Hemophagocytic Lymphohistiocytosis

FDG-PET/CT Findings in Hemophagocytic Lymphohistiocytosis

A 44-year-old man was admitted to the hospital with fever, pancytopenia, and a new rash. FDG-PET was ordered in light of nonspecific clinical, imaging, and biopsy findings. Findings included diffuse FDG uptake throughout the subcutaneous fat overlying fat stranding/haziness on CT. FDG uptake was associated with scattered subsolid/ground-glass lesions in the lungs. Splenomegaly and increased FDG uptake throughout the bone marrow were seen. Diagnostic considerations included infectious versus lymphomatous processes, and possible sites for biopsy were identified. Biopsy of a highly FDG-avid lung lesion led to a diagnosis of hemophagocytic lymphohistiocytosis secondary to peripheral T-cell lymphoma, not otherwise specified.

Simultaneous intravascular large B‑cell lymphoma and papillary thyroid carcinoma: A case report

Intravascular large B-cell lymphoma (IVLBCL) is a rare subtype of B-cell lymphoma. The concurrence of IVLBCL and papillary thyroid carcinoma (PTC) is extremely rare. A 63-year-old woman was diagnosed with double-expression IVLBCL that presented as a hemophagocytic syndrome, complicated by PTC. IVLBCL was diagnosed by positron emission tomography/computed tomography (PET/CT) before bone marrow biopsy. Immunofixation electrophoresis displayed M proteins positive and IgG kappa light chains that the differential diagnosis should have included both multiple myeloma and IVLBCL. After treatment with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, prednisone and etoposide, the patient's cytokine titres and other laboratory indicators returned to normal. PET/CT showed that complete remission had been achieved. She has been taking zanubrutinib for 1.5 years and remains in remission. This is a report of a patient with hemophagocytic syndrome-associated IVLBCL with CCND1 and DNMT3A gene mutations combined with PTC and describes changes before and after treatment.

Deep insight into cytokine storm: from pathogenesis to treatment

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.

Haemophagocytic lymphohistiocytosis (HLH) with concurrent Hodgkin's Disease

Haemophagocytic lymphohistiocytosis (HLH) is a condition of uncontrolled immune activation caused by genetic defects or triggered by infections, malignancies, autoimmune diseases, drugs, pregnancy or post-transplant immunosuppression. This case describes a young man presenting with clinical jaundice and abnormal blood tests, including raised inflammatory markers, abnormal liver function, low haemoglobin (65 g/L) and a low white blood cell count (3.08×109/L). He met five out of eight HLH criteria and tested positive for Epstein-Barr virus (EBV) PCR (58 011 IU/mL). His bone marrow biopsy showed EBV-driven Hodgkin's lymphoma. He was initially treated with the HLH-94 protocol and later switched to ABVD chemotherapy (adriamycin, bleomycin, vinblastine and dacarbazine). He steadily recovered despite a prolonged hospital stay. He was discharged to complete his remaining cycles of chemotherapy as an outpatient with a plan of having a positron emission tomography (PET) scan after two cycles of chemotherapy.

Modified G-CSF/ATG-Based Haploidentical Transplantation Protocol in Pediatric Primary Hemophagocytic Lymphohistiocytosis: A Long-Term Follow-Up Single-Center Experience

BACKGROUND

Primary hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome caused by immune dysregulation. Hematopoietic stem cell transplantation (HSCT) represents the only option for long-term cure for primary HLH. However, only around 25% of patients have a fully HLA-matched donor.

METHODS

In this retrospective study, we analyzed 42 pediatric patients with primary HLH who underwent haplo-SCT using the modified granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG)-based protocol. The conditioning regimen included 300-600 mg/m2 etoposide (VP16), along with low doses of busulfan (Bu) (0.8-1.2 mg/kg every 6 hours on Days -8 to -6), cyclophosphamide (Cy) (10 mg/kg/day on Days -4 to -3), fludarabine (Flu) (30 mg/m2/day on Days -5 to -3), and ATG (8-9 mg/kg total dose on Days -5 to -2) to reduce complications.

RESULTS

All 42 patients achieved successful engraftment. Following a median follow-up period of 48.7 months, 32 of the 42 patients remained alive and disease free. The 2-year overall survival (OS) rate was 78.4%, and the 5-year OS rate was 73.7%. The 2-year failure-free survival (FFS) rate was 71.3%, and the 5-year FFS rate was 66.5%. Patients who achieved complete remission at the time of HSCT showed better OS (p < 0.05). The incidence of Grade III-IV acute graft-versus-host disease (GVHD) was 26.2%, and severe chronic GVHD was observed in 11.9% of patients. Thrombotic microangiopathy occurred in 13 patients, and veno-occlusive disease in two patients.

CONCLUSIONS

This modified G-CSF/ATG-based haploidentical protocol demonstrates significant potential for pediatric patients with primary HLH, exhibiting commendable effectiveness and safety.

Predicting 30-day mortality in hemophagocytic lymphohistiocytosis: clinical features, biochemical parameters, and machine learning insights

This study aims to evaluate the clinical characteristics and biochemical parameters of hemophagocytic lymphohistiocytosis (HLH) patients to predict 30-day mortality. Parameters analyzed include lymphocyte count (L), platelet count (PLT), total protein (TP), albumin (ALB), blood urea nitrogen (BUN), and activated partial thromboplastin time (APTT). Machine learning (ML) approaches, including LASSO, random forest (RF), and support vector machine (SVM), were employed alongside meta-analysis and sensitivity analysis to validate the prognostic potential of these indicators. A retrospective analysis of 151 HLH patients was conducted to identify key predictive variables. Receiver operating characteristic (ROC) analysis, Kaplan-Meier (K-M) survival curves, and Cox regression analysis were used to evaluate the predictive capabilities of these parameters. ML algorithms determined optimal cut-off values to classify patients into high-risk and low-risk groups. A survival nomogram and risk scoring system were developed to provide individualized prognostic assessments. Meta-analysis aggregated data from existing literature to further validate differences in PLT, ALB, and APTT between deceased and surviving patients. Older age, low L, low PLT, low ALB, elevated BUN, and prolonged APTT were strongly associated with higher 30-day mortality risk in HLH patients. Six key indicators-TP, L, APTT, BUN, ALB, and PLT-were identified as critical predictors. ROC and K-M survival analyses highlighted the significance of these parameters. The survival nomogram and risk scoring system demonstrated high accuracy in predicting individualized mortality risk. Meta-analysis confirmed significant differences in PLT, ALB, and APTT between deceased and surviving patients, reinforcing the clinical value of these indicators. This study underscores the prognostic importance of specific clinical and biochemical parameters in predicting 30-day mortality in HLH patients. By integrating ML methodologies, a survival nomogram and risk scoring system were developed, offering valuable tools for early diagnosis, prognosis assessment, and personalized treatment planning in clinical practice.

Langerhans Cell Histiocytosis and Other Histiocytic Lesions

BACKGROUND

Histiocytoses, including Langerhans cell histiocytosis (LCH), comprise a diverse group of histiocytic disorders characterized by the abnormal accumulation and proliferation of histiocytes in various tissues or organs throughout the body, ranging from benign, self-limited conditions to aggressive malignancies and systemic inflammatory syndromes. These lesions present unique diagnostic challenges due to their broad spectrum of clinical presentations, overlapping histopathological and immunophenotypical features, and genetic complexity.

