A previously healthy 35-year-old male developed acute autoimmune hepatitis 5 weeks after receiving his second dose of an mRNA vaccine, presenting with jaundice, elevated liver enzymes, and abdominal pain. The condition rapidly progressed to severe hemophagocytic lymphohistiocytosis (HLH) and acute liver failure, confirmed by liver biopsy and bone marrow aspirate. Despite aggressive multidisciplinary treatment, including corticosteroids, immunoglobulin, and IL-1 antagonists, the patient deteriorated, developing multi-organ failure. Emergency liver transplantation was considered but was not viable due to his unstable condition. The case highlights a potential rare vaccine-associated immune response which we believe has not been reported in the literature, requiring prompt recognition and multidisciplinary management. Further research is needed to understand the underlying immunogenic triggers and optimize treatment.

Improved awareness of hemophagocytic lymphohistiocytosis (HLH) among clinicians has led to an increase in its diagnosis. Often diagnosis is made based on the HLH- 2004 criteria. While these criteria have considerable strengths, they lack specificity and may be fulfilled in the setting of many pro-inflammatory disorders. Genetic defects affecting cellular cytotoxicity cause familial (primary) HLH. On the other hand, secondary HLH is more a pathophysiologic process common to many conditions, rather than a singular disease entity. Improved genetic, immunologic, and functional testing have changed not only the way we diagnose HLH, but also how we treat it. In 2004, there were few active agents and regimens. In 2024, there are multiple safe and effective targeted therapies. We have begun to understand that routine and immediate use of etoposide-based therapy in secondary HLH is likely not appropriate, and emerging cytokine-directed therapies may be more rational interventions. Moreover, it is recognized that identifying and treating the driver of secondary HLH is at least as important as treating the cytokine storm and immune dysregulation. Unfortunately, over-reliance on, and narrow interpretation of, the HLH- 2004 criteria can lead to overdiagnosis, misdiagnosis, and unneeded exposure to drugs that can be harmful. It is important that clinicians understand the limitations of the current diagnostic paradigms for secondary HLH, and the shortcomings of reflexive use of etoposide-based therapy. Herein we will discuss the pros and cons of the current paradigm for the recognition, diagnosis, and treatment of secondary HLH.

Haemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder. Dengue fever is a common trigger for HLH in the tropics. We aimed to develop a simplified clinical tool to detect HLH in dengue patients.

A cross-sectional observational study was carried out at Kasturba Medical College Mangalore. Patients between 18 and 60 years of age, with dengue fever for more than five days with suspected HLH symptoms were selected. Hepatosplenomegaly, temperature, haemoglobin levels, total leucocyte count, platelet count, ferritin, triglyceride, and liver function tests were assessed. HLH-2004 criteria were used to confirm the diagnosis. A simple clinical tool was developed via decision tree analysis using clinical and laboratory parameters.

Patients with HLH had marked leucopenia, thrombocytopenia, hyperferritinaemia and elevated aspartate aminotransferase levels, and a greater incidence of hepatosplenomegaly than those without HLH. Decision tree analysis was used to generate a clinical diagnostic tool, which demonstrated an accuracy of 94%, at a confidence interval of 95% (90-98%). The model's ability to predict HLH was 79%, while its specificity was 96%. It had a positive predictive value of 68% and a negative predictive value of 97%. The kappa value of the predicted model was 0.70, indicating an agreement with the diagnosis using HLH-2004 criteria, with a significant p-value (< 0.001).

Splenomegaly can be used as a screening method to diagnose HLH in patients with dengue. By using an algorithmic approach, combining splenomegaly with leucopenia and thrombocytopenia, this clinical tool accurately detects HLH in patients with dengue.

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Pneumonia caused by Chlamydia abortus (C. abortus) is uncommon, particularly when complicated by severe acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS). Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal disease characterized by the uncontrolled activation and non-malignant expansion of macrophages and T lymphocytes. This report describes a case of severe pneumonia complicated by hemophagocytic lymphohistiocytosis, caused by Chlamydia abortus.

A 42-year-old female with no history of underlying medical conditions, no known exposure to poultry or avian animals, and no consumption of undercooked sheep or ewes contaminated with infected placenta, presented to the respiratory medicine department with a 3-day history of fever, cough, and sputum production. Initially diagnosed with community-acquired pneumonia, she was treated with piperacillin-tazobactam for 5 days. However, despite 12 h of high-flow oxygen therapy, her oxygenation did not improve, and she was transferred to the ICU, where she received additional treatments, including moxifloxacin and methylprednisolone. Her condition worsened further, prompting the initiation of veno-venous extracorporeal membrane oxygenation (VV-ECMO) and bronchoalveolar lavage for metagenomic next-generation sequencing (mNGS) analysis. The mNGS results identified Chlamydia abortus with a count of 180,791, leading to the cessation of moxifloxacin and the addition of omadacycline to her regimen. After 13 days of ECMO therapy, her condition improved, and the ECMO was discontinued. The endotracheal tube was successfully removed 15 days after intubation. However, 3 days later, the patient developed recurrent fever, pancytopenia, elevated ferritin, blood lipids, soluble CD25, and decreased natural killer cell activity, leading to a diagnosis of hemophagocytic lymphohistiocytosis (HLH). She was treated with ruxolitinib, etoposide, and other supportive medications. Despite treatment, her condition continued to deteriorate. Three days later, the family opted to discontinue therapy due to financial constraints. She passed away 12 h later.

Chlamydia abortus infection can result in severe acute respiratory distress syndrome (ARDS), necessitating prompt diagnosis and active clinical intervention. This case is unique due to the rare occurrence of HLH following Chlamydia abortus infection, a pathogen not commonly associated with this condition. Metagenomic next-generation sequencing (mNGS) offers a distinct advantage in rapidly and accurately identifying rare pathogen infections, while extracorporeal membrane oxygenation (ECMO) can be an effective treatment for severe pneumonia caused by Chlamydia abortus. It highlights the importance of early recognition and management of HLH in patients with severe, unexplained infections, particularly in those with unusual pathogens. Additionally, Chlamydia abortus infection may be complicated by HLH. Clinicians should remain vigilant for patients presenting with unexplained high fever, hepatosplenomegaly, and pancytopenia, and HLH screening should be initiated promptly. Early intervention can significantly improve patient survival rates.

