Pediatric Hemophagocytic Lymphohistiocytosis With Central Nervous System Involvement: A Cohort Study

BACKGROUND

The aim of this study was to analyze the clinical significance of cerebrospinal fluid (CSF) cytokines in hemophagocytic lymphohistiocytosis associated with central nervous system (CNS-HLH).

METHODS

CSF cytokine levels, including interferon (IFN)-γ, soluble CD25 (sCD25), interleukin (IL)-6, IL-10, IL-18, and CXCL9 were measured at disease onset and during the treatment. Five newly diagnosed patients with demyelination disease were enrolled for comparison.

RESULTS

Sixty-five samples from 36 patients (13 in the CNS group and 23 in the non-CNS group) were detected. Levels of CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 in the CNS group were higher than those in the non-CNS group ( P =0.038, <0.001, <0.001, 0.005, and <0.001), and levels of CSF sCD25, IL-10, IL-18, and CXCL9 in the CNS group were higher than those in the demyelination group ( P =0.001, 0.008, 0.004, and 0.003). There was no significant difference in IL-6 levels among the 3 groups ( P =0.339). CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 could assist in diagnosing CNS-HLH. The diagnostic efficiency of CSF sCD25, IL-10, and CXCL9 was better, with a cutoff value of 154.64, 1.655, and 19.54 pg/mL, respectively. The area under the curve was >0.9, with sensitivity and specificity >80%. Correlation analysis suggested that in the CNS group, IFN-γ levels in CSF and serum correlated positively ( R =0.459, P =0.007), while there was no correlation between CSF CXCL9 and serum IFN-γ ( P =0.915).

CONCLUSIONS

CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 levels were significantly higher in HLH patients with CNS involvement than those without and could predict HLH patients with CNS involvement. CSF CXCL9 might be a more sensitive biomarker to CNS-HLH than IFN-γ, while CSF IL-6 does not seem to play a vital role.

Griscelli syndrome: a diagnostic challenge of a rare disease: a case report

Introduction

Griscelli syndrome (GS) is a rare autosomal recessive genetic disorder that primarily manifests as hair and skin hypopigmentation, with three types differentiated by their specific genetic defects as well as by their clinical features. Clinically, GS type 1 is characterized by early neurological alterations, while GS type 2 is characterized by immunodeficiency and could present with neurological symptoms, and type 3 is characterized by a chromosomal anomaly without a specific clinical profile besides hypopigmentation. This article details the challenges faced in the diagnosis of a patient with GS who presents with neurological symptoms followed by immunological deficits.

Case presentation

A 7-month-old female presented with complaints of developmental delay following an otitis media infection. Upon examination, she exhibited signs of psychomotor developmental regression and had pale bronze skin and silvery-gray hair, as well as hepatosplenomegaly. The examination of her hair shaft revealed a pattern consistent with GS. During her hospitalization, the patient developed an intermittent fever and signs of hemophagocytic lymphohistiocytosis (HLH). She subsequently developed recurrent seizures treated with phenytoin and Aciclovir. Shortly she succumbed to respiratory distress syndrome and multisystem failure.

Discussion

The presence of HLH confirms the type of GS. However, in some cases, the HLH criteria could not be fulfilled, presenting a diagnostic challenge.

Conclusion

The genetic examination is the only way to differentiate GS type 1 from type 2. However, when it is not available, the presence of specific symptoms and features may assist in the classification. Furthermore, treatments should be administered when GS type 2 is suspected since they have the potential to improve life quality through treating HLH, delaying and altering the neurological symptoms.

The effectiveness of the doxorubicin-etoposide-methylprednisolone regimen for adult HLH secondary to rheumatic disease

To investigate the efficacy of the doxorubicin-etoposide-methylprednisolone, DEP) regimen as an effective treatment for adult Hemophagocytic Lymphohistiocytosis secondary to rheumatic disease and analyze prognosis in these patients. Fifty-eight adult patients diagnosed with Hemophagocytic Lymphohistiocytosis secondary to rheumatic disease admitted to Beijing Friendship Hospital from 1st Jan. 2018 to 31st Dec. 2022 were retrospectively included in this study. Patients were grouped according to previous treatment. Clinical data and laboratory characteristics of patients were retrospectively analyzed. The efficacy was evaluated every 2 weeks after initiating the first course of the DEP regimen and until the last inpatient or 31st Dec. 2023. 26 patients were included in Group A and 32 patients were included in Group B due to the previous treatment. After the first course of the DEP regimen, the overall response rate of all patients was 82.8%, with 13.8% in complete response and 69% in partial response. There was no significant statistical objective response rate between the two groups after the DEP regimen, except at 2-week. Serum ferritin, sCD25, ALT, AST, and DBIL concentrations were significantly lower at 2, 4 and 6-week than pre-treatment (P < 0.05). The overall mortality rate is 20.7% (12/58). Importantly, advanced age, initial level of HB and PLT, and central nervous system (CNS) involvement were independent poor risk factors affecting OS in bivariate analysis. The DEP regimen is effective for adult HLH secondary rheumatic disease with a high overall rate and accepted side effects.

Autoimmune encephalitis followed by hemophagocytic lymph histiocytosis: a case report

Objective

This study aims to report three cases of autoimmune encephalitis followed by hemophagocytic lymphohistiocytosis.

Methods

Data of relevant patients treated between 2019 and 2022 were retrospectively collected from the Department of Neurology at the Second Affiliated Hospital of Guangzhou Medical University.

Results

The age at onset of the three patients was 37, 63, and 36 years, respectively. All three patients were female and presented with cognitive dysfunction and seizures. Behavioral and psychological symptoms were also observed in two cases. All patients were positive for autoantibodies in both the cerebrospinal fluid and serum, while two showed multiple abnormal brain signals on magnetic resonance imaging. All patients exhibited hypocytosis and elevated soluble CD25 and serum ferritin levels. The final diagnoses in two cases were lymphomas, while the remaining case without tumors suffered from a severe infection. All patients received immunotherapy, and the two with lymphoma received anti-tumor treatment. The patient with infection died, and two patients with tumors improved after chemotherapy.

Conclusion

Autoimmune encephalitis followed by hemophagocytic lymphohistiocytosis is a rare and severe condition. Prompt attention should be paid to the decline in blood cell counts, particularly in patients who show a slight improvement after immunotherapy or have a risk of lymphoma. Screening for potential tumors and infections and early treatment may help these patients.

Allogeneic hematopoietic stem cell transplant for familial hemophagocytic lymphohistiocytosis: a case report and literature review

Objectives

This study aims to discuss the clinical manifestations and treatment of Familial hemophagocytic lymphohistiocytosis (FHL) caused by a mutation in the UNC13D gene.

Methods

A 6-year-old female child presented with unexplained febricity, splenomegaly, pancytopenia, hemophagocytic lymphohistiocytosis in bone marrow, decreased NK cell activity, soluble CD25 levels > 44000ng/ml. Genetic sequencing revealed a mutation in the UNC13D gene. Additionally, the patient experienced intermittent fever with seizures characterized by involuntary twitching of the left upper limb. Head magnetic resonance imaging (MRI) showed white matter lesions.

