Clinical presentation and outcome of pediatric patients with hemophagocytic lymphohistiocytosis in China: A retrospective multicenter study

Predicting relapsed/refractory disease in childhood hemophagocytic lymphohistiocytosis based on clinical features at diagnosis: A 13-year single-institute retrospective study in Thailand

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease. Relapsed/refractory disease is the main cause of death. This study aims to determine the prognostic indicators for relapsed/refractory disease in childhood HLH (R/R HLH). Infants and children under 18 years of age who were diagnosed with HLH according to HLH-2004 criteria, MAS-HLH criteria for rheumatologic diseases, or H-score undergoing treatment in Chiang Mai University hospital between 2010 and 2022 were included. Demographic data, clinical characteristics, and laboratory parameters were retrospectively reviewed. Out of 86 childhood HLH cases, 30 patients (34.9%) experienced R/R HLH. All patients with primary HLH developed R/R HLH. The most common form of secondary HLH was infection-associated hemophagocytic syndrome (IAHS), comprising 43 cases. Of these, 37.2% had relapsed or refractory disease. Univariable analysis identified several potential risk factors for R/R HLH, including younger age, severe disease status, higher HLH-2004 criteria scores, higher H-scores, overt DIC, higher pSOFA scores, and increased levels of aspartate aminotransferase, total bilirubin, and direct bilirubin. Multivariable logistic regression analysis revealed that a pSOFA score of ≥ 8 and age < 3 years were independent risk factors for R/R HLH, with adjusted odds ratios of 6.35 (95% confidence interval [CI], 1.18-34.19; P = 0.032) and 3.62 (95% CI, 1.04-12.63; P = 0.044), respectively. Children with HLH who have a pSOFA score of ≥ 8, or are younger than 3 years, are at a higher risk of relapsed or refractory disease. Further evaluation of management strategies in this context is warranted.

Hemophagocytic lymphohistiocytosis complicating septicemic melioidosis: A case report

Melioidosis is an infectious disease caused by Burkholderia pseudomallei. People infected with B. pseudomallei experience fever and skin changes, pneumonia, abscesses, and septic shock that could cause death. Hemophagocytic lymphohistiocytosis is a severe inflammatory syndrome due to the excess activation of macrophages and T cells. We report a 50-year-old hypertensive and diabetic male patient presented with high-grade intermittent fever with loss of appetite and weight loss for two months and a history of jaundice, backache and swelling of both feet for 15 days. Blood and bone marrow culture grew Burkholderia pseudomallei. A liver biopsy revealed Kupffer cell hyperplasia and hemophagocytosis. The patient was treated with an injection of dexamethasone 4mg intravenous three times a day for five days and tapered over 15 days with ceftazidime 2 gm intravenous three times a day for six weeks. Early suspicion in the diagnosis of hemophagocytic lymphohistiocytosis in septicemia can prevent severe complications, even death.

Familial Hemophagocytic Lymphohistiocytosis (FHLH) Perforin Deficiency: A Case Study and Literature Review

Hemophagocytic lymphohistocytosis (HLH) is a severe and fatal immunological disorder that is either primary (i.e., familial) or secondary (i.e., acquired). The primary type comprises autosomal recessive disorders with gene mutations related to natural killer cells and cytotoxic T-cells, whereas the secondary type is related to other pathological causes, such as Epstein-Barr virus, bacterial or fungal infection, autoimmune conditions or autoinflammatory diseases, metabolic disorders, and cancer. In this report, we discuss a 37-day-old male who was brought to the emergency room with fever, decreased activity, and hepatosplenomegaly, with a strong family history of unknown cause of death for three siblings who died at the ages of one to two months. A whole exome sequencing confirmed the clinical diagnosis of familial HLH due to mutation in the PRF1 gene. We note the special importance of genetic counselling and antenatal screening or early neonatal screening in families affected by HLH, as this case highlights the importance of early diagnosis and intervention of primary HLH.

Etoposide Therapy of Cytokine Storm Syndromes

Etoposide has revolutionized the treatment of primary as well as secondary hemophagocytic lymphohistiocytosis (HLH), and it is, together with corticosteroids, the most widely used therapy for HLH. In the early 1980s, long-term survival in primary HLH was <5% but with the etoposide-/dexamethasone-based protocols HLH-94 and HLH-2004, in combination with stem cell transplantation, 5-year survival increased dramatically to around 60% in primary HLH, and based on analyses from the HLH-2004 study, there is likely room for further improvement. Biologically, etoposide administration results in potent selective deletion of activated T cells as well as efficient suppression of inflammatory cytokine production. Moreover, etoposide has also been reported to promote programmed cell death (apoptosis) rather than proinflammatory lytic cell death (pyroptosis), conceivably ameliorating subsequent systemic inflammation, i.e., a treatment very suitable for cytokine storm syndromes (CSS). The combination of etoposide and corticosteroids may also be beneficial in cases of severe or refractory secondary HLH (sHLH) with imminent organ failure, such as infection-associated HLH caused by Epstein-Barr virus (EBV) or malignancy-triggered HLH. In CSS associated with rheumatic diseases (macrophage activation syndrome, MAS or MAS-HLH), etoposide is currently used as second- or third-line therapy. Recent studies suggest that etoposide perhaps should be part of an aggressive therapeutic intervention for patients with severe refractory or relapsing MAS, in particular if there is CNS involvement. Importantly, awareness of sHLH must be further increased since treatment of sHLH is often delayed, thereby missing the window of opportunity for a timely, effective, and potentially life-saving HLH-directed treatment.

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.

Comparative study of biomarkers for the early identification of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in infectious mononucleosis

BACKGROUND AND AIM

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) and infectious mononucleosis (EBV-IM) share mimic symptoms in the early stages of childhood development. We aimed to examine the clinical features and laboratory indices of these two diseases in children and uncover unique indicators to assist pediatricians in identifying these diseases early.

METHODS

We collected clinical data from 791 pediatric patients diagnosed with EBV-IM or EBV-HLH, compared the clinical traits and laboratory biomarkers presented in the two groups, and constructed predictive models based on them.

RESULTS

Patients with EBV-IM had greater ratios of cervical lymphadenopathy, eyelid edema, and tonsillitis, whereas individuals with EBV-HLH were more likely to have hepatomegaly and splenomegaly. When using the criteria of interleukin (IL)-10 > 89.6 pg/mL, interferon (IFN)-γ > 45.6 pg/mL, ferritin > 429 μg/L, D-dimer > 3.15 mg/L and triglycerides > 2.1 mmol/L, the sensitivity was 87.9%, 90.7%, 98.1%, 91.1% and 81.5% to predict EBV-HLH, while the specificity was 98.4%, 96.3%, 96.5%, 94.1% and 80.6%, respectively. A logistic regression model based on four parameters (IL-10, ferritin, D-dimer, and triglycerides) was established to distinguish EBV-HLH patients from EBV-IM patients, with a sensitivity of 98.0% and a specificity of 98.2%.

CONCLUSIONS

IL-10, IFN-γ, ferritin and D-dimer levels are significantly different between EBV-HLH and EBV-IM. Predictive models based on clinical signs and laboratory findings provide simple tools to distinguish the two situations.