IntroductionHaemophagocytic lymphohistiocytosis (HLH) is a rare and serious immunological syndrome that involves a strong activation of cytotoxic T lymphocytes and macrophages. HLH determines a cytokine-mediated tissue injury with a contemporary multi-organ failure and a high fatality rate.Material and methodsA retrospective study was performed considering the medical records of paediatric patients who underwent a bone marrow aspirate for suspect HLH. The biomarkers evaluated were among those included in the HLH-2004. Lactate dehydrogenase (LD) was also evaluated. Haemophagocytosis was evaluated in bone marrow blood smear slides.ResultsEnrolled were 11 patients included in the HLH group and 8 patients as controls. Haemoglobin and fibrinogen resulted lower in HLH patients than in controls, while blood triglycerides, serum ferritin and LD resulted increased. Blood triglycerides and fibrinogen discriminated HLH cases perfectly, with a sensitivity and specificity of 100%. Ferritin had a sensitivity of 100% and a specificity of 83% (cut off ≥3,721 µg/L) and LD of 73% and of 100% (the cut off ≥1,903 U/L). Haemoglobin was found to have a sensitivity of 75% and a specificity of 100% (cut off ≤ 96 g/L). Total haemophagocytes cell counts were not different between patients and controls. Only the increased number of phagocytized nucleated red blood cells (NRBC) was found to be significantly increased in the patients. Erythrocytes phagocytosis (≥4/1,000 cells) only tended towards significance.ConclusionsThe blood biomarkers showed better diagnostic performance than the morphological evaluation. Among the different cell lineages engulfed by haemophagocytes, the best diagnostic performance was obtained by phagocytosed mature erythrocytes and immature nucleated erythrocytes.

Dengue, a vector-borne acute febrile illness caused by members of the Flavivirus genus, has dramatically increased its occurrence worldwide. Neurological complications of dengue range from 2.63 to 40%, and subarachnoid hemorrhage is a rare, but significant manifestation. Hemophagocytic lymphohistiocytosis is a life-threatening hyperinflammatory syndrome, sometimes secondary to infections such as dengue. This report presents a rare case of severe dengue with subarachnoid hemorrhage and hemophagocytic lymphohistiocytosis. A 19-year-old male presented with a 7-day history of fever and myalgia, followed by severe headache and vomiting. Initial examination revealed high fever, hepatosplenomegaly, and pancytopenia. Lumbar puncture confirmed via computed tomography showed a Fisher Grade 2 subarachnoid hemorrhage with a small aneurysm at the junction of the left anterior coronary and anterior communicating arteries. Secondary hemophagocytic lymphohistiocytosis was diagnosed based on the criteria from 2004, with elevated inflammatory markers, hypertriglyceridemia, and hyperferritinemia. The patient was treated conservatively with intravenous fluids, osmotic diuretics, antiepileptics, steroids, and nimodipine. The patient showed clinical improvement and was discharged on the 11th day. Isolated subarachnoid hemorrhage is rare in dengue. The hyperinflammatory state in hemophagocytic lymphohistiocytosis, which is often overlooked due to nonspecific symptoms, can lead to aneurysm formation and rupture. Persistent fever, cytopenia, and hyperferritinemia should raise suspicion of hemophagocytic lymphohistiocytosis in cases of severe dengue with neurological complications. In patients with severe dengue and intracranial hemorrhage, clinicians should remain cautious for hemophagocytic lymphohistiocytosis to reduce the associated morbidity and mortality.

Patients with fever of unknown origin (FUO) can sometimes be accompanied by haemophagocytic lymphohistiocytosis (HLH), a life-threatening disease. The prognostic model and specific markers for the early prognosis and the optimized treatment regimen are of considerable research interest.

A total of 135 FUO/HLH patients were enrolled and classified according to the 60-day outcomes following diagnosis. 79 patients (including 5 patients lost in follow-up) enrolled from 2007 to 2015 served as the derivation cohort, and 56 patients from 2016 to 2023 served as the validation cohort. In the derivation cohort, 27 patients (27/74, 36.5%) survived within 60 days and multivariate analyses showed that age > 67 years (P = 0.003), baseline PLT < 42 × 10^9/L (P = 0.012) and LDH > 1505 U/L (P = 0.002) were associated with a higher mortality rate in HLH patients. The external validation proved the reliability of the prediction model. In derivation cohort, the median alteration of PLT (△PLT) were + 78 × 10^9/L and - 17 × 10^9/L in the survival and non-survival groups, respectively (P < 0.001). The median △LDH was - 197.5U/L in the survival group, while in the non-survival group was + 119U/L (P < 0.001).

Age, baseline LDH and PLT levels may predict early mortality in secondary HLH patients and identify patients in critical conditions. △LDH and △PLT levels were of high value to monitor the efficacy of therapeutic regimen and the disease progression in HLH patients.

Hemophagocytic lymphohistiocytosis (HLH) is a severe disease with a grim prognosis. This study aims to investigate the potential role of albumin to urea nitrogen ratio (AUR) as a predictor of 30-day mortality in adult HLH patients. This retrospective analysis involved patients admitted to the hospital with a first-time diagnosis of HLH between January 2015 and September 2021. The primary outcome was defined as 30-day all-cause mortality. Patients were categorized as survivors and non-survivors, as well as test and validation cohorts. Clinical signs and laboratory biomarkers on admission were picked up. A total of 467 patients were included in the study, with a 30-day mortality rate of 31.0% (n = 145). There were no significant differences observed between the test and validation cohorts. Surviving patients exhibited significantly higher levels of AUR. Multivariate analysis indicated that an AUR < 3.40 was deemed to be an independent risk factor (test cohort: HR: 3.663, P < 0.001; validation cohort: 2.475, P = 0.013; total cohort: 2.976, P < 0.001). The area under the receiver operating characteristic curve (AUC) values were 0.734 in the test cohort, 0.690 in the validation cohort, and 0.711 in the total cohort. AUR emerged as an independent and reliable risk indicator for 30-day mortality in adults with HLH, offering clinicians a tool to identify high-risk patients efficiently.

Hemophagocytic lymphohistiocytosis is a life-threatening cryptogenic inflammatory process. In some cases, the etiology is obscure, while in others multiple potential etiologies may be present. Diagnosis relies on observed findings rather than context.

GATA2 deficiency is an autosomal dominant disease that manifests with a range of clinical symptoms, including increased susceptibility to viral, bacterial, and fungal infections. Furthermore, the increased susceptibility to infections in GATA2 deficiency can trigger hemophagocytic lymphohistiocytosis (HLH) in these patients. Our systematic review evaluates reported cases of GATA2 deficiency and HLH in the literature.