Results

According to the HLH-2004 diagnostic criteria revised by the International Society of Histiocytosis the patient was diagnosed with FHL. Despite receiving HLH-2004 treatment, the disease relapsed. However, after a salvage allogeneic Hematopoietic Stem Cell Transplant (HSCT), febricity, abnormal blood cells, and neurological symptoms significantly improved.

Conclusions

Prompt performance of allogeneic HSCT is crucial upon diagnosis of FHL, especially when neurological involvement is present.

Clinical Presentations, Diagnosis, and Genetic Features of Hemophagocytic Lymphohistiocytosis: A Single Institutional Experience With the Saudi Population

Background Hemophagocytic lymphohistiocytosis (HLH) is an uncommon, potentially fatal condition caused by high immune activation. The present study aimed to identify the clinical manifestations, geographic distribution, and associated pathogenic genetic mutations of HLH in Saudi Arabia. Method A retrospective cross-sectional study was conducted at King Fahad Medical City (KFMC), with a total of 59 patients diagnosed with HLH in the period between 2006 and 2018. All genetic results and clinical and biochemical data were retrieved and statistically analyzed using IBM SPSS Statistics for Windows, Version 25 (Released 2017; IBM Corp., Armonk, New York, United States). Results The results revealed that 48 patients (81.4%) had 15 pathogenic mutations of primary HLH whereas 8 (13.6%) patients had no genetic mutation. The most common variant mutation identified was c.1430C>T of the STXBP2 gene (42.4% of total patients), followed by c.1122G>A of the PRF1 gene (10.2% of patients), which demonstrated a distinctive geographic and tribal association. Patients with RAB27A mutation tend to present at an older age than the others with a median age of presentation of 5.5 months vs 2 months for patients with PRF1 mutations. No significant differences in clinical features were observed among the various groups. Conclusion This study highlights the incidence of genetic mutations among the Saudi population with HLH. The STXBP2 is the most common mutation followed by PRF1 mutations, many mutation variants are associated with a distinctive tribal and geographic association.

Navigating Complexity: A Case Study on Hemophagocytic Lymphohistiocytosis Diagnosis and Management Challenges

Hemophagocytic lymphohistiocytosis (HLH) is a severe inflammatory disorder that affects multiple organ systems and carries a high risk of mortality if untreated. Treatment typically involves immune suppression with steroids and cytotoxic drugs. This case report details the evaluation and management of an adult female presenting with atypical symptoms, aims to improve awareness and understanding of HLH in adults, and emphasizes the urgency of timely diagnosis and intervention.

Case report: EBV-related eye orbits and sinuses lymphohistiocytic infiltration responsive to rituximab in a patient with X lymphoproliferative syndrome type 1

Background and aims

X lymphoproliferative syndrome type 1 (XLP1) is a rare inborn error of immunity due to mutations of SH2D1A, encoding for slam-associated protein (SAP). The clinical phenotype includes severe mononucleosis, hemophagocytic lymphohistiocytosis (HLH), and B-cell lymphomas.

Methods

We report the case of a child affected with XLP1 who presented with an incomplete HLH, triggered by Epstein-Barr virus (EBV) and treated with rituximab, involving orbits and paranasal sinuses.

Results

The lesion was indistinguishable from lymphoma, complicating diagnosis and treatment. In addition, considering the high incidence of lymphoma in patients with XLP1, histology helped define its nature, driving therapeutic choices.

Conclusion

We described an unusual presentation of incomplete HLH in a patient affected with XLP1: an EBV-driven infiltration of the orbits and paranasal sinuses. This led us to a challenging differential diagnosis of lymphoma-associated hemophagocytic syndrome, which can be frequently observed in patients with XLP1. Considering the extremely poor prognosis of this clinical finding, we sought for a prompt diagnosis and managed to obtain it and to immediately establish the right treatment on the basis of the pathological finding.

Hemophagocytic lymphohistiocytosis during treatment of intracranial multifocal germinoma: a case report and literature review

Hemophagocytic lymphohistiocytosis (HLH), also known as hemophagocytic syndrome (HPS), is a benign histiocytosis with hyperreactive proliferation of the mononuclear phagocyte system caused by immune function abnormalities, which often occurs under the background of genetic mutations, inflammation, infection or tumors. Because the research on malignancy-associated HLH (M-HLH) is focused on hematological malignancies, reports on HLH secondary to solid tumors are rare. In this case, we report a 14-year-old girl who developed HLH during treatment for intracranial multifocal germinoma, and the disease was controlled after hormone combined with etoposide(VP-16) and other related treatments. To our knowledge, there have been no documented cases of HLH caused by intracranial multifocal germinoma.

Silvery Gray Hair Syndrome With Hemophagocytic Lymphohistiocytosis: A Case Report

Griscelli syndrome (GS) is a rare autosomal recessive disorder, which has been classified into three subtypes based on clinical and genetic differences. GS subtype 2 is commonly associated with hemophagocytic lymphohistiocytosis (HLH) and recurrent infections due to immunodeficiency. In this study, we describe a four-month-old boy with genetically proven GS2, with neurological and immunological manifestations. He presented with fever, refusal of feeds, drowsiness, and multiple episodes of seizures. Examination revealed hypopigmented skin, silvery gray hair, and organomegaly. The child developed features of HLH, fulfilling clinical and laboratory criteria. Neuroimaging findings were in concordance with HLH of the central nervous system. Microscopic examination of the hair showed clumps of melanin pigment along the hair shaft. All findings were in favor of GS type 2, complicated with HLH, which was later confirmed with a homozygous deletion of the RAB27A gene on exome sequencing. Unfortunately, the baby succumbed to death due to severe sepsis and multiorgan dysfunction. The silvery gray hair, with typical hair microscopic findings, and association with HLH are strong indicators for this potentially fatal condition and aid in prompt diagnosis and initiation of treatment. Hematopoietic stem cell transplantation is the only lifesaving treatment option.

Prognostic factors in patients with secondary hemophagocytic lymphohistioc ytosis in a Chinese cohort

Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory syndrome with high mortality mediated by an unbridled and persistent activation of cytotoxic T lymphocytes and natural killer cells. However, the influence factors of early death in adult sHLH patients are still not fully elucidated, which need further investigating. We have conducted an observational study of adult HLH patients between January 2016 and December 2022. All patients are enrolled according to HLH-2004 criteria. Clinical manifestations, laboratory data, treatments, and outcomes have been recorded. Influence factors associated with prognosis are calculated by using logistic regression models. Overall, 220 patients enrolled in this study. The etiologies of HLH were divided into five groups including autoimmune-associated hemophagocytic syndrome (AAHS) (n = 90, 40.9%), malignancies (n = 73, 33.2%), EBV-HLH (n = 18, 8.2%), infection excluded EBV (n = 24, 10.9%), and other triggers (n = 15, 6.8%). Among them, EBV-HLH had the highest mortality (77.8%), and AAHS had the lowest mortality (14.4%). Multivariate analysis indicated that age (≥ 38 years old), cytopenia ≥ 2 lines, platelets (≤ 50 × 109/L), aspartate aminotransferase (≥ 135U/L), prothrombin time (≥ 14.9 s) and activated partial thromboplastin time (≥ 38.5s), EBV, and fungal infection are independent risk factors for poor prognosis of HLH. Adult HLH patients with elder age, cytopenia ≥ 2 lines, levels of decreased platelets, increased AST, prolonged PT and APTT, EBV, and fungal infection tend to have a poor prognosis.