METHODS

This review analyzes major histiocytic lesions, focusing on their epidemiology, clinical presentations, histologic and immunophenotypic features, and genetic characteristics to facilitate accurate diagnosis and differentiation among these histiocytoses.

RESULTS

LCH, a well-recognized lesion, can affect various organ systems and necessitates differentiation from other types of histiocytoses such as Erdheim-Chester disease (ECD), Rosai-Dorfman-Destombes disease (RDD), and cutaneous and mucocutaneous non-Langerhans cell histiocytoses. Some histiocytic lesions, such as histiocytic sarcoma, are inherently malignant, while others, like hemophagocytic lymphohistiocytosis (HLH), manifest as severe, potentially life-threatening systemic inflammatory syndromes. Recent molecular genetic studies revealed recurrent genetic alterations in the MAPK pathway, such as BRAF V600E and MAP2K1 in LCH and ECD, and KRAS, NRAS, and MAP2K1 mutations in a subset of RDD. Malignant histiocytoses frequently show alterations in tumor suppressor genes like TP53 and CDKN2A.

CONCLUSION

Precise classification of histiocytic lesions relies on a comprehensive diagnostic approach that integrates clinical, histologic, immunophenotypic, and genetic data. Recent genetic advances shed light on these conditions' unique but occasionally overlapping pathogenic mechanisms. Molecular genetics advancements continue to refine diagnostic accuracy and present new therapeutic targets, especially for aggressive or treatment-resistant cases.

Molecular Mutations in Histiocytosis: A Comprehensive Survey of Genetic Alterations

Histiocytosis represents a group of uncommon disorders characterized by the abnormal accumulation of specialized immune cells, such as macrophages, dendritic cells, or monocyte-derived cells, in various tissues and organs. Over 100 distinct subtypes have been documented, each displaying a broad spectrum of clinical presentations and histological characteristics. Till today, histiocytosis has been addressed through a combination of chemotherapy, radiotherapy, and surgery, with varying responses from individual patients. Due to its atypical symptoms, it has been prone to misdiagnosis. Advances in our understanding of the cellular and molecular aspects of these conditions are paving the way for improved diagnostic methods and targeted therapies. Researchers have extensively investigated various mutations in patient samples. However, no paper has yet provided a comprehensive summary of the collective analysis of mutations and pathways. Hence, this paper consolidates research efforts that specifically concentrate on gene mutations identified in patient samples of different subtypes of histiocytosis. These insights are essential for developing targeted therapies and improving diagnosis. Further, it provides potential insights to enhance the development of more effective therapeutic approaches for rare diseases.

Critical risk factors analysis of infection-associated hemophagocytic lymphohistiocytosis in children

To analyze the critical factors of infection-associated Hemophagocytic lymphohistiocytosis (HLH) in children, so as to provide theoretical basis for clinicians to evaluate the disease condition, formulate treatment plan and improve prognosis. This study is a retrospective analysis. 60 cases of children with infection-associated HLH were divided into critical and non-critical groups based on the presence of multiple organ dysfunction syndrome (MODS), and the clinical characteristics and laboratory data of the two groups of children were analyzed. A multifactor logistic regression analysis model was used to assess the independent risk factors affecting critical illness in children with infection-associated HLH, and the Receiver Operating Characteristic (ROC) curve analysis was used to evaluate the predictive value of risk factors for critical illness in children with infection-associated HLH. Children in the critical group with HLH had a younger age at onset. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), D-dimer (DD), and triglycerides (TG) were significantly higher in the critical group, while albumin (ALB) was significantly lower, showing statistical significance (P < 0.05). Multifactorial logistic regression analysis of age, ALB, and TG showed that younger age and lower ALB were associated with a higher risk of MODS in children with infection-associated HLH, with age and ALB being independent risk factors for critical illness. ALB predicted the ROC area under the curve for critical children with infection-associated HLH was 0.765 (95% CI: 0.643-0.888, P = 0.011), with the optimal cut-off value being 32.50 g/L (sensitivity = 68.3%, specificity = 84.2%); age predicted the ROC area under the curve for critical children with infection-associated HLH was 0.711 (95% CI: 0.570-0.851, P = 0.009), with the optimal cut-off value being 1.50 years (sensitivity = 70.7%, specificity = 68.4%). This study suggests that younger patients and those with hypoalbuminemia among infection-related HLH patients are more likely to develop MODS. In the future, verification will be required through large-scale, multi-center studies.

Clinical spectrum of primary hemophagocytic lymphohistiocytosis: experience of reference centers in Central and Southeast Anatolia

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, with a high mortality if left untreated. In addition, the disease has unique diagnostic challenges. Therefore, despite the existing guidelines on management, current clinical practice data is informative on the course and outcome. Herein, a retrospective chart review study was conducted through the collaboration of six centers, located in central and southeastern Türkiye. The demographical data, laboratory results, and treatment outcomes were evaluated. Eighty-three patients were enrolled in the study. The mean age was 2 years, whereas the median age was 8 months with a range of a minimum of 1 week and a maximum of 12.6 years. Consanguineous marriage, history of sibling death, and familial history of similar disease were determined in 72.2% (n:60), 34.9% (n:29), and 39.8% (n:33) of the patients, respectively. The most common presentation was fever, followed by hepatosplenomegaly on admission. Disease-causing familial HLH variants were identified in 60.2% (n:50) of the patients. Hematopoietic stem cell transplantation (HSCT) was performed in 39.7% (n:33) of the cohort. The 2-year overall survival (OS) rate was 62.4% for the whole group. Comparing the patients who received HSCT and those who did not; the HSCT group had a 2-year OS of 84.7%, which was significantly better than patients who did not receive HSCT had a 2-year OS of 47.1% (p:0.001). Despite the improvement in HLH diagnostics and treatment options over the last decade, early death remains a leading problem for the survival of these patients. Therefore, appropriate assessment of the patients in experienced centers and HSCT are pivotal for better outcomes.

Development of Preliminary Criteria of Macrophage Activation Syndrome in Multisystem Inflammatory Syndrome Associated with COVID-19 in Children

Background: Macrophage activation syndrome (MAS) can be regarded as a key factor determining the severity of multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C), and often requires treatment in the intensive care unit (ICU) to avoid life-threatening complications. No reputable specific criteria for the diagnosis of MAS in MIS-C patients have yet been identified, and criteria currently used for the diagnosis of hemophagocytic syndromes, such as HLH-2004, MAS-2005, and MAS-2016, are not sufficient for MAS in MIS-C. Our goal in this study was to work out the criteria for the early diagnosis of MAS in MIS-C. Methods: One hundred and sixty-six (166) patients with MIS-C were assessed retrospectively. The two most experienced experts independently identified patients with MAS. The patients were divided into three cohorts: MAS (n = 19), without MAS (n = 78), and probable MAS (n = 67). The latter included patients diagnosed with MAS by only one expert, and it was excluded from the analysis. Results: The age of patients with MAS was much higher, and they more frequently had edematous syndrome, hypotension and/or shock, splenomegaly, and CNS involvement. In their blood tests, thrombocytopenia, hypoalbuminemia, and hypertriglyceridemia occurred more often. The level of biomarkers of inflammation, such as ferritin, CRP, troponin, AST, and ALT, was also higher in this group. Increased fibrinogen and D-dimer were also found, demonstrating hypercoagulation in the MAS-MIS-C group. We chose 21 continuous and categorical variables with statistical significance, out of which 2-ferritin > 469 μg/L or platelets < 114 × 109/L-allowed us to discriminate MAS patients. Conclusions: Ferritin > 469 μg/L or platelets < 114 × 109/L can be regarded as key signs to differentiate MAS in MIS-C patients with a sensitivity of 100% and specificity of 94.9%, and they can be used along with other diagnostic methods.