A systematic review of case reports was conducted following PRISMA 2020 guidelines, encompassing studies retrieved from Ovid MEDLINE ALL, Embase via Ovid SP, Scopus, Web of Science, and Google Scholar from inception until June 14, 2024. This review included studies reporting patients diagnosed with GATA2 deficiency or having a documented history of the condition, who subsequently developed or were concurrently diagnosed with HLH. Various study types were considered, such as case reports, case series, letters to editors, original articles, correspondences, and commentaries, without any restrictions on language.

In our systematic review, 15 studies from 2016 to 2024 were analyzed, encompassing 23 patients with GATA2 deficiency and HLH. the mean (SD) age of patients was 23.48 (10.54) years, ranging from 7 to 57 years. These patients exhibited diverse genetic mutations and a spectrum of infections, particularly Mycobacterium avium (M. avium), Mycobacterium kansasii (M. kansasii), Epstein-Barr virus (EBV), cytomegalovirus (CMV), varicella-zoster virus (VZV), herpes simplex virus (HSV), and influenza A, often leading to HLH. Family histories of GATA2-deficient patients with HLH occasionally reveal confirmed GATA2 mutations or suspicious cases among first-degree relatives. Hematopoietic stem cell transplantation (HSCT) was performed in 8 patients with GATA2 deficiency and HLH. Among them, 6 patients survived post-therapy, while 2 patients died following HSCT. Currently, 1 patient is being considered for HSCT. The overall mortality rate among GATA2 deficiency patients who experienced HLH was 39.13%.

This systematic review highlights GATA2 deficiency's association with diverse infections triggering HLH, emphasizing early infection management to mitigate mortality risks. This comprehensive analysis contributes to scientific knowledge, offering important insights for clinicians and researchers in diagnosing and managing this rare condition.

There is a continuous cycle of activation and contraction in the immune response against pathogens and other threats to human health in life. This intrinsic yin-yang of the immune response ensures that inflammatory processes can be appropriately controlled once that threat has been resolved, preventing unnecessary tissue and organ damage. Various factors may contribute to a state of perpetual immune activation, leading to a failure to undergo immune contraction and development of cytokine storm syndromes. A literature review was performed to consider how the trajectory of the immune response in certain individuals leads to cytokine storm, hyperinflammation, and multiorgan damage seen in cytokine storm syndromes. The goal of this review is to evaluate how underlying factors contribute to cytokine storm syndromes, as well as the symptomatology, pathology, and long-term implications of these conditions. Although the recognition of cytokine storm syndromes allows for universal treatment with steroids, this therapy shows limitations for symptom resolution and survival. By identifying cytokine storm syndromes as a continuum of disease, this will allow for a thorough evaluation of disease pathogenesis, consideration of targeted therapies, and eventual restoration of the balance in the yin-yang immune response.

Immune checkpoint inhibitors (ICIs) constitute a pivotal class of immunotherapeutic drugs in cancer treatment. However, their widespread clinical application has led to a notable surge in immune-related adverse events (irAEs), significantly affecting the efficacy and survival rates of patients undergoing ICI therapy. While conventional hematological and imaging tests are adept at detecting organ-specific toxicities, distinguishing adverse reactions from those induced by viruses, bacteria, or immune diseases remains a formidable challenge. Consequently, there exists an urgent imperative for reliable biomarkers capable of accurately predicting or diagnosing irAEs. Thus, a thorough review of existing studies on irAEs biomarkers is indispensable. Our review commences by providing a succinct overview of major irAEs, followed by a comprehensive summary of irAEs biomarkers across various dimensions. Furthermore, we delve into innovative methodologies such as machine learning, single-cell RNA sequencing, multiomics analysis, and gut microbiota profiling to identify novel, robust biomarkers that can facilitate precise irAEs diagnosis or prediction. Lastly, this review furnishes a concise exposition of irAEs mechanisms to augment understanding of irAEs prediction, diagnosis, and treatment strategies.

The identification of haemophagocytosis in bone marrow (BM) is recurrently identified in patients with severe COVID-19. These initial COVID-19 autopsy studies have afforded valuable insight into the pathophysiology of this disease; however, only a limited number of case series have focused on lymphoid or haematopoietic tissues.

BM and lymph node (LN) specimens were obtained from adult autopsies performed between 1 April 2020 and 1 June 2020, for which the decedent had tested positive for SARS-CoV-2. Tissue sections (H&E, CD3, CD20, CD21, CD138, CD163, MUM1, kappa/lambda light chains in situ hybridisation) were examined by two haematopathologists, who recorded morphological features in a blinded fashion. Haemophagocytic lymphohistiocytosis (HLH) was assessed based on HLH 2004 criteria.

The BM demonstrated a haemophagocytic pattern in 9 out of 25 patients (36%). The HLH pattern was associated with longer hospitalisation, BM plasmacytosis, LN follicular hyperplasia and lower aspartate aminotransferase (AST), as well as ferritin at demise. LN examination showed increased plasmacytoid cells in 20 of 25 patients (80%). This pattern was associated with a low absolute monocyte count at diagnosis, lower white cell count and lower absolute neutrophil count at demise, and lower ferritin and AST at demise.

Autopsy results demonstrate distinct morphological patterns in BM, with or without haemophagocytic macrophages, and in LN, with or without increased plasmacytoid cells. Since only a minority of patients met diagnostic criteria for HLH, the observed BM haemophagocytic macrophages may be more indicative of an overall inflammatory state.

Hemophagocytic lymphohistiocytosis (HLH) during pregnancy is a rare and often misdiagnosed disease. The clinical manifestations are non-specific, contributing to a high maternal mortality rate. This case report details the presentation of a 31-year-old pregnant woman with high-grade fever initially treated as an infection-related condition. The diagnostic challenge arose from the rarity of HLH, its variable clinical presentation, and the lack of specificity in clinical and laboratory findings. Despite numerous tests and escalation of therapies, the patient, unfortunately, succumbed to HLH associated with T-cell lymphoma. This case report aims to raise awareness of HLH, emphasizing its challenging definition. Malignancy-associated HLH is not uncommon, and early identification and treatment are paramount to prevent progressive tissue damage, organ failure, and mortality. The atypical presentation of HLH as a clinical manifestation of T-cell lymphoma underscores the need for vigilance in diagnosing this potentially fatal syndrome.