HLH as an additional warning sign of inborn errors of immunity beyond familial-HLH in children: a systematic review

Background

Hemophagocytic Lymphohistiocytosis (HLH) is a rare and life-threatening condition characterized by a severe impairment of the immune homeostasis. While Familial-HLH (FHL) is a known cause, the involvement of other Inborn Errors of Immunity (IEI) in pediatric-HLH remains understudied.

Objective

This systematic review aimed to assess the clinical features, triggers, laboratory data, treatment, and outcomes of pediatric HLH patients with IEI other than FHL (IEInotFHL), emphasizing the importance of accurate identification and management.

Methods

A systematic search for studies meeting inclusion criteria was conducted in PubMed, EMBASE, MEDLINE, and Cochrane Central. Quality assessment was performed through JBI criteria.

Results

A comprehensive search yielded 108 records meeting inclusion criteria, involving 178 patients. We identified 46 different IEI according to IUIS 2022 Classification. Combined immunodeficiencies, immune dysregulation disorders, and phagocyte defects were the IEI most frequently associated with HLH. In 75% of cases, HLH preceded the IEI diagnosis, often with an unrecognized history of severe infections. Triggers reflected the specific infection susceptibilities within IEI groups. Liver and central nervous system involvement were less common than in FHL cases. Treatment approaches and outcomes varied, with limited long-term follow-up data, limiting the assessment of therapeutic efficacy across IEI groups.

Conclusion

A comprehensive evaluation encompassing immunological, infectious, and genetic aspects is essential in pediatric-HLH. Relying solely on FHL or EBV susceptibility disorders tests is insufficient, as diverse other IEI can contribute to HLH. Early recognition of HLH as a potential warning sign can guide timely diagnostic investigations and facilitate tailored therapeutic interventions for improved outcomes.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=371425, PROSPERO, CRD42022371425.

Ruxolitinib-based regimen in children with primary hemophagocytic lymphohistiocytosis

Primary hemophagocytic lymphohistiocytosis (pHLH) is a rare immune disorder and hematopoietic stem cell transplan- tation (HSCT) is the only potentially curative treatment. Given the high pre-HSCT mortality of pHLH patients reported in the HLH-2004 study (17%), more regimens to effectively control the disease and form a bridge with HSCT are needed. We conducted a retrospective study of pHLH children treated by ruxolitinib (RUX)-based regimen. Generally, patients received RUX until HSCT or unacceptable toxic side-effect. Methylprednisolone and etoposide were added sequentially when the disease was suboptimally controlled. The primary end point was 1-year overall survival. Twenty-one pHLH patients (12 previously treated and 9 previously untreated) were included with a median follow-up of 1.4 years. At last follow-up, 17 (81.0%) patients were alive with a 1-year overall survival of 90.5% (95% confidence interval: 84.1-96.9). Within the first 8 weeks, all patients had an objective response, of which 19 (90.5%) achieved complete response (CR) and two (9.5%) achieved partial response (PR) as a best response. Seventeen (81.0%) patients received HSCT, of which 13 (76.5%) had CR, three (17.6%) had PR and one (5.9%) had disease reactivation at the time of HSCT. Fifteen (88.2) patients were alive post- HSCT. Notably, eight (38.1%) patients received zero doses of etoposide, suggesting the potential of RUX-based regimen to reduce chemotherapy intensity. Patients tolerated RUX-based regimen well and the most frequently observed adverse events were hematologic adverse events. Overall, RUX-based regimen was effective and safe and could be used as a bridge to HSCT for pHLH children.

Brain MRI imaging markers associated with death in children with central nervous system involvement of hemophagocytic lymphohistiocytosis

OBJECTIVES

To investigate the association of brain MRI and clinical variables with death in children with central nervous system involvement of hemophagocytic lymphohistiocytosis (CNS-HLH).

METHODS

Clinical and brain MRI data of children with CNS-HLH from January 2012 to March 2022 were reviewed retrospectively. Patients were divided into the deceased group and the surviving group. The intergroup differences of seven brain MRI variables, twelve clinical variables, and underlying diseases were studied.

RESULTS

One hundred and fourteen patients were included in this study, consisting of 59 who died and 55 who survived. The included clinical variables did not show statistically independent correlation with patients' deaths. For MRI variables, a multivariate analysis demonstrated restricted diffusion of lesion (OR = 9.64, 95% CI: 3.39-27.43, p < 0.001) and count of affected brain regions (CABR) (OR = 1.24, 95% CI: 1.03-1.49, p = 0.02) were independent risk factors for death. ROC curve showed CABR (AUC = 0.79, 95% CI: 0.70-0.87, p < 0.001) is highly predictive for mortality with an optimal cutoff value of 4.5 (sensitivity 76%, specificity 73%). For HLH subtypes, familial HLH (F-HLH, OR = 9.90, 95% CI: 2.01-48.87, p = 0.005) and immune-compromise-related HLH (IC-HLH, OR = 4.95, 95% CI: 1.40-17.46, p = 0.01) presented statistically stronger association with death than infection-related HLH. F-HLH and IC-HLH preferred to have large lesions, restricted diffusion, and more brain regions involved than other subtypes.

CONCLUSION

Brain MRI features exhibit independent prediction for mortality in children with CNS-HLH, and HLH subtypes pose effects on patient outcomes and brain MRI findings.

CLINICAL RELEVANCE STATEMENT

The number of affected brain regions and diffusion restriction of lesion exhibit significant correlation with mortality in children diagnosed with CNS-hemophagocytic lymphohistiocytosis, and may serve as candidate MRI markers for the prediction of the disorder's severity.

KEY POINTS

• The brain MRI markers, restricted diffusion of lesion and count of affected brain regions, significantly correlated with death. • Familial and immune-compromise-related hemophagocytic lymphohistiocytosis presented statistically stronger association with death than infection-related subtype. • Brain MRI is potential in death-predicting for children with central nervous system involvement of hemophagocytic lymphohistiocytosis.

Salvage Therapy and Allogeneic Hematopoietic Cell Transplantation for the Severe Cytokine Storm Syndrome of Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) can be considered as a severe cytokine storm syndrome disorder. HLH typically manifests as a life-threatening inflammatory syndrome characterized by fevers, cytopenias, hepatosplenomegaly, and various other accompanying manifestations such as coagulopathy, hepatitis or liver failure, seizures or altered mental status, and even multi-organ failure. Standard up-front treatments do not always bring HLH into remission or maintain adequate response, and salvage or alternative therapies are often needed. For patients with genetic diseases that cause HLH, curative allogeneic hematopoietic cell transplantation is usually offered to prevent future episodes of life-threatening HLH. Here, we will discuss the options and approaches for salvage therapy and hematopoietic cell transplantation for patients with HLH.