Hypofibrinogenemia is an independent predictor of hemophagocytic lymphohistiocytosis in children with sepsis

Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening condition in children with sepsis. We herein aimed to identify clinical and laboratory predictors of HLH in children with sepsis. We conducted a retrospective study of 568 children with sepsis admitted to Guangdong Women and Children Hospital from January 2019 to June 2022. HLH, while rare (6.34%), proved to be a highly fatal complication (37.14%) in children with sepsis. Children with HLH had higher levels of aspartate aminotransferase, lactate dehydrogenase, triglycerides, and ferritin than children without HLH; conversely, they displayed decreased levels of neutrophils, hemoglobin, platelets, fibrinogen, and albumin. Additionally, the HLH group showed higher rates of prolonged fever (> 10 days), hepatomegaly, and splenomegaly than the non-HLH group. Our retrospective analysis identified hypofibrinogenemia (OR = 0.440, P = 0.024) as an independent predictor for the development of HLH in patients with sepsis. The optimal cutoff value for fibrinogen was found to be < 2.43 g/L. The area under the curve for diagnosing HLH was 0.80 (95% confidence interval: 0.73-0.87, P < 0.0001), with a sensitivity of 72.41% and specificity of 76.27%. Thus, hypofibrinogenemia emerges as a potentially valuable predictor for HLH in children with sepsis.

The 2022 EULAR/ACR Points to Consider at the Early Stages of Diagnosis and Management of Suspected Haemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome (HLH/MAS)

OBJECTIVE

Haemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening systemic hyperinflammatory syndromes that can develop in most inflammatory contexts. They can progress rapidly, and early identification and management are critical for preventing organ failure and mortality. This effort aimed to develop evidence-based and consensus-based points to consider to assist clinicians in optimising decision-making in the early stages of diagnosis, treatment and monitoring of HLH/MAS.

METHODS

A multinational, multidisciplinary task force of physician experts, including adult and paediatric rheumatologists, haematologist/oncologists, immunologists, infectious disease specialists, intensivists, allied healthcare professionals and patients/parents, formulated relevant research questions and conducted a systematic literature review (SLR). Delphi methodology, informed by SLR results and questionnaires of experts, was used to generate statements aimed at assisting early decision-making and optimising the initial care of patients with HLH/MAS.

RESULTS

The task force developed 6 overarching statements and 24 specific points to consider relevant to early recognition of HLH/MAS, diagnostic approaches, initial management and monitoring of HLH/MAS. Major themes included the simultaneous need for prompt syndrome recognition, systematic evaluation of underlying contributors, early intervention targeting both hyperinflammation and likely contributors, careful monitoring for progression/complications and expert multidisciplinary assistance.

CONCLUSION

These 2022 EULAR/American College of Rheumatology points to consider provide up-to-date guidance, based on the best available published data and expert opinion. They are meant to help guide the initial evaluation, management and monitoring of patients with HLH/MAS in order to halt disease progression and prevent life-threatening immunopathology.

The 2022 EULAR/ACR points to consider at the early stages of diagnosis and management of suspected haemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS)

OBJECTIVE

Haemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening systemic hyperinflammatory syndromes that can develop in most inflammatory contexts. They can progress rapidly, and early identification and management are critical for preventing organ failure and mortality. This effort aimed to develop evidence-based and consensus-based points to consider to assist clinicians in optimising decision-making in the early stages of diagnosis, treatment and monitoring of HLH/MAS.

METHODS

A multinational, multidisciplinary task force of physician experts, including adult and paediatric rheumatologists, haematologist/oncologists, immunologists, infectious disease specialists, intensivists, allied healthcare professionals and patients/parents, formulated relevant research questions and conducted a systematic literature review (SLR). Delphi methodology, informed by SLR results and questionnaires of experts, was used to generate statements aimed at assisting early decision-making and optimising the initial care of patients with HLH/MAS.

RESULTS

The task force developed 6 overarching statements and 24 specific points to consider relevant to early recognition of HLH/MAS, diagnostic approaches, initial management and monitoring of HLH/MAS. Major themes included the simultaneous need for prompt syndrome recognition, systematic evaluation of underlying contributors, early intervention targeting both hyperinflammation and likely contributors, careful monitoring for progression/complications and expert multidisciplinary assistance.

CONCLUSION

These 2022 EULAR/American College of Rheumatology points to consider provide up-to-date guidance, based on the best available published data and expert opinion. They are meant to help guide the initial evaluation, management and monitoring of patients with HLH/MAS in order to halt disease progression and prevent life-threatening immunopathology.

Immunodeficiency with susceptibility to lymphoma with complex genotype affecting energy metabolism (FBP1, ACAD9) and vesicle trafficking (RAB27A)

Introduction

Inborn errors of immunity (IEI) are characterized by a dysfunction of the immune system leading to increased susceptibility to infections, impaired immune regulation and cancer. We present a unique consanguineous family with a history of Hodgkin lymphoma, impaired EBV control and a late onset hemophagocytic lymphohistiocytosis (HLH).

Methods and results

Overall, family members presented with variable impairment of NK cell and cytotoxic T cell degranulation and cytotoxicity. Exome sequencing identified homozygous variants in RAB27A, FBP1 (Fructose-1,6-bisphosphatase 1) and ACAD9 (Acyl-CoA dehydrogenase family member 9). Variants in RAB27A lead to Griscelli syndrome type 2, hypopigmentation and HLH predisposition.

Discussion

Lymphoma is frequently seen in patients with hypomorphic mutations of genes predisposing to HLH. We hypothesize that the variants in FBP1 and ACAD9 might aggravate the clinical and immune phenotype, influence serial killing and lytic granule polarization by CD8 T cells. Understanding of the interplay between the multiple variants identified by whole exome sequencing (WES) is essential for correct interpretation of the immune phenotype and important for critical treatment decisions.

Hemophagocytic Lymphohistiocytosis Associated With Polyserositis and Salmonella typhi Infection

Hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially fatal disease characterized by excessive immune response activation. Numerous conditions, including infectious etiologies, are implicated in its development. We report the case of a 16-year-old girl with HLH associated with polyserositis and Salmonella typhi infection. A 16-year-old girl presented with a high-grade fever and abdominal pain that had been ongoing for 20 days. She had been treated for malaria at a local hospital but was referred to our hospital due to the worsening of her condition. On examination, she was found to have an enlarged liver and spleen, pale skin, and hypotension, with bilateral basal crackles on chest examination. Her blood profile revealed pancytopenia, elevated C-reactive protein, and a deranged coagulation profile. Peripheral smears showed anisocytosis, microcytes, hypochromia in RBCs, and a few platelet clumps. A bone marrow biopsy revealed increased megakaryocytes and hemophagocytes. Ultrasound and computed tomography of the abdomen and pelvis showed hepatosplenomegaly, pericholecystic edema, mild ascites, and long-segment diffuse colonic wall thickening, suggesting pancolitis. Blood culture revealed S. typhi, which is rarely associated with HLH. The patient was started on the HLH-2004 protocol and showed improvement on the fourth day of initiating therapy, but due to a delayed diagnosis, the patient collapsed on the sixth day of admission. HLH is a rare but life-threatening disease with various underlying causes. The diagnosis of HLH is challenging, and early diagnosis and prompt treatment are crucial for a better prognosis. The association between HLH and S. typhi infection is rare, and this case highlights the importance of considering unusual etiologies in HLH. Clinicians should be vigilant about this association, especially in endemic regions, to ensure early diagnosis and prompt treatment.

Case report: Ruxolitinib plus dexamethasone as first-line therapy in haemophagocytic lymphohistiocytosis

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.

Case report: Virus-induced hemophagocytic lymphohistiocytosis in a patient with APECED

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.