A predictive model for Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis

Background

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a severe hyperinflammatory disorder induced by overactivation of macrophages and T cells. This study aims to identify the risk factors for the progression from infectious mononucleosis (EBV-IM) to EBV-HLH, by analyzing the laboratory parameters of patients with EBV-IM and EBV-HLH and constructing a clinical prediction model. The outcome of this study carries important clinical value for early diagnosis and treatment of EBV-HLH.

Methods

A retrospective analysis was conducted on 60 patients diagnosed with EBV-HLH and 221 patients diagnosed with EBV-IM at our hospital between November 2018 and January 2024. Participants were randomly assigned to derivation and internal validation cohorts in a 7:3 ratio. LASSO regression and logistic regression analyses were employed to identify risk factors and construct the nomogram.

Results

Ferritin (OR, 213.139; 95% CI, 8.604-5279.703; P=0.001), CD3-CD16+CD56+% (OR, 0.011; 95% CI, 0-0.467; P=0.011), anti-EBV-NA-IgG (OR, 57.370; 95%CI, 2.976-1106.049; P=0.007), IL-6 (OR, 71.505; 95%CI, 2.118-2414.288; P=0.017), IL-10 (OR, 213.139; 95% CI, 8.604-5279.703; P=0.001) were identified as independent predictors of EBV-HLH. The prediction model demonstrated excellent discriminatory capability evidenced by an AUC of 0.997 (95% CI,0.993-1.000). When visualized using a nomogram, the ROC curves for the derivation and validation cohorts exhibited AUCs of 0.997 and 0.993, respectively. These results suggested that the model was highly stable and accurate. Furthermore, calibration curves and clinical decision curves indicated that the model possessed good calibration and offered significant clinical benefits.

Conclusions

The nomogram, which was based on these five predictors, exhibited robust predictive value and stability, thereby can be used to aid clinicians in the early detection of EBV-HLH.

SARS-CoV-2 reactivates fungal-associated Hemophagocytic lymphohistiocytosis: Case report and review of the literature

Hemophagocytic lymphohistiocytosis (HLH) is a rare disease characterized by the uncontrolled activation of the immune system, resulting in a high clinical mortality rate. A 56-year-old Chinese female presented at the emergency room with symptoms including fever, fatigue, nausea, vomiting, cough, shortness of breath, and chest tightness. Laboratory investigations demonstrated decreased levels of white blood cells, hemoglobin, and platelets while interleukin-6 and ferritin exhibited significant elevations. She was subsequently admitted to the hematology department, where she was diagnosed with HLH caused by a Candida infection. Following treatment with antifungal agents, glucocorticoids, antiemetics, diuretics, and hepatoprotective therapy, the patient's condition has shown improvement. However, after being infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the patient experienced a reactivation of HLH, resulting in a more severe clinical presentation and complications compared to the initial onset. Although the patient's condition improved after the administration of antiviral drugs, etoposide, glucocorticoids, cyclosporin, and intravenous immunoglobulin, this case highlights the possibility of disease reactivation during the recovery phase of HLH. This should raise the attention of medical professionals.

Reactive hemophagocytic lymphohistiocytosis: Epidemiological, clinico-biological and etiological profile

Hemophagocytic lymphohistiocytosis (HLH) is an hyperinflammatory state resulting from increased secretion of proinflammatory cytokines, which are responsible for clinical, biological and cytological manifestations.

OBJECTIVE

The aim of our study is to describe the epidemiological, clinical, biological, etiological and evolutionary profile of HLH in Tunisia.

METHODS

A retrospective study that involved patients, with images of hemophagocytosis in myelograms analyzed at the laboratory of biological hematology of the University Hospital "Hédi-Chaker" of Sfax-Tunisia, followed at these departments: hematology, internal medicine, department of infectious-diseases and department of gastroenterology, (June2017- May2021). First, we identified all patients with hemophagocytosis images. Secondly, we selected the patients who fulfilled the diagnostic criteria of the HLH-2004-score.

RESULTS

Nineteen patients were included in this study. Nine men and 10 women with a mean age of 37.95 years. Fever was present in all patients. Organomegaly was described in 74% of cases. The most frequent cytopenia was anemia (100%). Hypertriglyceridemia was noted in 79% of cases and hyperferritinemia (> 500 ng/mL) was ubiquitous. In myelogram, 68% of patients had slides showing numerous or very numerous images of hemophagocytosis. The infectious pathology was the most common cause of HLH (42%). No cause was found in 10% of cases. The corticosteroid therapy at a dose of 1 mg/kg/day was prescribed in 89% of our patients. The overall evolution was favorable in 58% of cases. The mortality was not associated with the causal pathology (p=0.218).

CONCLUSION

Secondary HLH is likely to be under-recognized, which contributes to its high morbidity and mortality. Early recognition is crucial for any reasonable attempt at curative therapy.

A rare case of orbital inflammation complicated by hemophagocytic lymphohistiocytosis

We report a rare case of orbital inflammation complicating hemophagocytic lymphohistiocytosis (HLH) patient. HLH is a rare, life-threatening disorder characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages. A 37-year-old man known to have HLH, presented with a left periorbital swelling that was unsuccessfully treated as an orbital cellulitis, with intravenous antibiotics. A computed tomography (CT) scan of the orbits revealed inflammatory changes with no orbital collection or paranasal sinus disease. An orbital biopsy demonstrated lymphoplasmacytic infiltrations admixed with histiocytes. The patient deteriorated and was admitted to the intensive care unit. Ensuing blood results supported a diagnosis of HLH, and the patient responded well to subsequent immunosuppression. This case report highlights the importance of re-considering the diagnosis of orbital cellulitis in treatment resistant cases, particularly in the absence of sinus disease. To our knowledge, this is the third case of orbital inflammation associated with HLH patients.

A Novel Engineering Cell Therapy Platform Mimicking the Immune Thrombocytopenia-Derived Platelets to Inhibit Cytokine Storm in Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a common and highly fatal hyperinflammatory syndrome characterized by the aberrant activation of macrophages. To date, there is a lack of targeted therapies for HLH. It is validated that macrophages in HLH efficiently phagocytose anti-CD41-platelets (anti-CD41-PLTs) from immune thrombocytopenia (ITP) patients in previous research. Hence, the pathological mechanisms of ITP are mimicked and anti-CD41-PLTs are utilized to load the macrophage-toxic drug VP16 to construct macrophage-targetable engineered platelets anti-CD41-PLT-VP16, which is a novel targeted therapy against HLH. Both in vitro and in vivo studies demonstrate that anti-CD41-PLT-VP16 has excellent targeting and pro-macrophage apoptotic effects. In HLH model mice, anti-CD41-PLT-VP16 prevents hemophagocytosis and inhibits the cytokine storm. Mechanistic studies reveal that anti-CD41-PLT-VP16 increases the cytotoxicity of VP16, facilitating precise intervention in macrophages. Furthermore, it operates as a strategic "besieger" in diminishing hyperinflammation syndrome, which can indirectly prevent the abnormal activation of T cells and NK cells and reduce the Ab-dependent cell-mediated cytotoxicity effect. The first platelet-based clinical trial is ongoing. The results show that after treatment with anti-CD41-PLT-VP16, HLH patients have a threefold increase in the overall response rate compared to patients receiving conventional chemotherapy. In conclusion, anti-CD41-PLT-VP16 provides a general insight into hyperinflammation syndrome and offers a novel clinical therapeutic strategy for HLH.