Diagnosis and investigation of suspected haemophagocytic lymphohistiocytosis in adults: 2023 Hyperinflammation and HLH Across Speciality Collaboration (HiHASC) consensus guideline

Haemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterised by persistently activated cytotoxic lymphocytes and macrophages, which, if untreated, leads to multiorgan dysfunction and death. HLH should be considered in any acutely unwell patient not responding to treatment as expected, with prompt assessment to look for what we term the three Fs-fever, falling blood counts, and raised ferritin. Worldwide, awareness of HLH and access to expert management remain inequitable. Terminology is not standardised, classification criteria are validated in specific patient groups only, and some guidelines rely on specialised and somewhat inaccessible tests. The consensus guideline described in this Health Policy was produced by a self-nominated working group from the UK network Hyperinflammation and HLH Across Speciality Collaboration (HiHASC), a multidisciplinary group of clinicians experienced in managing people with HLH. Combining literature review and experience gained from looking after patients with HLH, it provides a practical, structured approach for all health-care teams managing adult (>16 years) patients with possible HLH. The focus is on early recognition and diagnosis of HLH and parallel identification of the underlying cause. To ensure wide applicability, the use of inexpensive, readily available tests is prioritised, but the role of specialist investigations and their interpretation is also addressed.

History of Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a severe cytokine storm syndrome (CSS), which until the turn of the century, was barely known but is now receiving increased attention. The history of HLH dates back to 1939 when it was first described in adults, to be followed in 1952 by the first description of its primary, familial form in children. Secondary forms of HLH are far more frequent and occur with infections, malignancies, metabolic diseases, iatrogenic immune suppression, and autoinflammatory/autoimmune diseases. Identification of the genetic defects leading to the defective function of natural killer (NK) cells and cytotoxic T cells as well as the corresponding mouse models have revolutionized our understanding of HLH and of immune function. Diagnosis relies on clinical and laboratory criteria; functional and genetic tests can help separate primary from secondary forms. Treatment with immunochemotherapy and hematopoietic stem cell transplantation has considerably improved survival in children with primary HLH, a formerly uniformly fatal disease.

Hemophagocytic lymphohistiocytosis in children with Griscelli syndrome type 2: genetics, laboratory findings and treatment

Griscelli syndrome is a rare inherited autosomal recessive syndrome that causes immunodeficiency. Hemophagocytic lymphohistiocytosis (HLH), which is characterized by a high mortality rate, may develop because of Griscelli syndrome type 2 (GS2). We aimed to share our experience with the diagnosis and treatment methods of patients who developed HLH secondary to GS2. Patients with GS2 who were diagnosed and treated for HLH between 2017 and 2022 at the Cukurova University Division of Pediatric Allergy & Immunology and Division of Pediatric Hematology were included in the study. Microscopic examination of the hair shaft and next-generation sequencing for molecular genetic testing of RAB27A helped in the diagnosis of GS2. The first clinical presentation of 8 patients was HLH. One patient presented with CNS involvement and two patients presented with recurrent fever. Over 5 years, GS2 was diagnosed in 15 patients, of whom 11 (73.3%) developed HLH. The HLH-2004 protocol was used to treat these patients. Hematopoietic stem cell transplantation (HSCT) was performed in five patients who were matched with suitable donors. While all patients who underwent HSCT were alive, three patients who could not undergo HSCT because no donor could be found died. Deletion of CAAGC at nucleotides 514_518 in GS2 patients is associated with CNS involvement and a poor prognosis. HLH may be the first sign of presentation in patients with GS2. Although further research is needed, regardless of the conditioning regimen utilized, early HSCT remains the primary therapy option for preventing GS2-induced mortality in HLH.

Neuroimaging manifestations of paediatric histiocytoses

Histiocytoses are rare multi-system disorders marked by abnormal histiocyte cell proliferation, affecting children with diverse clinical presentations. Classified into five groups in 2016, including Langerhans-related (L), cutaneous (C), malignant (M), Rosai-Dorfman disease (R) and haemophagocytic lymphohistiocytosis (H), newer entities such as ALK-positive histiocytosis have also emerged, heralding the era of molecular (sub)classification. Common entities include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), Rosai-Dorfman disease (RDD) and haemophagocytic lymphohistiocytosis (HLH). This pictorial essay aids radiologists in recognising and differentiating paediatric histiocytoses based on unique neuroimaging features.

Unmasking of systemic lupus erythematosus in a patient with hemophagocytic lymphohistiocytosis- macrophage activation syndrome (HLA-MAS) and diffuse alveolar hemorrhage

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome caused by macrophages and cytotoxic T cells with aberrant activation. The primary (genetic) form, which is caused by mutations that affect lymphocyte cytotoxicity and immune regulation, is most prevalent in children, whereas the secondary (acquired) form is prevalent in adults. Secondary HLH is commonly caused by infections or cancers, but it can also be caused by autoimmune disorders, in which case it is known as macrophage activation syndrome (MAS; or MAS-HLH). A 25-year-old female presented with a high-grade fever that lasted for two weeks. His laboratory results revealed pancytopenia, neutropenia, hypertriglyceridemia, hypofibrinogenemia, and hyperferritinemia. Based on the clinical presentation and laboratory findings, a provisional diagnosis of HLH has been made. A HLH protocol was utilized to treat the patient. During the course of hospitalization, systemic lupus erythematosus (SLE) was identified as the underlying cause. She improved dramatically after receiving an immunosuppressive regimen of etoposide, cyclosporine, and dexamethasone according to HLH protocol-2004 with individualized modifications. The clinician should be aware that HLH may be the initial manifestation of underlying SLE. Early diagnosis and aggressive, individualized treatment are the key to improving outcomes.

Hemophagocytic Lymphohistiocytosis Caused by a Severe Epstein-Barr Virus Infection in a Young Patient Presenting With Hiccups

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome characterized by a pathologic immune response in the setting of infection, malignancy, acute illness, or any immunological stimulus. Infection is the most common etiology of HLH. HLH involves aberrant activation of lymphocytes and macrophages with resultant hypercytokinemia due to an inappropriately stimulated and ineffective immune response. Here, we present the case of a previously healthy 19-year-old male presenting with hiccups and scleral icterus, who was found to have HLH due to a severe Epstein-Barr virus infection. Despite a morphologically normal bone marrow biopsy, the patient met the diagnostic criteria for HLH, including a low natural killer cell count and elevated soluble interleukin-2 receptor. Notably, ferritin was severely elevated at 85,810 ng/mL. The patient was treated with an induction course of dexamethasone intravenously for eight weeks. Since HLH can progress into multi-organ failure, timely diagnosis and prompt initiation of treatment are critical. Novel disease-modifying therapies and further clinical trials are warranted to treat this potentially fatal immunological disease with multisystem ramifications.