18F-FDG PET/CT for Identifying the Potential Primary Diseases and Predicting Prognosis of Secondary Hemophagocytic Lymphohistiocytosis in Children

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal illness, which can be divided into primary HLH (pHLH) and secondary HLH (sHLH). pHLH can be driven by genetic defections. Moreover, the sHLH is usually be triggered by malignancy or non-malignancy diseases. Sixty-two newly diagnosed sHLH patients with known etiology and those who underwent ¹⁸F-FDG PET/CT examination from July 2018 to December 2020 were retrospectively analyzed. They were divided into malignancy-associated HLH (M-HLH, n = 13) and non-malignancy-associated HLH (NM-HLH, n = 49). The metabolic parameters of the liver (Li), spleen (Sp), bone marrow (BM), lymph nodes (LN), and their ratios to the liver background (LiBG) and mediastinum (M) were compared between two groups. These metabolic parameters were evaluated for correlation with laboratory parameters and prognostic parameters. We found that the SUV_max-LN/Sp/Li and SUV_mean-Sp in M-HLH were significantly higher than those in NM-HLH (P=0.031, 0.035, 0.016,  and 0.032). The malignant disease should be considered when SUVmax-LN was higher than 4.41 (sensitivity 61.5%, specificity 81.6%). Hypermetabolic lesions in extranodal organs were more likely to occur in M-HLH than in NM-HLH (P=0.011). IFN- γ was positively correlated with SUVmax-BM/Li/Sp and SUVmean-BM/Li/Sp (P < 0.05). Ferritin, sCD25, IL-6, and IL-10 were positively correlated with SUVmax-Sp and SUVmean-Sp (P < 0.05). In Epstein-Barr virus-associated HLH (EBV-HLH), the SUV parameters of bone marrow were significantly correlated with a poor 2-week treatment response, overall survival, and event-free survival (P < 0.05). We conclude that some ¹⁸F-FDG PET/CT metabolic parameters can help identify the etiology of sHLH in children and provide directions for further inspection. The malignant disease should be considered when the SUVmax-LN is higher than 4.41 and hypermetabolic lesions occur in extranodal organs. In EBV-HLH, a higher SUV of bone marrow is associated with a poorer prognosis.

The Role of Pre-therapeutic 18F-FDG PET/CT in Pediatric Hemophagocytic Lymphohistiocytosis With Epstein-Barr Virus Infection

Objective

To evaluate the role of pre-therapeutic ¹⁸F-FDG PET/CT in pediatric hemophagocytic lymphohistiocytosis (HLH) with Epstein-Barr virus (EBV) infection.

Methods

This retrospective study included 29 HLH children (1–16 years) with EBV infection, who underwent pre-therapeutic ¹⁸F-FDG PET/CT from July 2018 to November 2020. Pathology results were considered as the reference standard. These patients were divided into two groups: EBV-induced malignancy-associated HLH (M-HLH, N = 9) and EBV-induced non-malignancy-associated HLH (NM-HLH, N = 20). The regions of interest (ROIs) of the liver, spleen (Sp), bone marrow (BM), lymph nodes (LN), hypermetabolic lesions, liver background (LiBG), and mediastinum (M) were drawn with software 3D-Slicer. The volumetric and metabolic parameters, including maximum standard uptake value (SUV_max), metabolic tumor volume, and total lesion glycolysis of these ROIs, clinical parameters, and laboratory parameters were compared between the two groups. The efficiency of the above parameters in predicting the treatment response and overall survival (OS) was analyzed.

Results

Receiver operating characteristic curve analysis indicated that SUV_max-lesions and SUV_max-LN/M (AUC = 0.822, 0.819, cut-off = 6.04, 5.74, respectively) performed better in differentiating M-HLH from NM-HLH. It had the best diagnostic performance when age was added with the SUV_max-LN/M (AUC = 0.933, sensitivity = 100%, specificity = 85.0%). The presence of extranodal hypermetabolic lesions in multiple organs indicated the M-HLH (P = 0.022). Older age, higher SUV_max-LN and SUV_max-lesions, and the presence of serous effusion were associated with poorer treatment response at the 2nd and 4th week (not reaching partial remission). Multivariate analysis showed that SUV_max-lesions > 7.66 and SUV_max-Sp/LiBG > 2.01 were independent prognostic factors for overall survival (P = 0.025, 0.036, respectively).

Conclusions

¹⁸F-FDG PET/CT could be a valuable technique for identifying the underlying malignancy and predicting prognosis in pediatric HLH with EBV infection. M-HLH could be considered when SUV_max-lesions > 6.04, SUV_max-LN/M > 5.74, and the presence of extranodal hypermetabolic lesions in multiple organs on ¹⁸F-FDG PET/CT. SUV_max-lesions and SUV_max-Sp/LiBG might be independent prognostic factors for OS.

RF1 Gene Mutation in Familial Hemophagocytic Lymphohistiocytosis 2: A Family Report and Literature Review

OBJECTIVE

Gene mutation analysis was performed on a family with familial hemophagocytic lymphohistiocytosis (FHL) so as to provide an accurate etiological diagnosis, leading to genetic counseling for the family members.

METHODS

The clinical data of two probands (siblings) with FHL in one family were analyzed, and eight genes related to the onset of the primary hemophagocytic lymphohistiocytosis (pHLH) (PRF1, UNC13D, STX11, STXBP2, SH2D1A, BIRC4/XIAP, Rab27a, LYST) were detected and analyzed in the probands and their parents with whole exome sequencing.

RESULTS

Proband 1 was a two-year-old male with the clinical manifestations of fever, hepatosplenomegaly, and a decreased peripheral blood cell count, sCD25: 12504pg/mL. The results of genetic testing showed that there was a c.1349C>T heterozygous missense mutation and a c.853_855del heterozygous mutation in the PRF1 in proband 1. Proband 2 was an eight-year-old female with the clinical manifestations of convulsions and disturbance of consciousness with fever. The genetic test results were the same as those of proband 1. There was a single heterozygous mutation in the parents of the probands, and both probands had compound heterozygous mutations.

CONCLUSION

According to the clinical manifestations, laboratory tests, and results of the family molecular genetic testing, the probands could be clinically diagnosed as FHL2. The results of gene sequencing revealed that this was an autosomal recessive family with familial hemophagocytic syndrome. A rare pathogenic mutation (c.853_855del) in the PRF1 was discovered in the two patients with HLH.

Familial hemophagocytic lymphohistiocytosis in a neonate: Case report and literature review

RATIONALE

Familial hemophagocytic lymphohistiocytosis (FHL) is a potentially fatal disease that rarely presents in the neonatal period. Timely diagnosis is a key challenge owing to the atypical clinical manifestations. Here, we describe a case of FHL type 3 with disease onset in the early neonatal period and review the relevant literature. Our findings may provide insights into the diagnosis and treatment of this rare disease.

PATIENT CONCERNS

A 6-day-old male neonate presented with fever, hepatosplenomegaly, cytopenia, hyperferritinemia, hypofibrinogenemia, hemophagocytosis, and hypertriglyceridemia.

DIAGNOSIS

Considering the clinical picture (prolonged fever, progressive hepatosplenomegaly, high triglycerides, low fibrinogen, and high ferritin), along with abnormal natural killer-cell activity, combining sequence analysis of genomic DNA results (compound heterozygous mutations of UNC13D), the patient was finally diagnosed with FHL type 3 (FHL3).

INTERVENTIONS

The patient was initially treated with HLH-1994 protocol and subsequently switched to an oral regimen of ruxolitinib due to incomplete remission of the disease.

OUTCOMES

The trend of change in weekly cytokine levels, neutrophil counts, hemoglobin, and platelet counts indicated that the complete remission was not achieved after the treatment of HLH-1994 protocol. The platelet counts fluctuated within the normal range after oral administration of ruxolitinib. But soon after, the patient did not respond to treatment and eventually died of respiratory failure.