Peripheral Axonal Neuropathy in Hemophagocytic Lymphohistiocytosis Secondary to Rickettsia conorii Infection

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal hyperinflammatory syndrome characterized by dysregulated immune activation and systemic inflammation. Secondary HLH is often triggered by infections, with Rickettsia conorii being an infrequently reported cause. Peripheral axonal neuropathy is a rare and poorly understood complication of HLH. We present the case of a 58-year-old male who presented with fever, diarrhea, a maculopapular rash involving the palms and soles, and progressive lower limb weakness. Laboratory findings revealed pancytopenia, hyperferritinemia, elevated soluble CD25, liver cytolysis, hypofibrinogenemia, and raised inflammatory markers. Serological testing confirmed Rickettsia conorii infection. The patient fulfilled six of the eight HLH-2004 diagnostic criteria, establishing the diagnosis of secondary HLH. Treatment was initiated with intravenous dexamethasone and doxycycline. During hospitalization, the patient developed severe hypoxemic respiratory failure, paraplegia, and acute sensory loss. The neurological evaluation confirmed peripheral axonal neuropathy linked to Rickettsia conorii infection, which preceded the development of HLH. After 21 days of doxycycline therapy, the patient was discharged to a rehabilitation facility with full neurological recovery. This case underscores the rarity of Rickettsia conorii as a trigger for HLH and highlights the exceptional occurrence of peripheral axonal neuropathy as a complication. The singularity of this case reinforces the importance of a correct and early diagnosis of HLH, which can have atypical and severe complications but also a successful outcome.

Haemophagocytic Lymphohistiocytosis Triggered by Cytomegalovirus Reactivation in An Immunosuppressed Patient with Pauci-Immune Glomerulonephritis

We report on a 67-year-old male patient admitted to the Internal Medicine department for fever, joint pain and exertional dyspnoea. Two months before his admission, the patient had been diagnosed with pauci-immune necrotising glomerulonephritis, for which he had been treated with rituximab and corticosteroids. Upon admission the patient was stable, but within a few hours he became unstable as liver failure and acute cytopaenia occurred. Blood investigations revealed cytopaenia, altered coagulation tests, high ferritin, triglycerides, lactate dehydrogenase and C-reactive protein levels, and severe cytocholestasis. A liver echography was normal. The patient had been transferred to the intensive care unit to receive supportive support when the cytomegalovirus polymerase chain reaction (CMV-PCR) test came back positive. The diagnosis of haemophagocytic lymphohistiocytosis associated with a CMV infection and/or reactivation in an immunosuppressed patient was made. Specific treatment was administrated, along with symptomatic treatment. The patient clinically improved during hospitalisation with complete resolution of symptoms.

LEARNING POINTS

Haemophagocytic lymphohistiocytosis (HLH) is a rare disease yet important to diagnose, as it is quickly life-threatening.The diverse symptoms of HLH can make diagnosis tricky, with many potential causes. As clinical presentation is not very specific, it is often mistaken for infection with severe sepsis and its diagnosis is often delayed.Limited understanding of this condition could lead to worse outcomes for patients. Recognising it early is crucial for starting the right treatment and enhancing both the well-being and survival chances of those affected by this complex disorder.In practice, HLH must be suspected when bi/pancytopaenia occurs in a patient presenting a high fever of unknown cause, especially when they have a history of immunosuppression. Managing it often requires a range of approaches, such as intensive care, immune system suppression, specialised medications or even stem cell transplants.

Transplantation in adult patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis: yes or no?

ABSTRACT

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome characterized by aberrant immunological activity with a dismal prognosis. Epstein-Barr virus (EBV)-associated HLH (EBV-HLH) is the most common type among adults. Patients with EBV infection to B cells could benefit from rituximab, whereas lethal outcomes may occur in patients with EBV infection to T cells, nature killer cells, or multilineages. The necessity of allogeneic hematopoietic stem cell transplantation (HSCT) in adult patients with EBV-HLH remains controversial. A total of 356 adult patients with EBV-HLH entered this study. Eighty-eight received HSCT under medical recommendation. Four received salvage HSCT. The 5-year overall survival (OS) rate for patients who underwent HSCT was 48.7% (vs 16.2% in patients who did not undergo transplantation; P < .001). There was no difference in OS between patients who received transplantation at first complete response (CR1) and those at first partial response (PR1) nor between patients at CR1 and CR2. Patients who received transplantation at PR2 had inferior survival. The rate of reaching CR2 was significantly higher in patients with CR1 than PR1 (P = .014). Higher soluble CD25 levels, higher EBV-DNA loads in plasma after HSCT, poorer remission status, more advanced acute graft-versus-host disease (GVHD), and the absence of localized chronic GVHD were associated with inferior prognosis (P < .05). HSCT improved the survival of adult EBV-HLH significantly. For patients who achieved PR after initial treatment, HSCT was recommended. A wait-and-see strategy could be adopted for patients who achieved CR after initial treatment but with the risk of failing to achieve CR2.

Comprehensive mapping of immune perturbations associated with secondary hemophagocytic lymphohistiocytosis

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

Utility of N-acetylcysteine in Non-Acetaminophen-Induced Liver Injury Secondary to Influenza A Infection

Influenza A, which belongs to the Orthomyxoviridae viral family, is a known causative agent of respiratory illness and systemic inflammation. Annual influenza immunizations are crucial in reducing the incidence and severity of the flu. Intravenous (IV) N-acetylcysteine (NAC) is a pharmaceutical agent indicated for hepatic injury, particularly to address oxidative stress and inflammation secondary to acetaminophen toxicity. The authors present a case of a young female with acute liver injury and impending liver failure in the setting of viral influenza A infection, successfully treated with IV-NAC.

Emapalumab as a therapeutic intervention for Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis: A case series

RATIONALE

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is characterized by a severe cytokine storm, heightened inflammatory response, and immune-mediated damage to tissues and organs. Standard treatment protocols for hemophagocytic lymphohistiocytosis often fall short in effectively controlling EBV-HLH, leading to a need for novel therapeutic options. Emapalumab, a monoclonal antibody targeting interferon-gamma, has shown promise due to its targeted cytokine modulation capabilities and favorable safety profile. This study aimed to evaluate the efficacy and safety of emapalumab in pediatric patients with EBV-HLH.

PATIENT CONCERNS

The case series involved 4 pediatric patients diagnosed with EBV-HLH who did not achieve disease control despite receiving comprehensive treatment.

DIAGNOSES

All 4 pediatric patients were diagnosed with EBV-HLH.

INTERVENTIONS

Emapalumab was introduced as an adjunctive therapeutic intervention alongside the HLH-94 or L-DEP regimens for these patients.

OUTCOMES

Among the 4 patients, 1 experienced severe multiorgan dysfunction and opted to discontinue therapy. The remaining 3 patients showed controlled disease progression with significant clinical improvements following emapalumab administration. These improvements included reduced levels of inflammatory markers, normalization of blood counts and liver function, and decreased Epstein-Barr virus viral load.

LESSONS

The findings suggest that emapalumab may be an effective and safe treatment option for pediatric EBV-HLH. However, further research is necessary to confirm these outcomes, especially in critically ill patients.