This is a case of a 75-year-old male with a complicated past medical history who presented initially with weakness, fevers, exertional dyspnea, cough, and confusion. His initial workup revealed elevated aspartate transaminase (AST), alanine transaminase (ALT), bilirubin, and D-dimer. Right upper quadrant (RUQ) ultrasound revealed a partially contracted gallbladder with gallstones, so he underwent laparoscopic cholecystectomy. Due to worsening hyperbilirubinemia and anemia, he later underwent a liver biopsy which showed Epstein-Barr virus (EBV)-positive lymphoid infiltration. He developed anemia, thrombocytopenia, and low fibrinogen. He met the criteria for hemophagocytic lymphohistiocytosis (HLH) with 6/8 HLH-2004 criteria and an H score of 230 with a 96-98% probability of HLH. The patient was promptly treated with steroids, rituximab, and etoposide; however, the patient's health continued to deteriorate, and he expired. This case highlights the challenges of early diagnosis of HLH in the elderly patient population due to large differentials, confounding comorbidities, and the rarity of the diagnosis in this age range.

Effective post-transplant immunosuppression is essential to induce tolerance to allogeneic tissues and promote long-term graft survival. However, suppression of the immune system significantly increases the risk of opportunistic infections. In addition to the ongoing challenge of balancing graft survival and preventing infections, previous gold-standard calcineurin inhibitor-based immunosuppression also posed an increased risk of nephrotoxicity, cardiac disease, and diabetes. Belatacept is approved as an alternative to calcineurin inhibitor-based regimens. Although belatacept has improved cardiovascular and metabolic adverse events in renal transplant patients' but it carries a notably higher risk of long-term graft survival and renal toxicity, similar to calcineurin inhibitor-based regimens. However, there may be an increased risk of infections with its mechanism of action. We present a case of a 62-year-old female who developed disseminated histoplasmosis 18 months after being on belatacept-based immunosuppression after a deceased donor renal transplant for end-stage renal disease secondary to focal segmental glomerulosclerosis. Grocott Methenamine Stain (GMS) of peripheral blood smear showed intracellular yeast in neutrophils, consistent with histoplasmosis. Disseminated histoplasmosis was confirmed with positive bronchoalveolar lavage (BAL) and urine culture. The patient later developed hemophagocytic lymphohistiocytosis (HLH) secondary to immunosuppression and disseminated histoplasmosis. The patient succumbed to the disease despite maximal medical therapy. To our knowledge, there is one other published report of disseminated histoplasmosis in a patient with belatacept-based immunosuppression. The unique feature of this case is the development of HLH secondary to disseminated histoplasmosis while on belatacept. Further research is needed to evaluate the need for antifungal prophylaxis in patients on belatacept therapy.

Hemophagocytic lymphohistiocytosis (HLH) is considered a rare disease with high morbidity and mortality risks. Most research on this disease is conducted in pediatric settings. Therefore, this study aimed to describe the clinical characteristics, laboratory findings, and outcomes related to HLH in people living with human immunodeficiency virus (HIV)/AIDS) and disseminated histoplasmosis.

A retrospective and descriptive study was conducted in a tertiary hospital in México City from January 2018 to December 2022, including people living with HIV who had disseminated histoplasmosis confirmed through direct microbiological or immunological methods with an HScore ≥169 or who met 5 of the 8 HLH-2004 criteria.

HLH occurred in 36.1% (n = 26) of patients with HIV and disseminated histoplasmosis; the majority were men (84.9%), and their mean age (standard deviation) was 30.19 (5.6) years. The most frequent clinical manifestations were hepatomegaly (100%), fever (96.2%), and dyspnea (84.6%). The most common biochemical changes were hyperferritinemia (100%), elevated lactate dehydrogenase (100%), and bicytopenia (61.5%). Partial thromboplastin time (P = .012) and prothrombin time (P = .004) were associated with the 30-day mortality rate, and the 30-day survival rate was 65.4%.

We detected a high frequency of HLH; therefore, we encourage physicians to use diagnostic prediction tools (HLH-2004 and HScore criteria) in each reassessment for timely detection.

Dengue virus is an arbovirus transmitted through the bite of infected Aedes mosquitoes. Many unusual clinical features are being reported in dengue. Dengue complicated with hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially fatal condition. Here, we report an 18-year-old otherwise healthy female with dengue fever complicated with HLH. The diagnosis was made by fulfilling the clinical and laboratory criteria of HLH. She was managed successfully with a methylprednisolone pulse regimen. Our case highlights the importance of early recognition of complications and prompt treatment for a better outcome.

Ferritin is an established biomarker in the diagnosis of secondary hemophagocytic lymphohistiocytosis (HLH), which is diagnosed by the HLH-2004 criteria. Among these criteria, detection of hemophagocytosis through invasive procedures may delay early life saving treatment. Our aim was to investigate the value of hemophagocytosis in diagnosing HLH in critically ill patients.

In this secondary analysis of a retrospective observational study, we included all patients aged ≥18 years and admitted to any adult ICU at Charité-Universitätsmedizin Berlin between January 2006 and August 2018, who had hyperferritinemia (≥500 μg/L) and underwent bone marrow biopsy during their ICU course.

Two hundred fifty-two patients were included, of whom 31 (12.3%) showed hemophagocytosis. In multivariable logistic regression analysis, maximum ferritin was independently associated with hemophagocytosis. By removing hemophagocytosis from HLH-2004 criteria and HScore, prediction accuracy for HLH diagnosis was only marginally decreased compared to the original scores.

Our results strengthen the diagnostic value of ferritin and underline the importance of considering HLH diagnosis in patients with high ferritin but only four fulfilled HLH-2004 criteria, when hemophagocytosis was not assessed or not detectable. Proof of hemophagocytosis is not required for a reliable HLH diagnosis.

Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapy based on genetically engineered T cells derived from patients. The introduction of CAR T-cell therapy has changed the treatment paradigm of patients with B-cell lymphoid malignancies. However, challenging issues including managing life-threatening toxicities related to CAR T-cell infusion and resistance to CAR T-cell therapy, leading to progression or relapse, remain. This review summarizes the issues with currently approved CAR T-cell therapies for patients with relapsed or refractory B-cell lymphoid malignancies, including lymphoma and myeloma. We focus on unique toxicities after CAR T-cell therapy, such as cytokine-related events and hematological toxicities, and the mechanisms underlying post-CAR T-cell failure.

Visceral leishmaniasis (VL), often referred to as kala-azar, is quite rare in developed countries during pregnancy. Only few studies have evaluated its impact on perinatal outcome. It is caused primarily by Leishmania donovani or Leishmania infantum and presents with a wide spectrum of clinical manifestations from cutaneous ulcers to multisystem disease. Differential diagnosis is challenging as symptoms and signs are insidious, mimicking other diseases. Misdiagnosis can result in severe adverse perinatal outcomes, even maternal/neonatal death. Early treatment with liposomal amphotericin-B (LAmB) is currently the first choice with adequate effectiveness. We report a rare case of VL in a twin pregnancy with onset at the second trimester, presenting with periodic fever with rigors, right flank pain, and gradual dysregulation of all three cell lines. The positive rK39 enzyme-linked immunosorbent assay test confirmed the diagnosis. Treatment with LAmB resulted in clinical improvement within 48 h and in the delivery of two late-preterm healthy neonates with no symptoms or signs of vertical transmission. The one-year follow-up, of the mother and the neonates, was negative for recurrence. To our knowledge, this is the first reported case of VL in a twin pregnancy, and consequently treatment and perinatal outcome are of great importance.