Epstein-Barr Virus-Related Hemophagocytic Lymphohistiocytosis with Central Nervous System Symptoms

Hemophagocytic lymphohistiocytosis (HLH) involves pathological histiocytes and phagocytosis of normal blood cells through activation of inflammatory cytokines. We report a case of Epstein-Barr virus-HLH in a 75-year-old woman who presented with fever, thrombocytopenia, and loss of consciousness. Epstein-Barr virus-HLH was diagnosed after we identified massive hemophagocytosis in bone marrow and Epstein-Barr virus DNA in cerebrospinal fluid. The HLH-2004 protocol was applied, and lactate dehydrogenase levels-which reflect HLH disease status-decreased. However, persistent loss of consciousness and multiple organ failure led to the patient's death on day 18. Most cases of primary and secondary HLH involve pediatric patients; adult cases are rare. Few cases of central nervous system involvement in older adults have been reported. Therefore, accumulation of more data will help in developing better treatment strategies.

A Case Report on CNS Hemophagocytic Lymphohistiocytosis in an Infant With Dengue Hemorrhagic Fever

India is an endemic country for dengue. The incidence of hemophagocytic lymphohistiocytosis (HLH) with dengue in children has been well-reported. However, central nervous system (CNS) HLH associated with dengue has not been described in the literature yet. We hereby report a novel case of CNS HLH triggered by dengue infection. An eight-month-old, well-grown male infant with uneventful antenatal, perinatal, and neonatal history was admitted with a history of febrile illness associated with cough, cold, vomiting, and loose motions and one episode of hematochezia and hepatosplenomegaly on examination. Investigations revealed bi-cytopenia, hyper-ferritinemia, deranged coagulation profile, liver function test, and hypo-fibrinogenemia. Dengue non-structural protein 1 ( NS1) antigen was positive. The child was given dexamethasone and continued supportive care with a diagnosis of dengue shock syndrome. The child showed an overall transient improvement, however, he had rebound fever followed by right focal convulsion on Day 9 of steroids. MRI brain revealed areas of diffusion-restricted embolic infarcts with diffuse leptomeningeal enhancement and mild cerebral edema, and CSF showed a total leukocyte count of 80 cells with 75% lymphocytic picture, histiocytes with hemophagocytosis, confirmatory of CNS HLH. Intrathecal methotrexate, hydrocortisone, and intravenous (IV) etoposide were started. However, the child succumbed to his illness. CNS involvement in dengue-triggered HLH needs to be suspected despite subtle neurological signs and aggressively managed following a multi-departmental approach to ensure the best clinical and neuro-developmental outcomes.

Chronic Active Epstein-Barr Virus Infection With Central Nervous System Involvement in Children: A Clinical Study of 22 Cases

OBJECTIVE

To analyze the clinical features, treatment, and prognosis of chronic active Epstein-Barr virus infection (CAEBV) with central nervous system (CNS) involvement in children.

METHODS

Patients with CAEBV admitted to Beijing Children's Hospital, Capital Medical University, were enrolled in this study from January 2017 to December 2020. They were divided into a CNS group and a non-CNS group based on the presence of CNS involvement.

RESULTS

Twenty-two patients developed CNS disease, accounting for 23.9% (22/92) of CAEBV patients in the same period. Of these, only 2 of 22 patients presented initially with neurologic symptoms in the CNS group, and they all improved after treatment. Cerebrospinal fluid (CSF) examination demonstrated normal protein concentration and cell number in all patients with CNS involvement. Only 7 patients were positive for CSF EBV-DNA. Twenty-one patients had neuroimaging abnormalities, such as white matter signal abnormalities, encephalography or calcification. In the CNS group, 7 (31.8%) patients died, including 5 who died of active hemophagocytic lymphohistiocytosis, 1 died of unrelated causes, and 1 died of respiratory failure caused by pulmonary lymphoproliferative disease progression after transplantation. The 3-year overall survival was lower in the CNS group than in the non-CNS group (63.6% ± 11.9% versus 86.9% ± 4.1%, P = 0.027). Hemophagocytic lymphohistiocytosis (HLH) is an independent risk factor for CNS involvement in patients with CAEBV (OR = 2.946, 95% CI: 1.042-8.335, P = 0.042). Compared with the non-CNS group, blood EBV-DNA loads and CD4+/CD8+ ratio of T lymphocytes in the CNS group were higher (P < 0.001), while fibrinogen levels and natural killer (NK)-cell activity were lower (P = 0.047). Children with CAEBV were more likely to develop CNS diseases with low NK-cell activity (NK-cell activity < 14.00%, P = 0.023) or high alanine aminotransferase (ALT) levels (ALT levels > 40 U/L, P = 0.032).

CONCLUSION

CAEBV with CNS involvement has nonspecific clinical manifestations, laboratory data, neuroimaging but has a worse prognosis. Blood fibrinogen levels and NK-cell activity in CAEBV children with CNS involvement are lower than in those without CNS involvement. In contrast, blood EBV-DNA loads and CD4+/CD8+ ratio of T lymphocytes are higher. Children with CAEBV who presented with HLH, NK-cell activity <14.00%, serum ALT >40 U/L and high-blood EBV-DNA loads are prone to develop CNS diseases.

Paediatric haemophagocytic lymphohistiocytosis: clinical presentation and outcome of 20 patients at a single institution

Paediatric haemophagocytic lymphohistiocytosis (pHLH) is a potentially life-threatening condition with significant diagnostic and therapeutic difficulties. The purpose of this study was to describe the clinical presentation, the diagnostic challenges, and the outcomes of haemophagocytic lymphohistiocytosis (HLH) in children assessed at Mukalla Hospital, Yemen. Data from 20 medical records of HLH patients admitted between January 2010 and May 2022 were retrospectively analysed. The median age at presentation was 3.5 ± 5.1 years. Male: female ratio was 1:1. The median time for referral to the hospital was 30 ± 64 days. The most common clinical manifestations were fever and pallor in 95% of cases, and splenomegaly (85%). Hepatomegaly, chest, renal and neurological manifestations were detected in 80%, 45%, 15% and 20% of cases, respectively. Bone marrow haemophagocytosis was detected in 60% of cases. Sixteen patients fulfilled the HLH diagnostic criteria, and 11 patients (55%) received the HLH 2004 protocol. Out of the 20 patients, three (15%) patients are alive. Fourteen patients died, with overall mortality of 82.35%. All mortalities were due to HLH disease with multi-organ failure. Relapse was noticed in five patients either during treatment or after full recovery. pHLH is a challenging emergency with a high mortality rate. High clinical suspicion is essential for early detection and intervention to improve the prognosis.