From Diagnosis to Treatment: A Successful Case of Haemophagocytic Lymphohistiocytosis of Presumed Bacterial Aetiology in an Adult

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

LEARNING POINTS

Haemophagocytic lymphohistiocytosis is characterised as a rare inflammatory syndrome that occurs due to uncontrolled systemic immune activation.Timely diagnosis and treatment are essential, as mortality is still high.

Enhancing diagnostic precision in EBV-related HLH: a multifaceted approach using 18F-FDG PET/CT and nomogram integration

BACKGROUND

The hyperinflammatory condition and lymphoproliferation due to Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (HLH) affect the detection of lymphomas by 18F-FDG PET/CT. We aimed to improve the diagnostic capabilities of 18F-FDG PET/CT by combining laboratory parameters.

METHODS

This retrospective study involved 46 patients diagnosed with EBV-positive HLH, who underwent 18F-FDG PET/CT before beginning chemotherapy within a 4-year timeframe. These patients were categorized into two groups: EBV-associated HLH (EBV-HLH) (n = 31) and EBV-positive lymphoma-associated HLH (EBV + LA-HLH) (n = 15). We employed multivariable logistic regression and regression tree analysis to develop diagnostic models and assessed their efficacy in diagnosis and prognosis.

RESULTS

A nomogram combining the SUVmax ratio, copies of plasma EBV-DNA, and IFN-γ reached 100% sensitivity and 81.8% specificity, with an AUC of 0.926 (95%CI, 0.779-0.988). Importantly, this nomogram also demonstrated predictive power for mortality in EBV-HLH patients, with a hazard ratio of 4.2 (95%CI, 1.1-16.5). The high-risk EBV-HLH patients identified by the nomogram had a similarly unfavorable prognosis as patients with lymphoma.

CONCLUSIONS

The study found that while 18F-FDG PET/CT alone has limitations in differentiating between lymphoma and EBV-HLH in patients with active EBV infection, the integration of a nomogram significantly improves the diagnostic accuracy and also exhibits a strong association with prognostic outcomes.

Hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis: A case report of a rare complication of visceral leishmaniasis

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially life-threatening clinical syndrome characterized by hyperactivation of inflammatory mediators and harmful end-organ damage. Visceral leishmaniasis (VL)-induced HLH is a rare disease with significant diagnostic and management implications. Herein, we present a case of secondary HLH as a complication of visceral leishmaniasis in a two-year-old toddler. A 2-year-old male toddler was admitted for evaluation of a prolonged 4-week fever. Accompanying the fever, he developed progressive abdominal swelling, intermittent bilateral nasal bleeding, and repeated chest-focus infections of similar duration. The patient was acutely sick, with chronic signs of malnutrition (mid-upper arm circumference of 10.5 cm), fever (39 °C), tachypnea (70 breaths/min), tachycardia (132 beats/min), pallor, and hepatosplenomegaly. Initial investigation revealed leukopenia (2240/μl), anemia (7.3 g/dl), and severe thrombocytopenia (26,000/μl). With consideration of febrile neutropenia, the patient was started on cefepime with further revision to vancomycin and meropenem based on the culture result. After 10 days of persistent fever and poor clinical condition, an immunochromatographic rapid test with the rK39 antigen was conducted, and the patient was found to be positive for Leishmania spp. Intravenous liposomal amphotericin B (AmBisome) was initiated. On the 6th day of treatment, the patient's clinical and laboratory profiles severely deteriorated, and further laboratory investigation showed elevated triglyceride (524 mg/dl) and ferritin levels (1500 ng/mL). VL-induced secondary HLH was confirmed, and intravenous dexamethasone was initiated. Subsequently, his clinical and laboratory findings significantly improved, and he was discharged with PO dexamethasone. Our case highlights the intricate nature of VL-induced HLH and the need for high index of suspicion and timely management.

A Case Report of Hemophagocytic Lymphohistiocytosis Masquerading as Sepsis

Profound inflammation due to cytokine storm is often the underlying cause of death in patients with hemophagocytic lymphohistiocytosis (HLH). Sepsis, while a precipitant, is also the great masquerader that may hide early signs of HLH. Prompt recognition is important to prevent rapid clinical decline and death. A patient presented with two weeks of unremitting fever of 103°F, dysuria, bilateral flank pain, and confusion. Obstructive uropathy and pyelonephritis were treated with a Foley catheter and antibiotics. There were abnormal developments during his hospitalization including a deep vein thrombus despite prophylactic anticoagulation. Antibiotics and Foley management did not improve fevers or renal injury so he eventually required continuous renal replacement therapy and blood product transfusions. In rapid progression, the patient developed pancytopenia, neutropenia, hyperferritinemia, hypertriglyceridemia, and hypofibrinogenemia suspicious for HLH. A bone marrow biopsy was consistent with progressive T-cell lymphoma, the likely cause of secondary HLH. Antineoplastics, corticosteroids, and opportunistic prophylaxis were pursued. Unfortunately, the cytopenias worsened, and the patient developed shock with hypoxemia and hypotension, followed by cardiac arrest and demise.

Hemophagocytic Lymphohistiocytosis Gene Variants in Severe Aplastic Anemia and Their Impact on Hematopoietic Cell Transplantation Outcomes

Germline genetic testing for patients with severe aplastic anemia (SAA) is recommended to guide treatment, including the use of immunosuppressive therapy and/or adjustment of hematopoietic cell transplantation (HCT) modalities. Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory condition often associated with cytopenias with autosomal recessive (AR) or X-linked recessive (XLR) inheritance. HLH is part of the SAA differential diagnosis, and genetic testing may identify variants in HLH genes in patients with SAA. The impact of pathogenic/likely pathogenic (P/LP) variants in HLH genes on HCT outcomes in SAA is unclear. In this study, we aimed to determine the frequency of HLH gene variants in a large cohort of patients with acquired SAA and to evaluate their association(s) with HCT outcomes. The Transplant Outcomes in Aplastic Anemia project, a collaboration between the National Cancer Institute and the Center for International Blood and Marrow Transplant Research, collected genomic and clinical data from 824 patients who underwent HCT for SAA between 1989 and 2015. We excluded 140 patients with inherited bone marrow failure syndromes and used exome sequencing data from the remaining 684 patients with acquired SAA to identify P/LP variants in 14 HLH-associated genes (11 AR, 3 XLR) curated using American College of Medical Genetics and Genomics/Association of Molecular Pathology (ACMG/AMP) criteria. Deleterious variants of uncertain significance (del-VUS) were defined as those not meeting the ACMG/AMP P/LP criteria but with damaging predictions in ≥3 of 5 meta-predictors (BayesDel, REVEL, CADD, MetaSVM, and/or EIGEN). The Kaplan-Meier estimator was used to calculate the probability of overall survival (OS) after HCT, and the cumulative incidence calculator was used for other HCT outcomes, accounting for relevant competing risks. There were 46 HLH variants in 49 of the 684 patients (7.2%). Seventeen variants in 19 patients (2.8%) were P/LP; 8 of these were loss-of-function variants. Among the 19 patients with P/LP HLH variants, 16 (84%) had monoallelic variants in genes with AR inheritance, and 3 had variants in XLR genes. PRF1 was the most frequently affected gene (in 8 of the 19 patients). We found no statistically significant differences in transplantation-related factors between patients with and those without P/LP HLH variants. The 5-year survival probability was 89% (95% confidence interval [CI], 72% to 99%) in patients with P/LP HLH variants and 70% (95% CI, 53% to 85%) in those with del-VUS HLH variants, compared to 66% (95% CI, 62% to 70%) in those without variants (P = .16, log-rank test). The median time to neutrophil engraftment was 16 days for patients with P/LP HLH variants and 18 days in those with del-VUS HLH variants or without variants combined (P = .01, Gray's test). No statistically significant associations between P/LP HLH variants and the risk of acute or chronic graft-versus-host disease were noted. In this large cohort of patients with acquired SAA, we found that 2.8% of patients harbored a P/LP variant in an HLH gene. No negative effects of HLH gene variants on post-HCT survival were noted. The small number of patients with P/LP HLH variants limits the study's ability to provide conclusive evidence; nonetheless, our data suggest that there is no need for special transplantation considerations for patients with SAA carrying P/LP variants.