LESSON

Timely diagnosis of FHL is challenging. This case report illustrates that thrombocytopenia can be the first clinical sign of FHL with neonatal onset. Genetic testing, detection of cytokines, and flow cytometry should be performed as soon as possible to confirm the diagnosis. Given the high morbidity and mortality of FHL, pediatricians should have a high suspicion index for this disease.

MRI Patterns in Pediatric CNS Hemophagocytic Lymphohistiocytosis

BACKGROUND AND PURPOSE

Neuroimaging has an important role in detecting CNS involvement in children with systemic or CNS isolated hemophagocytic lymphohistiocytosis. We characterized a cohort of pediatric patients with CNS hemophagocytic lymphohistiocytosis focusing on neuroradiologic features and assessed whether distinct MR imaging patterns and genotype correlations can be recognized.

MATERIALS AND METHODS

We retrospectively enrolled consecutive pediatric patients diagnosed with hemophagocytic lymphohistiocytosis with CNS involvement treated at 2 pediatric neurology centers between 2010 and 2018. Clinical and MR imaging data were analyzed.

RESULTS

Fifty-seven children (40 primary, 70%) with a median age of 36 months (interquartile range, 5.5-80.8 months) were included. One hundred twenty-three MR imaging studies were assessed, and 2 broad imaging patterns were identified. Pattern 1 (significant parenchymal disease, 32/57, 56%) was seen in older children (P = .004) with worse clinical profiles. It had 3 onset subpatterns: multifocal white matter lesions (21/32, 66%), brainstem predominant disease (5, 15%), and cerebellitis (6, 19%). All patients with the brainstem pattern failed to meet the radiologic criteria for chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids. An attenuated imaging phenotype (pattern 2) was seen in 25 patients (44%, 30 studies) and was associated with younger age.

CONCLUSIONS

Distinct MR imaging patterns correlating with clinical phenotypes and possible genetic underpinnings were recognized in this cohort of pediatric CNS hemophagocytic lymphohistiocytosis. Disruptive mutations and missense mutations with absent protein expression correlate with a younger onset age. Children with brainstem and cerebellitis patterns and a negative etiologic work-up require directed assessment for CNS hemophagocytic lymphohistiocytosis.

Epstein-Barr Virus-Associated T- and NK-Cell Lymphoproliferative Diseases: A Review of Clinical and Pathological Features

Simple Summary

In most Epstein–Barr virus (EBV)-infected individuals, the virus establishes a lifelong latent infection with no specific clinical manifestation. However, EBV primary infection and secondary reactivation may cause various EBV-associated lymphoproliferative disorders (LPD), including hematologic malignancies. Among them, EBV-positive T/NK LPD are uncommon diseases defined by the proliferation of T- or NK-cells infected by EBV, more commonly encountered in Asians and Latin Americans. They encompass a spectrum of disorders ranging from indolent reactive lesions to malignant and aggressive diseases. Despite novel insights from high-throughput molecular studies, the pathogenesis of these disorders is not well understood, and EBV-positive T/NK LPD diagnoses remain challenging due to their rarity and considerable overlap. Indeed, this article discusses new insights into EBV-positive T/NK LPD and focuses on diagnosis challenges, describing the difficulties to clarify the borders between overlapping LPD subtypes.

Abstract

Epstein–Barr virus (EBV) is a ubiquitous virus detected in up to 95% of the general population. Most people are asymptomatic, while some may develop a wide range of EBV-associated lymphoproliferative disorders (LPD). Among them, EBV-positive T/NK LPD are uncommon diseases defined by the proliferation of T- or NK-cells infected by EBV. The 2017 World Health Organization (WHO) classification recognizes the following entities characterized by different outcomes: chronic active EBV infection of T- or NK-cell types (cutaneous and systemic forms), systemic EBV-positive T-cell lymphoma of childhood, EBV-positive aggressive NK-cell leukemia, extra nodal NK/T-cell lymphoma nasal type, and the new provisional entity known as primary EBV-positive nodal T/NK-cell lymphoma. In addition, EBV associated-hemophagocytic lymphohistiocytosis is part of EBV-positive T/NK LPD, but has not been included in the WHO classification due to its reactive nature. Despite novel insights from high-throughput molecular studies, EBV-positive NK/T-cell LPD diagnoses remain challenging, especially because of their rarity and overlap. Until now, an accurate EBV-positive NK/T LPD diagnosis has been based on its clinical presentation and course correlated with its histological features. This review aims to summarize clinical, pathological and molecular features of EBV-positive T/NK LPD subtypes and to provide an overview of new understandings regarding these rare disorders.

Ruxolitinib is an alternative to etoposide for patient with hemophagocytic lymphohistiocytosis complicated by acute renal injury: A case report

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by excessive production of inflammatory cytokines and multiple organs injury. Ruxolitinib, an oral selective JAK1/2 inhibitor, has recently shown efficacy and safety in the treatment of secondary HLH, which may be an alternative to intensive chemotherapy.

CASE REPORT

We report a case of a 2-year-old boy who presented to our institution with recurrent fever and acute renal failure. We made the diagnosis of Epstein-Barr virus related HLH based on the HLH-2004 protocol, and gave the treatment of ruxolitinib instead of etoposide.

MANAGEMENT AND OUTCOME

The patient received dexamethasone and continuous renal replacement therapy due to renal failure, but he still had fever and anuria. Given that the use of etoposide may deteriorate renal function, ruxolitinib was administered instead of etoposide. After 5 days of ruxolitinib treatment, the patient's fever was resolved and renal function also gradually recovered 14 days later.

DISCUSSION

Currently, dexamethasone, etoposide and cyclosporine A are the main drugs in HLH treatment. However, cytotoxic chemotherapy can temporally deteriorate organ damage and induce serious myelosuppression, which makes clinicians hesitate to implement these regimens. Ruxolitinib has shown efficacy in treating HLH without much toxicity in clinical trials. Thus, we suggest that ruxolitinib constitutes a treatment option for secondary HLH complicated by severe renal damage which may reduce toxic effects compared with intense chemotherapy.

Pediatric Fibrinogen PART II-Overview of Indications for Fibrinogen Use in Critically Ill Children

Bleeding is frequently seen in critically ill children and is associated with increased morbidity and mortality. Fibrinogen is an essential coagulation factor for hemostasis and hypofibrinogenemia is an important risk factor for bleeding in pediatric and adult settings. Cryoprecipitate and fibrinogen concentrate are often given to critically ill children to prevent bleeding and improve fibrinogen levels, especially in the setting of surgery, trauma, leukemia, disseminated intravascular coagulopathy, and liver failure. The theoretical benefit of fibrinogen supplementation to treat hypofibrinogenemia appears obvious, yet the evidence to support fibrinogen supplementation in children is sparce and clinical indications are poorly defined. In addition, it is unknown what the optimal fibrinogen replacement product is in children and neonates or what the targets of treatment should be. As a result, there is considerable variability in practice. In this article we will review the current pediatric and applicable adult literature with regard to the use of fibrinogen replacement in different pediatric critical care contexts. We will discuss the clinical indications for fibrinogen supplementation in critically ill children and the evidence to support their use. We summarize by highlighting current knowledge gaps and areas for future research.

Outcomes and prognostic factors associated with 180-day mortality in Taiwanese pediatric patients with Hemophagocytic Lymphohistiocytosis

BACKGROUND/PURPOSE

Hemophagocytic lymphohistiocytosis (HLH), a rarely occurring syndrome with various triggers, is associated with early mortality. Owing to a lack of sufficient corresponding data in Taiwan, this study aimed to identify the outcome and potential factors associated with 180-day mortality in pediatric HLH.

METHODS

This retrospective study analyzed clinical and laboratory data on pediatric patients diagnosed with HLH at our institute (1995-2019). Logistic regression analysis was conducted to determine the associations between various factors and 180-day mortality.