Second Allogeneic Hematopoietic Stem Cell Transplantation for Hemophagocytic Syndrome with Engraftment Failure

This study aims to assess the efficacy of second allogeneic hemopoietic stem cell transplantation (allo-HSCT) for treating hemophagocytic syndrome with first engraftment failure. Among a total of 35 patients who underwent allo-HSCT between June 2015 and July 2021 for HLH, 10 patients who underwent a second HSCT following graft rejection were retrospectively analyzed. Various factors, such as the treatment course and outcome, the remission status, donor selection, and the conditioning regimen of patients before second allo-HSCT, were scrutinized for transplant-related complications and transplant-related mortality, as well as transplant outcomes. All the subjects have achieved complete donor engraftment, in which the neutrophils and platelets engraftment occurred in a median time of 12 d (range 10–19 d) and 24 d (range 11–97 d), respectively. Among the selected subjects, 20% of patients are diseased due to transplant-related thrombotic microangiopathy. Further, 90% of patients are diagnosed with aGVHD, in which 3 of them with grade I aGVHD, one patient with grade II aGVHD, two patients with grade III GVHD, and three patients with localized chronic GVHD. Moreover, 70% of patients showed signs of combined viral infections. Despite the complex symptoms, the overall survival rate is around 80%, with transplant-related mortality and the incidence of post-transplant GVHD of 20% and 60%, respectively. Together, our findings indicated that the second allo-HSCT showed great potential in treating hemophagocytic syndrome with engraftment failure.

Hemophagocytic Lymphohistiocytosis After Greenlight Laser Prostate Surgery

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic inflammatory disease. Multiple risk factors have been defined for the manifestation of HLH. While infection remains the top risk factor, having multiple surgical procedures has also been suggested as a potential risk factor for HLH. Our patient presented with generalized weakness, weight loss, and fatigue after having a greenlight laser prostatectomy for benign prostate hypertrophy; the patient deteriorated rapidly and was found to fulfill the HLH 2004 and modified criteria. We believe this patient had a rare bone marrow disorder with a rare complicated clinical and laboratory presentation.

Misdiagnosis of adult primary hemophagocytic lymphohistiocytosis as NK/T-cell lymphoma: A case report

We reported a case of a 19-year-old male patient with central nervous system symptoms as the main clinical manifestations, and multiple intracranial and abdominal occupying lesions visualized by imaging examinations, who was initially misdiagnosed as NK/T-cell lymphoma but poorly responsive to the treatment. Finally, he was diagnosed as familial hemophagocytic lymphohistiocytosis type-2 by genome sequencing, perforin test and pedigree study. The patient survived well after allogeneic hematopoietic stem cell transplantation. Central nervous system symptoms could be the main clinical manifestations in patients with primary hemophagocytic lymphohistiocytosis , whose early-stage manifestations of blood system were usually atypical, easily leading to misdiagnosis. In clinical practice, primary hemophagocytic lymphohistiocytosis should be considered in patients with central nervous system symptoms and unknown causes. The combination of rapid immunological function test and genome sequencing contributes to the diagnosis of primary hemophagocytic lymphohistiocytosis.

The pathogenesis, diagnosis, prevention, and treatment of CAR-T cell therapy-related adverse reactions

Chimeric antigen receptor (CAR)-T cell therapy is effective in the treatment of refractory/relapsed (r/r) hematological malignancies (r/r B-cell lymphoblastic leukemia, B-cell lymphoma, and multiple myeloma). In addition, it is being explored as a treatment option for solid tumors. As of 31 March 2022, seven CAR-T therapies for hematological malignancies have been approved worldwide. Although CAR-T therapy is an effective treatment for many malignancies, it also causes adverse effects. The incidence of cytokine release syndrome (CRS), the most common adverse reaction after infusion of CAR-T cells, is as high as 93%.CRS, is the leading risk factor of immune effector cell-associated neurotoxicity syndrome (ICANS), as well as cardiovascular, hematological, hepatorenal, skin, pulmonary, and gastrointestinal toxicity. Severe adverse reactions complicated by CRS severely impede the widespread application of CAR-T therapy. The CAR-T product was initially approved in 2017; however, only limited studies have investigated the adverse reactions owing to CAR-T therapy compared to that of clinically approved drugs. Thus, we aimed to elucidate the mechanisms, risk factors, diagnostic criteria, and treatment of toxicities concurrent with CRS, thereby providing a valuable reference for the safe, effective, and widespread application of CAR-T therapy.

Clinical significance of cerebrospinal fluid soluble CD25 in pediatric hemophagocytic lymphohistiocytosis with central nervous system involvement

OBJECTIVE

To analyze the clinical significance of soluble CD25 (sCD25) levels in cerebrospinal fluid (CSF) in pediatric hemophagocytic lymphohistiocytosis (HLH) with central nervous system (CNS) involvement.

METHODS

All patients diagnosed with HLH admitted to Beijing Children's Hospital, Capital Medical University between January 1, 2017 and October 31, 2021 who received a measurement of their HLH-related parameters and CSF sCD25 levels at admission were enrolled in this study.

RESULTS

CSF sCD25 levels in patients with primary HLH were higher than those in patients with Epstein-Barr virus infection-associated HLH, and the median level was 444 pg/ml. The difference in CSF sCD25 levels between the non-CNS group and the CNS group was statistically significant (591 [259-33,643] pg/ml vs. 123 (36-437) pg/ml, p < .001). The best cutoff value of CSF sCD25 was 273.5 pg/ml (AUC = 0.987, 95% CI: 0.972-1.000), with sensitivity, specificity, positive predictive values, and negative predictive values of 96.4%, 92.8%, 81.8%, and 98.7%, respectively. CSF sCD25 in the severe CNS involvement group was significantly higher than that in the nonsevere CNS involvement group (p = .014). The 3-year overall survival (OS) of patients with high CSF sCD25 levels was lower than that of patients with low CSF sCD25 levels(71.6% ± 8.1% vs. 93.3% ± 2.9%, hazard ratio [HR] = 3.637, p = .003).

CONCLUSION

Increased CSF sCD25 levels in active disease can predict CNS-HLH. Primary HLH has a higher CSF sCD25 level than Epstein-Barr virus infection-associated HLH. Patients who are diagnosed with CNS-HLH with CSF sCD25 levels higher than 273.5 pg/ml are more likely to develop severe CNS involvement, suggesting a poor prognosis.

Cytokine storm and targeted therapy in hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyperinflammatory syndrome. The central pathogenesis is an explosive cytokine storm characterized by a significant increase in proinflammatory cytokines, including IL-1β, IL-6, IL-18, IFN-γ, and TNF-α. Meanwhile, negative regulatory factors, such as IL-10 and TGF-β, are also related to the production of HLH. Exploring the specific mechanism of cytokine storms could provide ideas regarding targeted therapy, which could be helpful for early treatment to reduce the mortality of HLH. Although some research has focused on the advantages of targeted therapies, there is still a lack of a comprehensive discourse. This article attempts to summarize the mechanisms of action of various cytokines and provide a therapeutic overview of the current targeted therapies for HLH.