Hemophagocytic lymphohistiocytosis secondary to rifampin treatment: A case report

RATIONALE

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening systemic inflammatory syndrome characterized by an overactive immune response. This hyperactivation can arise from genetic mutations, infections, malignancies, or autoimmune disorders. Medication-induced HLH is extremely rare and requires special attention.

PATIENT CONCERNS

A 53-year-old female diagnosed with pulmonary and urinary tract tuberculosis. She underwent quadruple therapy, including isoniazid, rifampin, ethambutol, and pyrazinamide. Subsequently, she developed fever, hepatosplenomegaly, pancytopenia, hypertriglyceridemia, hypofibrinogenemia, hyperferritinemia, increased soluble CD25 levels, decreased natural killer cell activity, and hemophagocytosis, notably without eosinophilia. Her clinical symptoms were exacerbated by rifampin intake.

DIAGNOSES

Pulmonary and left kidney tuberculosis, multiple organ failure, and rifampin-induced HLH.

INTERVENTIONS

Anti-tuberculosis regimen (isoniazid, pyrazinamide, ethambutol, and levofloxacin, excluding rifampin) combined with glucocorticoid therapy.

OUTCOMES

Satisfactory recovery with improved clinical symptoms, laboratory tests, and chest imaging studies.

LESSONS

Early correct diagnosis and appropriate management of HLH are essential to save the lives of affected patients. The potential severe side effects of rifampin should not be ignored.

The efficacy and safety of chidamide in combination with etoposide and glucocorticoids for the treatment of hemophagocytic lymphohistiocytosis in adult patients: an open-label, single-center study

Background

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition characterized by hyperinflammation and organ failure, with a high mortality rate. Current first-line treatments for adult patients have limited efficacy and significant toxicity. The novel selective histone deacetylase inhibitor (HDACi), chidamide, has shown promise in preclinical studies for the potential treatment of HLH.

Methods

An open-label, single-center study was conducted to evaluate the efficacy and safety of chidamide in combination with etoposide and glucocorticoids for the treatment of HLH in adult patients. Seventeen patients who fulfilled at least five of the eight HLH-2004 criteria were enrolled and treated with the combination therapy. The primary outcome was overall response rate (ORR), and secondary outcomes included survival, safety and tolerability, and changes in laboratory indicators.

Results

A total of 17 HLH patients who met the inclusion criteria were enrolled in this study, with a male to female ratio of 1.8:1. The age range at enrollment was 31 to 71 years old, with a median age of 52 years old. The ORR was 76.5% (13/17 patients), with a complete response (CR) rate of 17.6% (3/17 patients) and a partial response (PR) rate of 58.8% (10/17 patients). The median overall survival (OS) was not achieved, with OS at 6 months and 12 months being 81% and 65%, respectively. The median progression free survival (PFS) was not achieved, with PFS at 6 months and 12 months being 68% and 55%, respectively. Hematologic toxicities is the most common. Safety profile was favorable, with very few cases of grade 3/4 toxicities observed. The results showed that the levels of sCD25, platelets, aspartate aminotransferase, lactate dehydrogenase, and albumin in these patients were significantly improved 3 weeks after treatment.

Conclusion

The addition of chidamide to etoposide and glucocorticoids may be a promising new treatment option for patients with HLH, with a high ORR, manageable safety profile, and significant improvement in laboratory indicators. Further research is needed to confirm these findings and determine the optimal dosing and duration of therapy.

Macrophage-Biomimetic Nanoplatform-Based Therapy for Inflammation-Associated Diseases

Inflammation-associated diseases are very common clinically with a high incidence; however, there is still a lack of effective treatments. Cell-biomimetic nanoplatforms have led to many breakthroughs in the field of biomedicine, significantly improving the efficiency of drug delivery and its therapeutic implications especially for inflammation-associated diseases. Macrophages are an important component of immune cells and play a critical role in the occurrence and progression of inflammation-associated diseases while simultaneously maintaining homeostasis and modulating immune responses. Therefore, macrophage-biomimetic nanoplatforms not only inherit the functions of macrophages including the inflammation tropism effect for targeted delivery of drugs and the neutralization effect of pro-inflammatory cytokines and toxins via membrane surface receptors or proteins, but also maintain the functions of the inner nanoparticles. Macrophage-biomimetic nanoplatforms are shown to have remarkable therapeutic efficacy and excellent application potential in inflammation-associated diseases. In this review, inflammation-associated diseases, the physiological functions of macrophages, and the classification and construction of macrophage-biomimetic nanoplatforms are first introduced. Next, the latest applications of different macrophage-biomimetic nanoplatforms for the treatment of inflammation-associated diseases are summarized. Finally, challenges and opportunities for future biomedical applications are discussed. It is hoped that the review will provide new ideas for the further development of macrophage-biomimetic nanoplatforms.

Early Diagnosis of Hemophagocytic Lymphohistiocytosis in an Adult Presenting With Sickle Cell Disease: A Case Report

Hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially life-threatening syndrome characterized by excessive immune activation and tissue inflammation. This case report describes the early diagnosis of HLH in an adult patient who initially presented with a febrile syndrome associated with low back pain. The patient, a 33-year-old male, exhibited bicytopenia, hepatosplenomegaly, and hyperferritinemia without a previous diagnosis of sickle cell disease (SCD). Diagnostic challenges arose due to the overlapping clinical manifestations of SCD and HLH and their uncommon association. However, timely recognition and intervention were achieved through comprehensive diagnostic evaluations, including a bone marrow biopsy. The patient was promptly started on an appropriate therapeutic regimen, which led to significant clinical improvement. This case underscores the importance of considering HLH in the differential diagnosis of adults presenting with hematologic abnormalities and systemic inflammation. Early diagnosis and treatment are critical to improving outcomes for patients with this complex and severe disorder.