Hemophagocytic lymphohistiocytosis (HLH) is a severe and frequently underdiagnosed disorder of systemic immune dysregulation resulting in hypercytokinemia and histologically evident hemophagocytosis, We report a case of a 34-year-old man who presented with breathlessness, generalized weakness, and fever of unknown origin with pancytopenia. Clinically the patient was admitted for febrile illness, and treated symptomatically but his general condition worsened leading to death within 21 hours of admission. A complete autopsy was performed. The deceased had a significant past history of repeated episodes of fever, weight loss, and axillary lymphadenopathy over a period of 8 months with multiple hospital admissions. He was also diagnosed with enteric fever (Widal test and Typhi IgM positive) at the start of these episodes. Hemogram during this period revealed persistent pancytopenia. Serum ferritin, serum triglycerides, and liver function tests were consistently deranged. Investigations for the etiology of fever and blood cultures were negative while the bone marrow aspirate revealed a normocellular marrow. CT abdomen-pelvis showed mild hepatomegaly with enlarged retroperitoneal lymph nodes. Infective endocarditis, lymphoma, and bronchopneumonia were being considered the clinical diagnoses. The significant autopsy findings were hepatosplenomegaly with retroperitoneal lymphadenopathy and multiple gastric ulcers. On microscopy, the liver, spleen, bone marrow, and lymph nodes showed characteristic hemophagocytosis. Post-mortem histopathological examination clinched the diagnosis of HLH and fulfilled six out of eight diagnostic criteria of the HLH-2004 protocol. We discuss the clinical course and diagnosis of this unique case and strive to create awareness about secondary HLH induced by common diseases, such as enteric fever.

Real-world data on the outcome of Asian patients with secondary hemophagocytic lymphohistiocytosis (HLH), especially on dengue-associated HLH, are limited to small case series. This is a retrospective records review of adult patients with secondary HLH between 2015 and 2020. Thirty-two adult patients were followed up for a median of 6.6 months (range 0.1 - 75 months). 15 had underlying lymphomas, and 12 had viral infections. Hemophagocytosis was seen in 28 of 29 patients with a bone marrow biopsy. 100% and 76.5% of patients with and without an underlying malignancy required HLH-directed therapy and blood product transfusion. 12 of 15 patients with lymphomas were treated with additional chemotherapy. Patients with malignancy-associated HLH had poorer survival than non-malignancy-associated HLH (median overall survival (OS) 1.5 months versus not reached, p-value 0.003). The 1-year survival rates of patients with malignancy-associated HLH, HLH with unknown etiologies, and infection-associated HLH were 0.133 (95% CI: 0.036 - 0.484), 0.400 (95% CI: 0.137 - 1.000) and 0.833 (95% CI: 0.647 - 1.000), respectively. Malignancy significantly increased the risk of death compared to infection-associated HLH (HR 9.37, p-value 0.003). Eight patients were diagnosed with dengue-associated HLH with a median HSCORE of 240 (98-99% probability of HLH). Their mean ferritin was 34,740 ng/mL. Three patients required blood product transfusion, 5 required corticosteroids and/or etoposide, with a median duration of treatment of 31 days. Their overall survival rate was 87.5%. Our study highlights the stark contrast in the survival of secondary HLH patients with and without an underlying malignancy. We also present one of the world's most extensive case series of dengue-associated HLH.

The laboratory diagnosis of cytokine storm syndromes (CSSs), i.e., hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS), is often challenging. The laboratory features using routinely available tests lack specificity, whereas confirmatory testing is available in only few laboratories in the United States. The disease mechanisms are still largely unclear, particularly in adults. In this chapter, the pathogenesis of CSSs, their associated laboratory findings, and recommended diagnostic strategies are reviewed.

Dengue fever is considered the most prolific vector-borne disease in the world, with its transmission rate increasing more than eight times in the last two decades. While most cases present mild to moderate symptoms, 5% of patients can develop severe disease. Although the mechanisms are yet not fully comprehended, immune-mediated activation leading to excessive cytokine expression is suggested as a cause of the two main findings in critical patients: increased vascular permeability that may shock and thrombocytopenia, and coagulopathy that can induce hemorrhage. The risk factors of severe disease include previous infection by a different serotype, specific genotypes associated with more efficient replication, certain genetic polymorphisms, and comorbidities such as diabetes, obesity, and cardiovascular disease. The World Health Organization recommends careful monitoring and prompt hospitalization of patients with warning signs or propensity for severe disease to reduce mortality. This review aims to update the diagnosis and management of patients with severe dengue in the intensive care unit.

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon condition, which can result either from a primary genetic abnormality affecting children or secondary to various conditions like malignancy or infection predominantly in adults. HLH is associated with immune dysregulation, resulting in an uncontrolled overproduction and infiltration of lymphocytes and histiocytes. The infiltration predominantly involves liver, spleen, lymph nodes, and central nervous system. Neuroimaging features on magnetic resonance imaging are highly nonspecific and variable. The most typical findings include periventricular white matter hyperintensities and diffuse atrophy. Ring or nodular enhancing or nonenhancing focal parenchymal lesions may be seen. Here, we present three pediatric cases of primary HLH with a wide spectrum of imaging findings involving cerebral and cerebellar cortex, white matter, deep gray matter, and brain stem. The findings in these patients range from small nonenhancing hemorrhagic lesions and enhancing small lesions to ill-defined mass with mass effect and midline shift. Lesions in deep gray matter including thalamus, basal ganglia, and also brain stem in HLH are rarely described in literature. Early diagnosis of HLH and timely management can improve the course of the disease.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome with a dismal prognosis. The underlying causes of HLH are diverse. However, the overabundance of cytokines was shared by all forms of HLH. Cytokine-targeted biotherapies have been increasingly used in HLH treatment.

In this review, we aim to provide an overview of biological treatment options for HLH.

Biological therapies offer alternative treatment options for patients with refractory/relapsed HLH or who are intolerant to conventional chemotherapies. As a complement to traditional treatment, biological agents improve response rates, maintain more protracted periods of remission, and reduce treatment related toxicity. A combination of biological agents may be a promising direction for HLH treatment. However, they may induce HLH to deteriorate and even trigger HLH.