RESULTS

Overall, 48 patients had HLH; their median age at diagnosis was 5 years (interquartile range: 2-11 years). Clinical presentations and laboratory parameters required for diagnosis included fever (98%), splenomegaly (79%), hyperferritinemia (98%), hemophagocytosis (94%), thrombocytopenia (90%), anemia (63%), hypertriglyceridemia (68%), and neutropenia (57%). The 5-year overall survival (OS) rate was 49%. Of 22 patients who had died at the last follow-up, 15 (68%) died within 180 days after diagnosis. In the multivariate analysis, hemoglobin (odds ratio [OR]: 0.564, p = 0.024) and triglyceride (OR: 1.004, p = 0.049) were significantly associated with 180-day mortality. Higher triglyceride levels at diagnosis were related to significantly lower 180-day OS rates (52.9% vs. 86.1%, p = 0.018).

CONCLUSION

The overall outcome in our cohort was similar to that reported in some of the largest international cohorts. Hypertriglyceridemia and anemia may be indicative of poor prognoses in pediatric HLH patients independently and may be used to guide treatment strategy formulations for better outcomes.

Epstein-Barr Virus Versus Novel Coronavirus-Induced Hemophagocytic Lymphohistocytosis: The Uncharted Waters

Hemophagocytic lymphohistocytosis (HLH) is a hyperinflammatory syndrome characterized by fever, hepatosplenomegaly, and pancytopenia. It may be associated with genetic mutations or viral/bacterial infections, most commonly Epstein-Barr virus (EBV) and cytomegalovirus. As for the novel coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), also known as COVID-19 (coronavirus disease-2019), the cytokine storm it triggers can theoretically lead to syndromes similar to HLH. In this article, we report a case of a 28-year-old female who presented with high-grade fevers, found to have both SARS-CoV-2 and EBV infections, and eventually began to show signs of early HLH. To our knowledge, this is the first case reported in literature that raises the possibility of SARS-CoV-2–related HLH development.

Clinico-laboratory profile and perforin gene mutations of pediatric hemophagocytic lymphohistiocytosis cases: a five-year single center study

Introduction

hemophagocytic lymphohistiocytosis (HLH) is an immunological disease characterized by hemophagocytosis of blood cells and proliferation of T-cells and histiocytes in the spleen and bone marrow then infiltration into body organs. Familial HLH (FHL) is a fatal disorder and determining gene mutations is a good guide for predicting the prognosis and choosing treatment options. This study aimed to illustrate the clinical, laboratory characteristics, including perforin gene mutation screening, treatment and survival outcome of pediatric HLH patients.

Methods

we conducted this cross-sectional study on pediatric patients who were diagnosed with HLH using the revised HLH-2004 criteria, from January 2014 to February 2019 at Zagazig University Children's Hospital, Egypt. We collected demographic, clinical and laboratory data and screened for the presence of mutations in perforin (PRF1) gene by polymerase chain reaction (PCR) amplification. We treated the patients according to HLH-2004 treatment protocol and documented their survival outcome.

Results

the total number of cases were 18; eight males and ten females, the age range was between three months and 12 years. Of the eight HLH-2004 diagnostic criteria, all patients met at least five criteria. We detected PRF1 gene mutation in 38.9% (7 patients) with nine previously unreported mutations. Sixteen patients (88.9%) received HLH-2004 treatment protocol and the remaining two patients died before initiation of treatment. The overall mortality was 72.2% (13 patients).

Conclusion

our results increase the awareness of clinical and laboratory characterizations of pediatric HLH patients and the prevalence of PRF1 gene mutations among those patients.

Treatment of pediatric primary hemophagocytic lymphohistiocytosis with the HLH-94/2004 regimens and hematopoietic stem cell transplantation in China

We aimed to clarify the clinical characteristics, prognostic factors, and effectiveness of the HLH-94/2004 regimens and hematopoietic stem cell transplantation (HSCT) in pediatric patients with primary hemophagocytic lymphohistiocytosis (pHLH) in China. A retrospective analysis was performed on 38 patients with pHLH at Beijing Children's Hospital. PRF1 (34.2%) and UNC13D (31.6%) were the most common mutations in the pHLH. Thirty-eight patients were treated with the HLH-94/2004 regimens after diagnosis. Twenty-six patients (72.2%) responded to first-line treatment (complete response: 55.5%, partial response: 16.7%). The median survival time was 23 months. The overall survival (OS) rate at 3 years was 74.7%. There was no significant difference in the response rate (72% vs. 63.6%, P = 0.703) or 3-year OS (83.6% vs. 66.7%, P = 0.443) between the patients treated with the HLH-94 regimen and those treated with the HLH-2004 regimen. The incidences of all side effects in patients treated with the HLH-94 or HLH-2004 regimen were 32.0% and 18.2%, respectively (P = 0.394). Among 15 patients treated with HSCT, neither the preconditioning regimen nor the donor type affected patient prognosis (P = 0.205 and P = 0.161, respectively). The disease status (remission or nonremission) before preconditioning did not affect prognosis or the incidence of GVHD. Furthermore, a higher bilirubin level (≥ 30 μmol/L) was correlated with a poorer prognosis in pHLH patients (P = 0.026). The effectiveness rates of the HLH-94 and HLH-2004 regimens, chemotherapy, and HSCT were similar in pHLH patients. A bilirubin level ≥ 30 μmol/L might be an adverse prognostic factor in pHLH.

Dilemmas in diagnosis and management of hemophagocytic lymphohistiocytosis in children

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening entity which is characterized by severe hyperinflammation. Now the HLH-2004 protocol has been widely accepted and clinically used; however, many questions still remain in clinical practice. In this review, we discuss the dilemmas in the diagnosis and treatment of HLH in children.

DATA SOURCES

Original research for articles and literature reviews published in PubMed was carried out using the key term "hemophagocytic lymphohistiocytosis".

RESULTS

As the gene sequencing technology progresses, the range of causal mutations and primary HLH has been redefined. The monoallelic variants may contribute to the pathogenesis of the disease. Many conditions without defective cytotoxicity of T or NK cells may lead to HLH, such as primary immunodeficiency (PID) and dysregulated immune activation or proliferation (DIAP). HLH shares overlapping clinical and laboratory characteristics with severe sepsis, but usually the single values are more pronounced in HLH than sepsis. H score is another approach to help the diagnosis of secondary HLH. Specific Th1/Th2 cytokine patterns are very helpful tools to differentiate HLH (reactivation of HLH) from sepsis. Moreover, it also has been used successfully to stratify the therapy intensity. The treatment of HLH should consider underlying diseases, triggers and severity. HLH-94 is recommended for patients who need etoposide-based therapy.

CONCLUSIONS

Dramatic progress has been made during the past decades in understanding the pathophysiology of HLH. However, diagnosis and treatment of HLH remain with many dilemmas because of the heterogeneous nature of the disease. Better understanding new gene defects and more effective diagnostic approaches and salvage regimens are goals for the future.

Hemophagocytic Lymphohistiocytosis in Children: Clinical Profile and Outcome

OBJECTIVES

The objectives of this study were to describe the clinical and etiologic profile and outcomes of children with hemophagocytic lymphohistiocytosis (HLH) in a tertiary care hospital in South India.

METHODS

This is a combined 2-year prospective (2017 to 2018) and 5-year retrospective (2012 to 2016) descriptive study in which children from birth to 18 years who satisfied the HLH-2004 diagnostic criteria were included. Case details from patient records were analyzed.