Humanization with CD34-positive hematopoietic stem cells in NOG-EXL mice results in improved long-term survival and less severe myeloid cell hyperactivation phenotype relative to NSG-SGM3 mice

NSG-SGM3 and NOG-EXL mice combine severe immunodeficiency with transgenic expression of human myeloid stimulatory cytokines, resulting in marked expansion of myeloid populations upon humanization with CD34+ hematopoietic stem cells (HSCs). Humanized NSG-SGM3 mice typically develop a lethal macrophage activation syndrome and mast cell hyperplasia that limit their use in long-term studies (e.g., humanization followed by tumor xenotransplantation). It is currently unclear to what extent humanized NOG-EXL mice suffer from the same condition observed in humanized NSG-SGM3 mice. We compared the effects of human CD34+ HSC engraftment in these two strains in an orthotopic patient-derived glioblastoma model. NSG-SGM3 mice humanized in-house were compared to NOG-EXL mice humanized in-house and commercially available humanized NOG-EXL mice. Mice were euthanized at humane or study endpoints, and complete pathological assessments were performed. A semiquantitative multiparametric clinicopathological scoring system was developed to characterize chimeric myeloid cell hyperactivation (MCH) syndrome. NSG-SGM3 mice were euthanized at 16 weeks after humanization because of severe deterioration of clinical conditions. Humanized NOG-EXL mice survived to the study endpoint at 22 weeks after humanization and showed less-severe MCH phenotypes than NSG-SGM3 mice. Major differences included the lack of mast cell expansion and limited tissue/organ involvement in NOG-EXL mice compared to NSG-SGM3 mice. Engraftment of human lymphocytes, assessed by immunohistochemistry, was similar in the two strains. The longer survival and decreased MCH phenotype severity in NOG-EXL mice enabled their use in a tumor xenotransplantation study. The NOG-EXL model is better suited than the NSG-SGM3 model for immuno-oncology studies requiring long-term survival after humanization.

Clinical and Biochemical Characteristics of Hemophagocytic Lymphohistiocytosis in People Living With HIV and Disseminated Histoplasmosis at a Tertiary Hospital in Mexico

Background

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.

Methods

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.

Results

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%.

Conclusions

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.

Performances of the H-score and the HLH-2004 score in the positive diagnosis of secondary hemophagocytic lymphohistiocytosis

Hemophagocytic lymphocytosis (HLH) is a rare clinical and biological entity that can be life-threatening. Early diagnosis can improve the overall prognosis of HLH.

OBJECTIVES

The aims of this study are to evaluate the performances of HLH-2004-score and H-score in identifying patients with secondary HLH and to determine an optimal H-score cut-off for our population.

METHODS

A retrospective study that involved all patients, with images of hemophagocytosis in myelograms analyzed at the laboratory of hematology, followed at these departments: clinical-hematology, internal-medicine, infectious-diseases and gastroenterology, University-Hospital "Hédi-Chaker", Sfax-Tunisia, (June2017-May2021). We identified two groups of patients: "HLH" and "Not-HLH". Then, for each patient, we calculated the HLH-2004-score and the H-score.

RESULTS

Forty-two patients were included in this study. Twenty-five (60 %) belonging to group "HLH" and seventeen (40 %) to group "Not-HLH" with a mean age (38.72 vs. 39.82 years, p = 0.846) respectively. The study of the performances demonstrated that H-score had better performances. The best cut-off value of H-score for our population was 158.5, allowing a gain in sensitivity (from 92 % to 96 %) compared to the original study cut-off of 169.

CONCLUSION

Both H-score and HLH-2004-score showed excellent discriminative powers with better performances for H-score. The new H-score cut-off at 158.5 can be applied to our population.

Outcome and Prognostic Factors of Hemophagocytic Lymphohistiocytosis in Children: Experience From a Low- and Middle-Income Country

Objective Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition especially in low- and middle-income countries (LMICs). This study was done to evaluate the outcome and prognostic factors of HLH in patients presenting to our center. Methods The study was carried out at the Paediatric Oncology Department of Combined Military Hospital (CMH) in Rawalpindi, Pakistan. All cases of HLH, from one month to 15 years of age enrolled between January 1, 2013 to June 30, 2023, were included. IBM SPSS Statistics for Windows, version 25.0 (released 2017, IBM Corp., Armonk, NY) was used for statistical analysis, and t-test and chi-square tests were used for comparison between continuous and categorical variables. Frequencies and percentages were calculated for categorical variables. Results Out of 115 patients, seven (6%) abandoned the treatment. The data of 108 cases, including 58 males (53.7%), were analyzed. The mean age at diagnosis was 31.5 ± 39.03 months. The mean time to reach a pediatric oncologist was 30.20 ± 22.15 days. Fever and pallor were common symptoms occurring in 107 (99.1%) and 98 (90.7%) cases, respectively. Jaundice was present in 44 (40.7%), visceromegaly in 64 (59.3%), and bruising/bleeding in 16 cases (14.8%). Twenty-six (24.1%) patients underwent hematopoietic stem cell transplant (HSCT), out of which 17 (65.4%) children were cured. Overall survival at two years, five years, and 10 years was 38%, 37%, and 36.1%, respectively. Disease-free survival at two years, five years, and 10 years was 33.3%, 32.4%, and 31.5%, respectively. Conclusion HLH leads to high mortality due to delayed or misdiagnosis in LMICs. Early diagnosis and early referral to a pediatric oncologist is the detrimental factor in survival for HLH. HSCT is the treatment of choice for primary, refractory, or relapse cases.

Diagnosis of Hemophagocytic Lymphohistiocytosis in Pyrexia of Unknown Origin: A Case Report

ABSTRACT

A case of a 61-year male presented with chief complaints of fever for three months. Diagnosis of hemophagocytic lymphohistiocytosis was made after liver biopsy when Positron-Emission Tomography revealed multiple fluoro deoxy glucose avid lesions in the liver. The patient of this disease typically presents with fever, splenomegaly, hyperferritinemia, hypertriglyceridemia, raised liver enzymes, and marrow features suggestive of hemophagocytosis. The treatment is usually systemic corticosteroids, chemotherapy with etoposide, cyclosporine, or hematopoietic stem cell transplantation, depending on the cause. A diagnosis like hemophagocytic lymphohistiocytosis can easily be missed in developing countries with low resources like Nepal. Hence, this disease should be suspected in patients presenting with pyrexia of unknown origin by treating physicians.

Hemophagocytic syndrome related by EBV infection: case report

A 34-year-old woman of Asian origin with diffuse lymphadenopathy and hepatosplenomegaly in hemophagocytic syndrome induced by Epstein Barr Virus (EBV) infection. The rapidity of progression of clinical manifestations lead to early orotracheal intubation and death due to multiple organ failure (MOF).

Secondary hemophagocytic syndrome in an acquired immunodeficiency syndrome and Alpha-thalassemia patient infected with Talaromyces marneffei: A case report and literature review

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease characterized by a hyperinflammatory syndrome and impairment of multiple organ systems. Talaromycosis marneffei (TSM) is an opportunistic infection mostly found in immunosuppressed populations, such as those with acquired immunodeficiency syndrome (AIDS), and is prevalent in southern China. However, HLH secondary to TSM is extremely rare and has only been reported in isolated cases. A 30-year-old patient with recurrent high fever and progressive cytopenia was diagnosed with HLH secondary to disseminated TSM with AIDS and Alpha-thalassemia. The patient remained in sustained remission without recurrence after effective treatment with antifungals and glucocorticoids.