Infection-associated hemophagocytosis is a diagnostic challenge. The varied presentation makes timely diagnosis difficult. We report two cases with unusual presentation of well-established secondary triggers for hemophagocytic lymphohistiocytosis.

Hemophagocytosis refers to the engulfment of hematopoietic cells by histiocytes. It can be seen in various conditions but is usually reported in the setting of hemophagocytic lymphohistiocytosis (HLH). Optimal interpretation of hemophagocytosis in the bone marrow in relation to the underlying disease significantly contributes to correct patient management.

The present study was done to identify the spectrum of conditions associated with hemophagocytosis in the bone marrow aspirates and grade the degree of hemophagocytosis.

This retrospective observational study included all the bone marrow aspirates showing hemophagocytosis, identified over a period of 5 years (January 2015 to January 2020). Two pathologists independently reviewed bone marrow slides. Hemophagocytosis was graded as mild, moderate, or severe by observing the number of histiocytes showing hemophagocytosis per 500 nucleated cells.

Eighty-eight patients showing hemophagocytosis in the bone marrow aspirate smear were included in the study. The most common cause of hemophagocytosis was infection (18%). There were 4 (5%) cases of HLH. Grade 1 (mild) hemophagocytosis was seen in 25 (29%) cases followed by Grade 2 (moderate) in 53 (60%) cases and Grade 3 (severe) in 10 (11%) cases. Fever was the most common clinical symptom present in 45 (51%) cases.

Hemophagocytosis in bone marrow aspirates is a common and under-reported finding. It is not only seen in cases of HLH but also in infections and other conditions. Documenting hemophagocytosis, even in the absence of fulfilled HLH criteria, is vital to explain cytopenias.

Haemophagocytic lymphohistiocytosis (HLH) is an uncommon systemic inflammatory syndrome that can happen secondary to numerous conditions. It rarely occurs due to dengue infection causing significant mortality and morbidity even with appropriate treatment. The outcome is further poor if the diagnosis of HLH is delayed or left untreated. Therefore, a high degree of clinical suspicion is paramount in diagnosing HLH.

A 17-year-old Sinhalese boy was admitted to a tertiary care hospital in Sri Lanka with a 4-day history of fever, headache, nausea, vomiting, and diarrhea. He was hemodynamically stable, and the serological investigation confirmed a dengue infection. On the fifth day of fever, he entered the critical phase of dengue infection, confirmed by ultrasound evidence of plasma leaking. However, he had ongoing high fever spikes during the critical phase, and even after the critical phase was over, the fever spikes continued. Simultaneously, hepatosplenomegaly was noticed, and he showed persistent thrombocytopenia, neutropenia, and anemia despite the resolution of the critical phase. Further, the workup revealed a serum ferritin level of > 3000 ng/mL triglyceride level of 314 mg/dL, and the bone marrow biopsy revealed an increased haemophagocytic activity. Secondary HLH was diagnosed on the basis of criteria used in the HLH-2004 trial and successfully managed with intravenous dexamethasone 10 mg/body surface area/day for the first 2 weeks, followed by a tapering regimen over 8 weeks.

This case emphasizes the need to consider HLH as a potential complication when persistent fever and cytopenias are present after recovering from dengue fever, particularly in patients with unusual clinical features like hepatosplenomegaly. Early recognition and prompt treatment with appropriate immunosuppressive therapy, such as intravenous dexamethasone, can lead to a successful response and good prognosis.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has affected all countries worldwide. Although some symptoms are relatively mild, others are still associated with severe and even fatal clinical outcomes. Innate and adaptive immunity are important for the control of SARS-CoV-2 infections, whereas a comprehensive characterization of the innate and adaptive immune response to COVID-19 is still lacking and the mechanisms underlying immune pathogenesis and host predisposing factors are still a matter of scientific debate. Here, the specific functions and kinetics of innate and adaptive immunity involved in SARS-CoV-2 recognition and resultant pathogenesis are discussed, as well as their immune memory for vaccinations, viral-mediated immune evasion, and the current and future immunotherapeutic agents. We also highlight host factors that contribute to infection, which may deepen the understanding of viral pathogenesis and help identify targeted therapies that attenuate severe disease and infection.

Tuberculosis (TB) is a disease of global concern due to its varying clinical presentations and outcomes. Hemophagocytic lymphohistiocytosis (HLH) syndrome, along with obstructive jaundice, is one of the rarest presentations of tuberculosis involving immune activation and has a very high mortality rate. Thus, on-time diagnosis becomes crucial for the management of the disease. Prompt treatment with anti-tubercular therapy (ATT) can limit the morbidity and mortality associated with it. We report the case of a 28-year-old male who presented with fever, yellowish discoloration of the skin, features of bicytopenia, jaundice with hepatosplenomegaly, and ascites. The liver function test (LFT) was suggestive of obstructive jaundice. TB was confirmed on the analysis of lymph node aspirates, and the contrast-enhanced computed tomography (CECT) of the thorax and abdomen was suggestive of disseminated tuberculosis. Upon investigation, the criteria for HLH were fulfilled. Bone marrow aspiration smears revealed multiple hemophagocytic histiocytes in the background of a hypercellular marrow, erythroid hyperplasia, and myeloid-to-erythroid ratio of 1:1. Thus, a diagnosis of disseminated TB with HLH and obstructive jaundice was established. A modified ATT regimen was started, keeping in mind the deranged LFT of the patient, but no immunosuppressive therapy was initiated as it could make the TB worse. This case demonstrates the fact that in cases of hemophagocytic syndrome with tuberculosis as an underlying cause, just starting ATT without immunosuppression could be rewarding and lifesaving.

Cases of anaplasmosis have increased steadily and are appearing in states where it is less common. While symptoms are usually mild, in rare cases it can cause hemophagocytic lymphohistiocytosis. Here, we present a case of polymerase chain reaction-confirmed Anaplasma phagocytophilum with morulae on peripheral blood smear associated with biopsy-proven hemophagocytic lymphohistiocytosis.

Secondary hemophagocytic syndrome (HPS) and systemic inflammatory response syndrome (SIRS) share similar clinical findings as a result of hyperinflammation. Due to high mortality rates in HPS; it is critical to diagnose promptly. Thus, this study aimed to evaluate the diagnostic and prognostic significance of inflammatory markers in these two increased inflammatory states.

We conducted a prospective observational study including patients hospitalized in the intensive care unit of the Internal Medicine Department of Ege University Hospital.