RESULTS

Fifty-three cases were enrolled of which 20 were prospective and 33 were retrospective. Fever, hepatomegaly, anemia, and hyperferritinemia were the common presentations. Infectious triggers were found in 33 (62%) cases. Five cases were secondary to rheumatic diseases, and 8 were primary HLH. Bacterial (14 cases) followed by viral infections (10 cases) were the leading triggers. Scrub typhus (6 cases) and dengue (4 cases) were the most common infectious agents. Major complications include febrile neutropenia (38%) and multiorgan dysfunction (26%). One child developed secondary malignancy. The most frequently used immunosuppressive drug for the treatment of HLH was steroid (70%), while 28% of cases recovered with only supportive therapy. The overall mortality was 41%.

CONCLUSIONS

Infections were the most common triggers for HLH of which tropical infectious agents constituted the majority. Treatment with steroids alone or regimens without cytotoxic drugs may result in resolution of secondary HLH with mild to moderate disease activity. Without stem cell transplant, primary HLH has a high mortality rate.

[A genetic analysis of children with Epstein-Barr virus-positive hemophagocytic lymphohistiocytosis and its association with T-helper type 1/T-helper type 2 cytokines]

OBJECTIVE

To study the effect of genetic variation on the prognosis of children with Epstein-Barr virus (EBV)-positive hemophagocytic lymphohistiocytosis (HLH) and its association with cytokines.

METHODS

A total of 81 EBV-positive HLH children who received the sequencing of related genes were enrolled. According to the results of gene detection, they were divided into a non-mutation group and a mutation group. According to the pattern of gene mutation, the mutation group was further divided into three subgroups: single heterozygous mutation (SHM), double heterozygous mutation (DHM), and homozygous or compound heterozygous mutation (H-CHM). The serum levels of cytokines were measured and their association with HLH gene mutations was analyzed.

RESULTS

UNC13D gene mutation had the highest frequency (13/46, 28%). The STXBP2 c.575G>A(p.R192H) and UNC13D c.604C>A(p.L202M) mutations (likely pathogenic) were reported for the first time. The mutation group had a significantly higher level of tumor necrosis factor alpha (TNF-α) than the non-mutation group, while it had a significantly lower level of interferon gamma (IFN-γ) than the non-mutation group (P<0.05). The IL-4 level of the DHM subgroup was higher than that of the non-mutation group, while the IL-4 level of the H-CHM subgroup was lower than that of the DHM group (P<0.0083). The H-CHM subgroup had a significantly lower 1-year overall survival rate than the non-mutation group, the SHM subgroup, and the DHM subgroup (39%±15% vs 85%±6%/86%±7%/91%±9%, P=0.001).

CONCLUSIONS

There is a significant reduction in IFN-γ level in the mutation group. Children with homozygous or compound heterozygous mutation tend to have poorer prognosis, while other mutations do not have a significant impact on prognosis.

Outcome analysis of pediatric hemophagocytic lymphohistiocytosis

PURPOSE

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease associated with rapid clinical deterioration and the need for intensive care; therefore, it is essential to identify clinical parameters related to mortality and establish prognostic factors correlated with unfavorable outcome in high risk patients whose treatment may fail.

METHODS

Between January 2004 and December 2018, a total of 51 pediatric patients (less than 18 years old) who fulfilled the diagnostic criteria of HLH-2004 with documented results of bone marrow investigations at Kaohsiung Chang Gung Memorial Hospital were enrolled. The treatment protocol was based on hemophagocytic lymphohistiocytosis-94 (HLH-94) and HLH-2004. We retrospectively reviewed electronic medical records (EMR) including clinical features, length of intensive care unit (ICU) stay, serological tests, microscopic reports of bone marrow examination, and ultrasound examination reports at diagnosis to identify prognostic factors. The patients were divided into four groups based on etiology; these included infection associated hemophagocytic syndrome (IAHS), macrophage activation syndrome (MAS), malignancy associated hemophagocytic lymphohistiocytosis (MA-HLH), and idiopathic hemophagocytic lymphohistiocytosis (IHLH) to identify differences among the groups.

RESULTS

Out of 51 patients enrolled, 27 patients had IAHS, 12 MAS, 8 MA-HLH, and 4 IHLH. The median age at diagnosis was 7 years. The overall mortality rate was 15.7% (there was no mortality in the MA-HLH group); the mean length of ICU stay was 6 ± 20.8 days. Longer activated partial thromboplastin time (aPTT) (p = 0.007), lower sodium concentration (p = 0.0007), and higher creatinine (p = 0.032) and aspartate aminotransferase (AST) (p = 0.017) were significantly related to mortality. Multivariate Cox regression analysis demonstrated that aPTT (p = 0.045, HR = 1.03, 95% CI = 1.0-1.1) was an independent risk factor for mortality. The receiver operating characteristic (ROC) curve showed that aPTT longer than 44.35 s was the cutoff value predicting mortality, with a sensitivity and specificity of 72% and 66.7%, respectively.

CONCLUSION

MA-HLH had the lowest mortality rate, as most children died from the underlying malignant disease and not from HLH. Impaired liver and renal functions were related to mortality. Prolonged aPTT > 44.35 s is a strong predictive factor for mortality.

FHLdb: A Comprehensive Database on the Molecular Basis of Familial Hemophagocytic Lymphohistiocytosis

Background: Primary immunodeficiencies (PIDs) are a heterogeneous group of disorders. The lack of comprehensive disease-specific mutation databases may hinder or delay classification of the genetic variants found in samples from these patients. This is especially true for familial hemophagocytic lymphohistiocytosis (FHL), a life-threatening PID classically considered an autosomal recessive condition, but with increasingly demonstrated genetic heterogeneity.

Objective: The aim of this study was to build an open-access repository to collect detailed information on the known genetic variants reported in FHL.

Methods: We manually reviewed more than 120 articles to identify all reported variants related to FHL. We retrieved relevant information about the allelic status, the number of patients with the same variant, and whether functional assays were done. We stored all the data retrieved in a PostgreSQL database and then built a website on top of it, using the Django framework.

Results: The database designed (FHLdb) (https://www.biotoclin.org/FHLdb) contains comprehensive information on reported variants in the 4 genes related to FHL (PRF1, UNC13D, STXBP2, STX11). It comprises 240 missense, 69 frameshift, 51 nonsense, 51 splicing, 10 in-frame indel, 7 deep intronic, and 5 large rearrangement variants together with their allelic status, carrier(s) information, and functional evidence. All genetic variants have been classified as pathogenic, likely pathogenic, uncertain significance, likely benign or benign, according to the American College of Medical Genetics guidelines. Additionally, it integrates information from other relevant databases: clinical evidence from ClinVar and UniProt, population allele frequency from ExAC and gnomAD, and pathogenicity predictions from well-recognized tools (e.g., PolyPhen-2, SIFT). Finally, a diagram depicts the location of the variant relative to the gene exon and protein domain structures.

Conclusion: FHLdb includes a broad range of data on the reported genetic variants in familial HLH genes. It is a free-access and easy-to-use resource that will facilitate the interpretation of molecular results of FHL patients, and it illustrates the potential value of disease-specific databases for other PIDs.