Treatment Strategies for Central Nervous System Effects in Primary and Secondary Haemophagocytic Lymphohistiocytosis in Children

Purpose of Review

This review presents an appraisal of current therapeutic options for the treatment of central nervous system haemophagocytic lymphohistiocytosis (CNS-HLH) in the context of systemic disease, as well as when CNS features occur in isolation. We present the reader with a diagnostic approach to CNS-HLH and commonly used treatment protocols. We discuss and evaluate newer treatments on the horizon.

Recent Findings

Mortality is high in patients who do not undergo HSCT, and while larger studies are required to establish benefit in many treatments, a number of new treatments are currently being evaluated. Alemtuzumab is being used as a first-line treatment for CNS-HLH in a phase I/II multicentre prospective clinical trial as an alternative to traditional HLH-1994 and 2004 protocols. It has also been used successfully as a second-line agent for the treatment of isolated CNS-HLH that is refractory to standard treatment. Ruxolitinib and emapalumab are new immunotherapies that block the Janus kinase—Signal Transducer and Activator of Transcription (JAK-STAT) pathway that have shown efficacy in refractory HLH, including for CNS-HLH disease.

Summary

Treatment of CNS-HLH often requires HLH-94 or 2004 protocols followed by haematopoietic stem cell transplantation (HSCT) to maintain remission, although relapse can occur, particularly with reduced intensity conditioning if donor chimerism falls. CNS features have been shown to improve or stabilise following HSCT in CNS-HLH in the context of systemic disease and in isolated CNS-HLH. Encouraging reports of early cohort studies suggest alemtuzumab and the Janus kinase (JAK) inhibitor ruxolitinib offer potential salvage therapy for relapsed and refractory CNS-HLH. Newer immunotherapies such as tocilizumab and natalizumab have been shown to be beneficial in sporadic cases. CNS-HLH due to primary gene defects may be amenable to gene therapy in the future.

Neuroinflammation Associated With Inborn Errors of Immunity

The advent of high-throughput sequencing has facilitated genotype-phenotype correlations in congenital diseases. This has provided molecular diagnosis and benefited patient management but has also revealed substantial phenotypic heterogeneity. Although distinct neuroinflammatory diseases are scarce among the several thousands of established congenital diseases, elements of neuroinflammation are increasingly recognized in a substantial proportion of inborn errors of immunity, where it may even dominate the clinical picture at initial presentation. Although each disease entity is rare, they collectively can constitute a significant proportion of neuropediatric patients in tertiary care and may occasionally also explain adult neurology patients. We focus this review on the signs and symptoms of neuroinflammation that have been reported in association with established pathogenic variants in immune genes and suggest the following subdivision based on proposed underlying mechanisms: autoinflammatory disorders, tolerance defects, and immunodeficiency disorders. The large group of autoinflammatory disorders is further subdivided into IL-1β-mediated disorders, NF-κB dysregulation, type I interferonopathies, and hemophagocytic syndromes. We delineate emerging pathogenic themes underlying neuroinflammation in monogenic diseases and describe the breadth of the clinical spectrum to support decisions to screen for a genetic diagnosis and encourage further research on a neglected phenomenon.

Aggressive Natural Killer Cell Leukemia in an Adolescent Patient: A Case Report and Literature Review

Aggressive natural killer cell leukemia (ANKL) is a rare malignant tumor, especially uncommon in children. ANKL has very aggressive clinical course and bad prognosis and is usually caused by Epstein-Barr virus infection. ANKL often has clinical manifestations of hemophagocytic lymphohistiocytosis (HLH) and can be easily treated as HLH, which might complicate this aggressive disease. Here we report an ANKL in adolescent whose clinical presentation was highly aggressive and response to L-asparaginase containing chemotherapy was very bad. Early-onset Flow cytometry of peripheral blood and bone marrow help make the diagnosis.

Treosulfan-Based Conditioning in Matched Family, Unrelated and Haploidentical Hematopoietic Stem Cell Transplantation for Genetic Hemophagocytic Lymphohistiocytosis: Experience and Outcomes over 10 Years from India

We aimed to analyze data in children with primary hemophagocytic lymphohistiocytosis (HLH) who underwent hematopoietic stem cell transplantation (HSCT). We performed a retrospective study where children up to 18 years, with primary HLH and who underwent HSCT from January 2011 to December 2019, were included. Twenty-five children with genetic HLH underwent HSCT, including variants (Griscelli syndrome (GS2) 7, Chediak-Higashi syndrome (CHS) 2, XIAP mutation 2). Donors were matched family 8 (32%), umbilical cord blood unit 3 (12%), matched unrelated 2 (8%), haploidentical HSCT 12 (48%), (TCR alpha/beta depletion 2 and post-transplant cyclophosphamide 10). With treosulfan-based conditioning, engraftment was achieved in 23/25 (92%) transplants (100% in haplo-HSCT), with sustained complete chimerism in 87%. Disease-free survival was noted in 2/3 children with stable mixed chimerism. Graft-versus-host disease (GVHD) of grade I/II was noted in 6 (24%), grade III in 3 (13%); chronic limited skin GVHD in 2 (12%) children. Overall survival was 72% (87.5% in matched donor, 66.7% in the haplo-HSCT), 71% in GS2, 50% in CHS, 100% in XIAP. HSCT is curative in primary HLH with acceptable disease-free survival with mixed chimerism. Haplo-HSCT is a viable option for those without matched family or unrelated donors.

Comparison of the clinical features and outcome of children with hemophagocytic lymphohistiocytosis (HLH) secondary to visceral leishmaniasis and primary HLH: a single-center study

Background

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive inflammation. We aimed to describe the clinical and laboratory findings of HLH patients secondary to Visceral leishmaniasis (VL) and their treatment outcome during a 4-year follow-up period compared to primary HLH.

Method

Forty children with primary HLH confirmed by genetic study and 20 children with HLH secondary to VL confirmed by a blood or bone marrow polymerase chain reaction from 2014 to 2018 in Shiraz, Fars province, Southern Iran, were enrolled.

Results

The median age at diagnosis was 11.5 months (range 1–170), and 56.7% were male. Fever and splenomegaly were the most frequent clinical presentations. 93.3% of the subjects had an HScore > 169, which had a good correlation with HLH-2004 criteria (r = 0.371,P = 0.004). Patients with primary HLH experienced more thrombocytopenia (P = 0.012) and higher alanine transaminase (P = 0.016), while patients with VL-associated HLH had higher ferritin (P = 0.034) and erythrocyte sedimentation rate (P = 0.011). Central nervous system (CNS) involvement occurred in 38.3% of patients. The mortality rate was higher in patients with CNS disease (61% vs. 35%,P = 0.051). The 3-yr overall survival rate was 35.9%. (24% in primary HLH and 100% in VL-associated HLH,P < 0.001). In Cox regression analysis, platelet count < 100,000/μl (hazard ratio 4.472, 95% confidence interval 1.324–15.107,P = 0.016) correlated with increased mortality in patients with primary HLH.

Conclusion

VL is a potential source of secondary HLH in regions with high endemicity. Treatment of the underlying disease in VL-associated HLH is sufficient in most cases, with no need to start etoposide-based chemotherapy.