Thirty-three patients with HPS and 46 patients with SIRS were evaluated. Serum ferritin and sIL-2r levels were significantly higher in the HPS group than in the SIRS group, as expected. Receiver operating curve (ROC) analysis showed that the optimal cutoff for ferritin to distinguish HPS from SIRS was 1703 μg/L (sensitivity: 75%, specificity: 94.1%, area under the curve (AUC): 0.871, p < 0.001), and that for sIL-2r was 5888 U/ml (sensitivity: 45.5%, specificity: 89.1%, AUC: 0.698, and p = 0.001). Temporal changes (Δ) in ferritin were determined as a mortality predictor. When evaluated in terms of prognostic significance in ROC analysis, a decrease in ferritin of less than 38% was the cutoff value (sensitivity: 92.3%, specificity: 76.9%, AUC: 0.888, and p < 0.001), in mortality. Contrarily, neither baseline nor temporal change in sIL-2r did not achieve prognostic significance as a mortality predictor.

In this single-center study, serum ferritin level was found to be a particularly more valuable diagnostic and prognostic marker than sIL-2r in patients with HPS.

Hemophagocytic lymphohistiocytosis (HLH), a hyperinflammatory hyperferritinemic syndrome, is triggered by various etiologies and diseases and can lead to multiorgan dysfunction and death. There are two types of HLH: primary and secondary. Primary HLH (pHLH) is caused by a genetic mutation resulting in dysfunction in cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, hyperactivated immune cells, and hypercytokinemia. In secondary HLH (sHLH), an underlying etiology is the cause of the disease. Infections, malignancy, and autoimmune diseases are well-known triggers for sHLH. Infectious triggers for sHLH are most frequently viruses, where different mechanisms, including dysregulated CTLs and NK cell activity and persistent immune system stimulation, have been reported. Similarly, in severe coronavirus disease 2019 (COVID-19) patients, a hyperinflammatory mechanism leading to hypercytokinemia and hyperferritinemia has been demonstrated. A similar dysfunction in CTLs and NK cells, persistent immune system stimulation with increased cytokines production, and severe end-organ damage have been reported. Therefore, a significant overlap is present between the clinical and laboratory features seen in COVID-19 and sHLH. However, SARS-CoV-2, similar to other viruses, can trigger sHLH. Hence, a diagnostic approach is needed in severe COVID-19 patients presenting with multiorgan failure, in whom sHLH should be considered.

The hyperinflammatory immune response in severe COVID-19 infection shares features with secondary hemophagocytic lymphohistiocytosis (sHLH) in the form of fever, cytopenia, elevated inflammatory markers, and high mortality. There are contrasting opinions regarding utility of HLH 2004 or HScore in the diagnosis of severe COVID-19-related hyperinflammatory syndrome (COVID-HIS). This was a retrospective study of 47 patients of severe COVID-19 infection, suspected to have COVID-HIS and 22 patients of sHLH to other illnesses, to evaluate the diagnostic utility and limitations of HLH 2004 and/or HScore in context to COVID-HIS and to also evaluate the utility of Temple criteria for predicting severity and outcome in COVID-HIS. Clinical findings, hematological, and biochemical parameters along with the predictor of mortality were compared between two groups. Only 6.4% (3/47) of cases fulfilled ≥5/8 HLH 2004 criteria and only 40.52% (19/47) of patients showed HScore >169 in COVID-HIS group. 65.9% (31/47) satisfied the Temple criteria in COVID-HIS as compared with 40.9% (9/22) in the non-COVID group (p = 0.04). Serum ferritin (p = 0.02), lactate dehydrogenase (p = 0.02), direct bilirubin (p = 0.02), and C-reactive protein (p = 0.03) were associated with mortality in COVID-HIS. Both HScore and HLH-2004 criteria perform poorly for identifying COVID-HIS. Presence of bone marrow hemophagocytosis may help to identify about one-third of COVID-HIS missed by the Temple Criteria.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition characterized by uncontrolled activation of the immune system. HLH is a reactive mononuclear phagocytic response that occurs in association with a constellation of conditions such as malignancies and infections. The clinical diagnosis of HLH remains challenging because HLH can present with symptoms that significantly overlap with other causes of cytopenia, such as sepsis, autoimmune diseases, hematological cancers, and multiorgan failure. A 50-year-old man went to the emergency room (ER) for hyperchromic urine, melena, gingivorrhagia, and spontaneous abdominal wall hematomas. The first blood tests showed severe thrombocytopenia, alteration of the INR, and consumption of fibrinogen, and therefore, a diagnosis of disseminated intravascular coagulation (DIC) was made. A bone marrow aspirate showed numerous images of hemophagocytosis. With the suspicion of immune-mediated cytopenia, oral etoposide, intravenous immunoglobulin, and intravenous methylprednisolone were administered. Then, a diagnosis of gastric carcinoma was performed with a lymph node biopsy and gastroscopy. On the 30th day, the patient was transferred to the oncology ward of another hospital. On admission, he had serious piastrinopenia, anemia, hypertriglyceridemia, and hyperferritinemia. He was supported with a platelet transfusion and underwent a bone biopsy that showed a picture compatible with myelophthisis from diffuse medullary localization of a carcinoma of gastric origin. A diagnosis of HLH secondary to solid neoplasm was formulated. The patient started chemotherapy with oxaliplatin, calcium levofolinate, 5-fluorouracil bolus, 5-fluorouracil for 48 h (mFOLFOX6), and methylprednisolone. Six days after the third cycle of mFOLFOX6, the patient was discharged with the stabilization of his piastrinopenia condition. The patient continued chemotherapy with an improvement in his clinical conditions and normalization of hematological values. After 12 cycles of mFOLFOX, it was decided to start maintenance chemotherapy with capecitabine but, unfortunately, after only one cycle, HLH reappeared. The oncologist has to keep in mind the existence of HLH when there is an unusual clinical presentation of cancer, such as cytopenia affecting ≥2 lineages and alterations of ferritin and triglycerides other than fibrinogen and coagulation. Increased attention and additional research as well as a close collaboration with hematologists are needed to benefit patients with solid tumors complicated by HLH.