Hermansky-Pudlak syndrome: Mutation update

Hermansky-Pudlak syndrome (HPS) is a group of 10 autosomal recessive multisystem disorders, each defined by the deficiency of a specific gene. HPS-associated genes encode components of four ubiquitously expressed protein complexes: Adaptor protein-3 (AP-3) and biogenesis of lysosome-related organelles complex-1 (BLOC-1) through -3. All individuals with HPS exhibit albinism and a bleeding diathesis; additional features occur depending on the defective protein complex. Pulmonary fibrosis is associated with AP-3 and BLOC-3 deficiency, immunodeficiency with AP-3 defects, and gastrointestinal symptoms are more prevalent and severe in BLOC-3 deficiency. Therefore, identification of the HPS subtype is valuable for prognosis, clinical management, and treatment options. The prevalence of HPS is estimated at 1-9 per 1,000,000. Here we summarize 264 reported and novel variants in 10 HPS genes and estimate that ~333 Puerto Rican HPS subjects and ~385 with other ethnicities are reported to date. We provide pathogenicity predictions for missense and splice site variants and list variants with high minor allele frequencies. Current cellular and clinical aspects of HPS are also summarized. This review can serve as a manifest for molecular diagnostics and genetic counseling aspects of HPS.

Molecular analysis of the novel L243R mutation in STXBP2 reveals impairment of degranulation activity

The presence of mutations in PRF1, UNC13D, STX11 and STXBP2 genes in homozygosis or compound heterozygosis results in immune deregulation. Most such cases lead to clinical manifestations of haemophagocytic lymphohistiocytosis (HLH). In the present study, we analyzed degranulation and cytotoxicity in a pediatric patient with a late presentation of HLH associated with Epstein-Barr virus infection. Remarkably, the results of the degranulation assay showed reduction of CD107a median fluorescence intensity (MFI) and absent cytotoxicity. Genetic analysis identified compound heterozygous mutations in STXBP2 gene: a previously reported splicing defect in exon 15 (c.1247-1G>C, p.V417LfsX126) and a novel missense mutation in exon 9 (c.728T>G, p.L243R). Transfection experiments of STXBP2-L243R or STXBP2-WT constructs showed an undetectable protein expression of the STXBP2-L243R mutation. The residue L243 is highly preserved evolutionarily; moreover, computational analysis of its structure revealed its participation in the rich network of interactions that stabilizes domains 2 and 3 of the protein. Altogether, we demonstrated by molecular and in silico analysis that the new L243R mutation in STXBP2 plays a pathogenic role that, together with the p.Val417Leufsc mutation, shows the synergistic negative effect of these two mutations on STXBP2 function, leading to a decrease of degranulatory activity in vivo.

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

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

Genetic characterization of pediatric primary hemophagocytic lymphohistiocytosis in China: a single-center study

To study the genetic characteristics of primary hemophagocytic lymphohistiocytosis (pHLH) in China, we investigated the genetic data and clinical features of Chinese HLH patients. We retrospectively reviewed the genetic and clinical data of patients with HLH from November 2015 to June 2018. As a result, 26 patients were diagnosed with pHLH. The median age at diagnosis was 2.8 years (range 0.1-13.7 years). The probable overall survival at 12 and 24 months was 87.6% and 62.6%, respectively. Mutations in PRF1 (38.4%) and UNC13D (26.9%) were the most common genetic abnormalities. Furthermore, we identified 19 novel mutations that had not been previously reported and were predicted to likely be pathogenic. In addition to HLH-associated genes, there were 27 other genes identified. Genotype-phenotype analysis showed that patients with disruptive mutations were significantly younger at diagnosis than those with other mutation types (2.9 years vs. 6.4 years, P = 0.036). Familial HLH patients were more prone to central nervous system involvement and seizures compared with other patients (83.3% vs. 37.5%, P = 0.019; 55.6% vs. 12.5%, P = 0.04, respectively). In summary, numerous new mutations in HLH-related genes and other genes were identified in Chinese children with pHLH. Significantly, disruptive mutation types were more likely to be found in younger patients, and familial HLH patients tended to exhibit central nervous system involvement and seizures.

Pathogenic Gene Mutations or Variants Identified by Targeted Gene Sequencing in Adults With Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) can be classified into primary HLH and secondary HLH. Primary HLH usually occurs in infants and children with an underlying genetic defect, and there are also teens and occasional adults with primary HLH. Most cases with secondary HLH are adult patients with secondary triggers including infections, malignancies, and autoimmune diseases. The distinction between primary HLH and secondary HLH seems to be less straightforward, as patients with secondary HLH may also have genetic defects while primary HLH can be triggered by secondary causes. In this study, using amplicon-based targeted gene sequencing (TGS), we sequenced eighteen HLH-related genes in 112 adult HLH cases, which were mostly secondary HLH. Mutations or rare variants were identified in 48 cases (42.9%). All the variants except one were missense variants, and biallelic gene mutations were identified in 3 cases in which only one case harbored homogenous missense mutation. Recurrent variants including UNC13D p.G863D and AP3B1 p.T359A are much more prevalent in our cohort than in normal East Asian population, and in silico analysis predicted pathogenicity of these variants. In conclusion, according to our study, genetic defects may also contribute to the development of adult HLH cases or secondary HLH cases.

Secondary hemophagocytic lymphohistiocytosis in pediatric patients: a single center experience and factors that influenced patient prognosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome of excessive immune activation. Secondary HLH syndrome develops as a complication of infection, drugs, rheumatologic conditions, or malignancy. The main objectives of this work were to identify the etiology of secondary HLH and prognostic factors associated with mortality. Patients diagnosed with secondary HLH, between January 2011 and December 2016, were retrospectively included in this study. We analyzed clinical and laboratory findings as well as prognostic factors from 24 pediatric patients diagnosed with secondary HLH. The mean age of patients at the time of diagnosis was 79.9 ± 68.7 months (range: 2-202) and 54.2% of the patients were male. The most frequent HLH-2004 criterion was fever (100%). Underlying triggers of HLH were as follows: 13 (54.1%) infections, juvenile idiopathic arthritis in 5 patients (20.8%), drugs in 3 patients (12.5%), malignancies in 2 (0.8%), Kawasaki disease in 1 (0.4%) patient, and 1 (0.4%) with unknown triggers. The median time of diagnosis was 3 days (1-67 days). Overall, the mortality rate was 20.8%. In our logistic regression model, factors associated with mortality were decreased albumin levels (OR1 = 2.3[1.48-3.43]) and etoposide usage (OR2 = 1.22 [1.14-1.89]). The patient's 30-day survival was inferior among patients whose albumin level was 2 g/dL or less compared to those over 2 g/dL. Increased awareness of the underlying condition is critical in HLH patients. Our study emphasizes the prognostic significance of albumin level.

Epstein-Barr Virus-Associated T and NK-Cell Lymphoproliferative Diseases

EBV-associated T and NK-cell lymphoproliferative diseases (EBV-T/NK LPDs) are characterized by the transformation and proliferation of EBV-infected T or NK cells. The 2016 revised World Health Organization classification recognizes the following EBV-positive lymphoproliferative disorders (LPD): chronic active EBV infection (CAEBV) of T- and NK-cell type (cutaneous and systemic forms), systemic EBV-positive T-cell lymphoma of childhood, aggressive NK-cell leukemia, extranodal NK/T-cell lymphoma, nasal type, and the new provisional entity primary EBV-positive nodal T/NK-cell lymphoma. EBV-associated hemophagocytic lymphohistiocytosis (HLH), although not included in the WHO classification because it is a reactive, inflammatory disease, is included in this review because it can be life-threatening and may have overlapping features with other EBV+ T/NK LPDs. EBV+ T/NK LPDs are rare diseases difficult to diagnose and manage properly, because some LPDs have unusual presentations, and discrepancies between clinical and histological findings might be encountered. Furthermore, EBV+ T/NK disorders share some clinico-pathological features, and may evolve into other categories during the clinical course, including malignant transformation of CAEBV. Here, we review the EBV+ T/NK LPDs in terms of their definitions, clinical features, histology, immunophenotype, molecular findings, and pathogenesis. This review aims to increase our understanding and awareness of the differential diagnosis among the different EBV+ T/NK LPDs. New insights into the genetic characteristics of these disorders will also be discussed.