Histiocytic disorders

The historic term 'histiocytosis' meaning 'tissue cell' is used as a unifying concept for diseases characterized by pathogenic myeloid cells that share histological features with macrophages or dendritic cells. These cells may arise from the embryonic yolk sac, fetal liver or postnatal bone marrow. Prior classification schemes align disease designation with terminal phenotype: for example, Langerhans cell histiocytosis (LCH) shares CD207+ antigen with physiological epidermal Langerhans cells. LCH, Erdheim-Chester disease (ECD), juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are all characterized by pathological ERK activation driven by activating somatic mutations in MAPK pathway genes. The title of this Primer (Histiocytic disorders) was chosen to differentiate the above diseases from Langerhans cell sarcoma and malignant histiocytosis, which are hyperproliferative lesions typical of cancer. By comparison LCH, ECD, RDD and JXG share some features of malignant cells including activating MAPK pathway mutations, but are not hyperproliferative. 'Inflammatory myeloproliferative neoplasm' may be a more precise nomenclature. By contrast, haemophagocytic lymphohistiocytosis is associated with macrophage activation and extreme inflammation, and represents a syndrome of immune dysregulation. These diseases affect children and adults in varying proportions depending on which of the entities is involved.

Consensus-Based Guidelines for the Recognition, Diagnosis, and Management of Hemophagocytic Lymphohistiocytosis in Critically Ill Children and Adults

OBJECTIVE

Hemophagocytic lymphohistiocytosis is a hyperinflammatory syndrome that often requires critical care support and remains difficult to diagnose. These guidelines are meant to aid in the early recognition, diagnosis, supportive care, and treatment of patients with hemophagocytic lymphohistiocytosis in ICUs.

DATA SOURCES

The literature searches were performed with PubMed (MEDLINE).

STUDY SELECTION

Keywords and medical subject headings terms for literature search included "macrophage activation syndrome," hemophagocytic lymphohistiocytosis," and "hemophagocytic syndrome."

DATA EXTRACTION

The Histiocyte Society developed these consensus recommendations on the basis of published reports and expert opinions with level of evidence provided for each recommendation. They were endorsed by the Society of Critical Care Medicine.

DATA SYNTHESIS

Testing for hemophagocytic lymphohistiocytosis should be initiated promptly in all patients admitted to ICUs with an unexplained or disproportionate inflammatory response, especially those with rapid clinical deterioration. Meeting five or more of eight hemophagocytic lymphohistiocytosis 2004 diagnostic criteria serves as a valuable diagnostic tool for hemophagocytic lymphohistiocytosis. Early aggressive critical care interventions are often required to manage the multisystem organ failure associated with hemophagocytic lymphohistiocytosis. Thorough investigation of the underlying triggers of hemophagocytic lymphohistiocytosis, including infections, malignancies, and autoimmune/autoinflammatory diseases, is essential. Early steroid treatment is indicated for patients with familial hemophagocytic lymphohistiocytosis and is often valuable in patients with acquired hemophagocytic lymphohistiocytosis (i.e., secondary hemophagocytic lymphohistiocytosis) without previous therapy, including macrophage activation syndrome (hemophagocytic lymphohistiocytosis secondary to autoimmune/autoinflammatory disease) without persistent or relapsing disease. Steroid treatment should not be delayed, particularly if organ dysfunction is present. In patients with macrophage activation syndrome, whose disease does not sufficiently respond, interleukin-1 inhibition and/or cyclosporine A is recommended. In familial hemophagocytic lymphohistiocytosis and severe, persistent, or relapsing secondary macrophage activation syndrome, the addition of prompt individualized, age-adjusted etoposide treatment is recommended.

CONCLUSIONS

Further studies are needed to determine optimal treatment for patients with hemophagocytic lymphohistiocytosis in ICUs, including the use of novel and adjunct therapies.

Neurological involvement in secondary hemophagocytic lymphohistiocytosis in children

OBJECTIVES

To describe neurological characteristics and CNS involvement on MRI in secondary hemophagocytic lymphohistiocytosis (sHLH) and differentiate it from primary hemophagocytic lymphohistiocytosis (pHLH) and acute disseminated encephalomyelitis (ADEM).

METHODS

Nine children with sHLH who had neurological symptoms were retrospectively included. Characteristics of brain MRI were compared to those of 15 children with pHLH and neurological involvement and 44 children with ADEM.

RESULTS

Three children (33%) presented with isolated neurological symptoms. Neurological signs occurred within one month following Epstein-Barr virus primary infection or systemic juvenile arthritis exacerbation in 8 patients (89%). Eight children (89%) had MRI lesions. sHLH MRI lesions were distinct of those of pHLH by morphology and signal with more frequent hyposignal intensities on T1-weighted sequences (p = 0.01) and well-defined and less fuzzy lesions (p = 0.03). All patients survived and one patient presented severe motor and cognitive disability.

CONCLUSION

Neurological symptoms of sHLH are non-specific and their outcome is favorable in most of the children. MRI at onset may help to differentiate this condition from pHLH.

Continuous intravenous anakinra for treating severe secondary haemophagocytic lymphohistiocytosis/macrophage activation syndrome in critically ill children

The cytokine storm of secondary haemophagocytic lymphohistiocytosis (sHLH)/macrophage activation syndrome (MAS) can cause life-threatening multiorgan failure. Interleukin-1 (IL-1) receptor blockade with anakinra can be effective in the management of sHLH/MAS. Subcutaneous (SC) dosing regimens are widely described; however, intravenous (IV) dosing is advantageous where time-critical intervention is vital and where SC oedema and/or hypoperfusion limits absorption. We review three critically ill children (aged 9, 11 and 17) with sHLH and rapidly progressive multiorgan dysfunction, successfully treated with continuous IV anakinra infusion. This case series significantly enhances the incipient knowledge regarding the safety and efficacy of IV anakinra for life-threatening sHLH.

Cytomorphologic Features Found in Cerebrospinal Fluid Specimens of Hemophagocytic Lymphohistiocytosis Patients

OBJECTIVES

Central nervous system involvement is present in 70% of patients with hemophagocytic lymphohistiocytosis (CNS-HLH). CNS-HLH is defined by neurologic deficits, neuroimaging abnormalities, or positive cerebrospinal fluid (CSF) findings. The CSF cytomorphologic spectrum of CNS-HLH, however, has not been well investigated.

METHODS

A retrospective review was performed on 64 CSF specimens from pediatric and adult patients with HLH. Ten patients had clinicoradiologic evidence of CNS involvement.

RESULTS

We identified five CSF cytomorphologic patterns: (1) hemophagocytosis, (2) vacuolated macrophages without evidence of hemophagocytosis, (3) monocytes and/or nonvacuolated macrophages, (4) acellular specimens, and (5) bloody specimens. Patterns 1 and 2 were common in CNS-HLH and rare in patients without CNS involvement. The CSF cytomorphologic patterns did not correlate well with WBC counts or protein concentration.

CONCLUSIONS

Our study offers a comprehensive view of the cytomorphologic features seen in CSF specimens from patients with HLH.