Subcutaneous panniculitis-like T cell lymphoma (SPTCL) is a rare cutaneous T cell lymphoma, which is indolent in nature but could claim life if not correctly diagnosed and promptly treated. SPTCL is usually presented clinically as painless subcutaneous and erythematous nodules over the trunk or extremities. Active clinical vigilance for these subcutaneous nodules or panniculitis-like lesions is warranted. A biopsy must be performed in order to make a correct diagnosis. Positron emission tomography scan is utilized for disease staging and treatment follow-up. Due to the rarity of this lymphoma, a standard treatment protocol is not established yet. However, most cases of SPTCL could be treated well under immunosuppressive or polychemotherapeutic drugs except in cases with hemophagocytic syndrome. Hematopoietic stem cell transplantation may be used in refractory or relapse cases. In this review, we presented a case of SPTCL with long-term complete remission. Meanwhile, since most clinical evidences and experiences of SPTCL are based mostly on case reports or small case series, and the understanding of the SPTCL pathophysiology is limited, we reviewed and updated the pathophysiology and treatments of SPTCL.

As Twitter has gained significant popularity, tweets can serve as large pool of readily available data to estimate the adverse events (AEs) of medications.

This study evaluated whether tweets were an early indicator for potential safety warnings. Additionally, the trend of AEs posted on Twitter was compared with AEs from the Yellow Card system in the United Kingdom.

English Tweets for 35 drug-event pairs for the period 2017-2019, two years prior to the date of EMA Pharmacovigilance Risk Assessment Committee (PRAC) meeting, were collected. Both signal and non-signal AEs were manually identified and encoded using the MedDRA dictionary. AEs from Yellow Card were also gathered for the same period. Descriptive and inferential statistical analysis was conducted using Fisher's exact test to assess the distribution and proportion of AEs from the two data sources.

Of the total 61,661 English tweets, 1,411 had negative or neutral sentiment and mention of at least one AE. Tweets for 15 out of the 35 drugs (42.9%) contained AEs associated with the signals. On pooling data from Twitter and Yellow Card, 24 out of 35 drug-event pairs (68.6%) were identified prior to the respective PRAC meetings. Both data sources showed similar distribution of AEs based on seriousness, however, the distribution based on labelling was divergent.

Twitter cannot be used in isolation for signal detection in current pharmacovigilance (PV) systems. However, it can be used in combination with traditional PV systems for early signal detection, as it can provide a holistic drug safety profile.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been associated with multiple inflammatory symptoms involving several organ systems, including hematologic manifestations. Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome caused by excessive inflammation in the absence of immune regulation. We present the case of a patient with HLH secondary to dysregulated inflammatory response following COVID-19; we also describe the diagnostic and management challenges associated with the condition.

We aimed to describe Familial Hemophagocytic Lymphohistiocytosis (F-HLH) patients' clinical features, intensive care courses, and outcomes.

Multi-center retrospective cohort study of pediatric patients diagnosed with F-HLH from 2015 to 2020 in five tertiary centers in Saudi Arabia. Patients were classified as F-HLH based on their genetic confirmation of known mutation or on their clinical criteria, which include a constellation of abnormalities, early disease onset, recurrent HLH in the absence of other causes, or a family history of HLH.

Fifty-eight patients (28 male, 30 female), with a mean age of 21.0 ± 33.9 months, were included. The most common principal diagnosis was hematological or immune dysfunction (39.7%), followed by cardiovascular dysfunction in 13 (22.4%) patients. Fever was the most common clinical presentation in 27.6%, followed by convulsions (13.8%) and bleeding (13.8%). There were 20 patients (34.5%) who had splenomegaly, and more than 70% of patients had hyperferritinemia >500 mg/dl, hypertriglyceridemia >150 mg/dl and hemophagocytosis in bone marrow biopsy. Compared to deceased patients 18 (31%), survivors had significantly lower PT (p = 041), bilirubin level of <34.2 mmol/L (p = 0.042), higher serum triglyceride level (p = 0.036), and lesser bleeding within the initial 6 h of admission (p = 0.004). Risk factors for mortality included requirements of higher levels of hemodynamic (61.1% vs. 17.5%, p = 0.001) and respiratory (88.9% vs. 37.5%, p < 0.001) support, and positive fungal cultures (p = 0.046).

Familial HLH still represents a challenge in the pediatric critical care setting. Earlier diagnosis and prompt initiation of appropriate treatment could improve F-HLH survival.

This review article describes the pathophysiology of hemophagocytic lymphohistiocytosis (HLH). The condition is characterized by excessive stimulation of inflammatory cytokines, lymphocytes, and macrophages, leading to hyperinflammatory disorder with immune dysfunction. The main clinical and diagnostic features include fever ≥38.5°C, splenomegaly, hyperferritinemia, cytopenia, hypofibrinogenemia, hemophagocytosis on the bone marrow, low or absent of natural killer (NK) cell activity, and elevated soluble CD25. Various immunological and inflammatory mechanisms are involved in the pathogenesis of HLH. Moreover, the condition can result in multisystem organ failure, contributing to the high mortality rate in hospital settings. A thorough literature search was conducted by collecting data from multiple articles published on PubMed, Medline, and Google Scholar. The article discusses the cellular and molecular pathways that lead to HLH. Due to the high rate of morbidity and mortality, early diagnosis needs to be established. More research pertaining to molecular biology, immunology, and the genetics of HLH is needed to explore the effective management and treatment of this rare disorder.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of immune dysregulation primarily driven by the cytokine interferon gamma. It can be either a genetic or acquired disorder associated with infection, malignancy, and rheumatologic disorders. Trisomy 21 can express a wide range of phenotypes which include immune dysregulation and shares inherent pathophysiology with a group of disorders termed interferonopathies. Knowledge of this overlap in seemingly unrelated conditions could provide a basis for future research, and most importantly, alternative therapeutic interventions in acute life threatening clinical scenarios. Herein, we describe two patients with trisomy 21 presenting with HLH that was refractory to conventional treatment. Both patients were successfully managed with novel interventions targeting the interferon pathway.

We describe a 17-month-old male and 15-month-old female with trisomy 21 presenting with a myriad of signs and symptoms including fever, rash, cytopenias, and hyperferritinemia, both ultimately diagnosed with HLH. Each had relapsing, refractory HLH over time requiring several admissions to the hospital receiving conventional high dose corticosteroids and interleukin-1 inhibition therapy. Successful steroid-free remission was achieved after targeting interferon inhibition with emapalumab induction followed by long-term maintenance on baricitinib.

To our knowledge, these are the first reported cases of relapsed, refractory HLH in patients with trisomy 21 successfully treated with emapalumab and transitioned to a steroid-sparing regimen with oral baricitinib for maintenance therapy. Trisomy 21 autoimmunity and HLH are both thought to be driven by interferon gamma. Targeting therapy toward interferon signaling in both HLH and autoimmunity in trisomy 21 may have potential therapeutic benefits. Further investigation is needed to determine if trisomy 21 may predispose to the development of HLH given this common pathway.