What's in a name? The heterogeneous clinical spectrum and prognostic factors in a cohort of adults with hemophagocytic lymphohistiocytosis

PURPOSE

Hemophagocytic lymphohistiocytosis (HLH) in adults is rare but frequently fatal. Diagnosis is often delayed and treatment approaches vary significantly in contrast to the protocol-driven approach typically used in pediatric HLH. To improve care of these complex patients, this study retrospectively examined the prevalence, clinical characteristics, therapies and outcomes of adult HLH patients at two large tertiary care centers.

METHODS

Adult patients with HLH confirmed by retrospective review of electronic medical records using HLH2004 criteria during admissions to the University of Texas Southwestern and Parkland Memorial Hospitals between June 2007 and June 2017 were studied.

RESULTS

Of 31 patients included, 67.7% were male with mean age of 46 years. Average time from admission to diagnosis was 10.5 days. 48% of patients had malignancy, with T-cell lymphoma being most common. Infections were seen in 70%. Autoimmune disorders were found in 9.6%. In total, 13 patients survived (44.8%). Median survival was 8 months with increased mortality in malignancy-associated HLH (median 0.56 months versus 36.5 months, p < 0.001). T-cell lymphoma carried a worse prognosis than other malignancies. Central nervous system disease, hypoalbuminemia, elevated bilirubin, elevated soluble interleukin 2 receptor, and elevated lactate dehydrogenase, were also associated with poor survival. Treatment varied significantly. No individual treatment improved survival.

CONCLUSION

This study corroborates prior limited data in adult HLH patients regarding poor survival, particularly in malignancy-associated HLH. Earlier recognition of this disease and a multidisciplinary approach to streamline diagnosis and optimize treatment are needed to improve outcomes in adult HLH patients.

Hemophagocytic lymphohistiocytosis and congenital factor VII deficiency: a case report

Background

Hemophagocytic lymfohistiocytosis (HLH) is a rare, life-threatening hyperinflammation, characterized by immune system over-activation resulting in hemophagocytosis. HLH could appear as a primary disease caused by mutations of immune-regulatory genes, or develop as a result of viral or bacterial infections, or malignancy. Congenital factor VII (FVII) deficiency is a rare autosomal recessive disorder characterized by prolonged prothrombin time (PT) and low FVII, which may increase bleeding risk.

Case presentation

A 50-year-old woman was admitted for a fever persisted for 20 days, presenting with cytopenia, high hyperferritinemia, low activity of NK cells. Bone marrow aspiration showed hemophagocytosis. CT scanning found pulmonary infection. EBV and CMV were not detected. Genetic scanning did not find pathogenic mutation of a HLH NGS panel including 26 genes. This patient was treated as recommended by the HLH 2004 Guidelines. Coagulation tests identified FVII deficiency. Genetic analysis of F7 gene in the patient and her family members identified recurrent compound heterozygous F7 c.64 + 5G > A and c.1224 T > G (p.His408Gln) mutations in this patient and her brother who showed postoperative hemorrhage after surgical resection of renal cell carcinoma. Heterozygotes in this family were asymptomatic.

Conclusions

To our knowledge, this is the first report of HLH in combination with congenital FVII deficiency in Chinese population.

Comparing hemophagocytic lymphohistiocytosis in pediatric and adult patients

PURPOSE OF REVIEW

Hemophagocytic lymphohistiocytosis (HLH) has long been thought of primarily as a pediatric disease. However, this syndrome may occur secondary to underlying malignancies, infections, and autoimmune diseases, in adult patients. Here, we seek to highlight similarities and differences between pediatric and adult HLH, knowledge gaps, and areas of active research.

RECENT FINDINGS

Malignancy is a more frequent driver of HLH in adults, present in nearly half. Prognosis is poor as compared with nonmalignant HLH. Prognosis in adults is generally worse than pediatric patients, suggesting that age and other comorbid illnesses not surprisingly affect the outcome of HLH. Diagnostic and treatment approaches are more variable in adults, likely contributing to poorer outcomes. The frequency of mutations in HLH-causing genes is higher than had been anticipated in adults, although with a higher frequency of uniallelic and hypomorphic mutations than in children.

SUMMARY

Optimizing diagnostic criteria for earlier detection may benefit both children and adults. Standardizing treatment approaches in adults will be more difficult because of the variability in triggering illnesses, but a more standardized or algorithmic approach will likely be beneficial. More research into the role of uniallelic and hypomorphic mutations in adults is necessary, to understand treatment and prognostic implications.

Genetic variant spectrum in 265 Chinese patients with hemophagocytic lymphohistiocytosis: Molecular analyses of PRF1, UNC13D, STX11, STXBP2, SH2D1A, and XIAP

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening hyperinflammatory disease. This study aimed to investigate the frequencies and distributions of inherited variants in PRF1, UNC13D, STX11, STXBP2, SH2D1A, and XIAP genes in Chinese patients with HLH. A total of 265 patients diagnosed with HLH from January, 2010 to December, 2016 were recruited and analyzed for the 6 genes. Genetic variants were observed in 87 (32.83%) patients. 36 (13.58%) exhibited variants in UNC13D, 18 (6.79%) exhibited PRF1 variants, 10 (3.77%) had variants in XIAP, 9 (3.40%) exhibited variants in STXBP2, 6 (2.26%) carried variants in SH2D1A, 1 (0.38%) had STX11 variant, and 7 (2.64%) exhibited digenic variants. Monoallelic variants were the most common, which accounted for 49.43% of all cases with variants. All variants were confirmed to be germline-derived. The present study describes a distinct variant spectrum in Chinese patients with HLH, whereby UNC13D is the most frequently mutated gene with missense variants that are the most common molecular defects. The variant profile of Chinese HLH patients is quite different from that of Western cohorts but similar to that of Korean patients, yet showing its own uniqueness. This racial difference shows the role of genetic background in the occurrence of HLH.

Epstein-Barr Virus and Hemophagocytic Lymphohistiocytosis

Epstein–Barr virus (EBV) is a ubiquitous virus that infects nearly all people worldwide without serious sequela. However, for patients who have genetic diseases which predispose them to the development of hemophagocytic lymphohistiocytosis (HLH), EBV infection is a life-threatening problem. As a part of a themed collection of articles on EBV infection and human primary immune deficiencies, we will review key concepts related to the understanding and treatment of HLH.

Proliferation through activation: hemophagocytic lymphohistiocytosis in hematologic malignancy

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of cytokine-driven immune activation. Cardinal features include fever, hemophagocytosis, hepatosplenomegaly, lymphocytic infiltration, and hypercytokinemia that result in multisystem organ dysfunction and failure. Familial HLH is genetically driven, whereas secondary HLH (SHL) is caused by drugs, autoimmune disease, infection, or cancer. SHL is associated with worse outcomes, with a median overall survival typically of less than 1 year. This reflects difficulty in both diagnostic accuracy and in establishing reliable treatments, especially in cases of malignancy-induced SHL, which have significantly worse outcomes. Malignancy-induced HLH is seen almost exclusively with hematologic malignancies, constituting 97% of cases in the literature over the past 2 years. In these situations, the native immune response driven by CD8 T cells produces an overabundance of T helper 1 cytokines, notably interferon-γ, tumor necrosis factor-α, and interleukin-6, which establish a positive feedback loop of inflammation, enhancing replication of hematologic malignancies while leaving the host immune system in disarray. In this paper, we present 2 case studies of secondary HLH driven by HM, followed by a review of the literature discussing the cytokines driving HLH, diagnostic criteria, and current treatments used or undergoing investigation.