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS): contemporary advances and current controversies

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an inflammatory syndrome with characteristic clinical, radiological, and pathological features, and can be effectively treated with corticosteroid-based immunotherapies. The exact pathogenesis of CLIPPERS remains unclear, and specific diagnostic biomarkers are not available. According to the 2017 diagnostic criteria, probable CLIPPERS should be considered in middle-aged patients with subacute onset of pontocerebellar symptoms and typical punctuate and curvilinear gadolinium enhancement lesions ("salt-and-pepper" appearance) located in the hindbrain (especially pons) on magnetic resonance imaging. In addition, CLIPPERS-mimics, such as central nervous system (CNS) lymphoma, and several antibody-associated autoimmune CNS diseases (e.g., myelin oligodendrocyte glycoprotein antibody-associated disease, autoimmune glial fibrillary acidic protein astrocytopathy, and anti-N-methyl-D-aspartate receptor encephalitis), should be extensively excluded. The prerequisite for definite CLIPPERS is the perivascular T-cell-predominant inflammatory infiltration observed on pathological analysis. A biopsy is strongly suggested when clinical/radiological red flags are present. Most patients with CLIPPERS respond well to corticosteroids and have a good prognosis. Long-term low-dose corticosteroid maintenance therapy or corticosteroids coupled with immunosuppressants are recommended to prevent the recurrence of the syndrome. The potential progression of CLIPPERS to lymphoma has been suggested in some cases; therefore, at least 2-year clinical and radiological follow-up is essential. Here, we critically review the recent developments and provided an update on the clinical characteristics, diagnostic criteria, differential diagnoses, and therapeutic management of CLIPPERS. We also discuss the current controversies in this context that can be resolved in future research studies.

Germline HAVCR2/TIM-3 Checkpoint Inhibitor Receptor Deficiency in Recurrent Autoinflammatory Myocarditis

Myocarditis can be caused by viral infection, drug reaction or general inflammatory condition. To provide understanding on inflammatory myocarditis, we describe clinical, genetic, and immunological properties of a young male patient who suffered from recurrent myocarditis episodes since the age of four years. Electrocardiography, troponin I/T, echocardiography, myocardial magnetic resonance imaging and histological findings were consistent with recurrent myocarditis episodes. Homozygous c.245 A > G p.Tyr82Cys pathogenic variant in Hepatitis A Virus Cellular Receptor 2 (HAVCR2) gene encoding T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) receptor was found. Peripheral blood mononuclear cells were collected when the patient was asymptomatic; CD4+ and CD8+ T lymphoblasts, CD56+ natural killer cells and CD14+ monocytes were negative for surface TIM-3 expression. In vitro, TLR4 mediated interleukin-1β (IL-1β) response was high after LPS/ATP stimulation. Clinical symptoms responded to IL-1 receptor antagonist anakinra. TIM-3 p.Tyr82Cys CD4+ and CD8+ T cell proliferation in vitro was unrestrained. Findings on IL-2, interferon gamma, regulatory T cells, signal transducer and activator of transcription (STAT) 1, 3 and 4 phosphorylation, and PD-1 and LAG-3 checkpoint inhibitor receptor analyses were comparable to controls. We conclude that TIM-3 deficiency due to homozygous HAVCR2 c.245 A > G p.Tyr82Cys pathogenic variant in the patient described here is associated with autoinflammatory symptoms limited to early onset recurrent febrile myocarditis. Excessive IL-1β production and defective regulation of T cell proliferation may contribute to this clinical condition responsive to anakinra treatment.

Probable secondary hemophagocytic lymphohistiocytosis manifesting as central nervous system lesions after COVID-19 vaccination: a case report

Background

Hemophagocytic lymphohistiocytosis (HLH) is a rare systemic inflammatory disease commonly characterized by histiocyte infiltration in multiple organs, such as the liver, spleen, lymph nodes, bone marrow, and central nervous system. The clinical features of HLH include fever, splenomegaly, cytopenia, hypertriglyceridemia, hypofibrinogenemia, and elevated blood ferritin levels. HLH is categorized as either primary or secondary. Coronavirus disease 2019 (COVID-19) vaccines may occasionally trigger secondary HLH, which is related to hyperinflammatory syndrome.

Case presentation

A 58-year-old woman, previously diagnosed with Graves' disease, presented with cognitive decline 2 weeks after receiving the first dose of the ChAdOx1 nCoV-19 vaccine. Brain MRI revealed a hyperintense lesion on T2-weighted and fluid-attenuated inversion recovery images in the bilateral subcortical white matter and right periventricular area. Vaccination-associated acute disseminated encephalomyelitis was suspected and methylprednisolone and intravenous immunoglobulin (IVIg) were administered. From the 5th day of IVIg administration, the patient developed fever and pancytopenia. In the findings of bone marrow biopsy, hemophagocytosis was not observed; however, six of the eight diagnostic criteria for HLH-2004 were met, raising the possibility of HLH. Although there was no definitive method to confirm causality, considering the temporal sequence, suspicion arose regarding vaccine-induced HLH. Splenectomy was considered for therapeutic and diagnostic purposes; however, the patient died on the 28th day of hospitalization owing to multiple organ failure.

Conclusion

To date, 23 cases of COVID-19 vaccine-related HLH have been reported. Additionally, HLH in COVID-19 patients has been reported in various case reports. To the best of our knowledge, this is the first reported case of central nervous system involvement in HLH related to any type of COVID-19 vaccine. This case suggests that even when there are no systemic symptoms after COVID-19 vaccination, HLH should be considered as a differential diagnosis if brain lesions are suggestive of CNS demyelinating disease.

Hemophagocytic Lymphohistiocytosis (HLH) Flare Following the COVID-19 Vaccine: A Case Report

Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory state that leads to overactivation of the immune system due to underlying disease. It can lead to multiorgan failure and death if not treated properly. HLH after vaccination is rare but has been reported in a few cases. Here, we present a case of a patient who developed HLH after she received the COVID-19 vaccine. Workup was done to find the underlying cause of her symptoms. However, as all investigations yielded negative results, the close temporal association with the COVID-19 vaccine suggested that the vaccine might have been the causative factor. She was treated appropriately with steroids and discharged with follow-up appointments. The exact pathogenesis of HLH caused by COVID vaccine is unknown, but it is likely related to the inflammatory response caused by the vaccine in the body. The treatment of HLH depends on the treatment of underlying conditions causing the HLH. Very few cases have been reported in the literature regarding HLH caused by COVID vaccine. Immediate recognition and treatment are imperative for improved prognosis and improved chances of survival.

Hemophagocytic Lymphohistiocytosis (HLH) in Patients with Tick-Borne Illness: A Scoping Review of 98 Cases

Hemophagocytic lymphohistiocytosis (HLH) secondary to tick-borne infections is a rare but potentially life-threatening syndrome. We performed a scoping review according to PRISMA guidelines to systematically analyze the existing literature on the topic. A total of 98 patients were included, with a mean age of 43.7 years, of which 64% were men. Most cases, 31%, were reported from the USA. Immunosuppression was present in 21.4%, with the most common cause being previous solid organ transplantation. Constitutional symptoms were the most common, observed in 83.7% of the patients, while fever was reported in 70.4% of cases. Sepsis was present in 27.6%. The most common laboratory abnormalities in this cohort were thrombocytopenia in 81.6% of patients, while anemia, leukopenia, and leukocytosis were observed in 75.5%, 55.1%, and 10.2%, respectively. Liver enzyme elevation was noted in 63.3% of cases. The H-score was analyzed in 64 patients, with the mean value being 209, and bone marrow analysis was performed in 61.2% of patients. Ehrlichia spp. was the main isolated agent associated with HLH in 45.9%, followed by Rickettsia spp. in 14.3% and Anaplasma phagocytophilum in 12.2%. Notably, no patient with Powassan virus infection or Lyme borreliosis developed HLH. The most common complications were acute kidney injury (AKI) in 35.7% of patients, shock with multiple organ dysfunction in 22.5%, encephalopathy/seizure in 20.4%, respiratory failure in 16.3%, and cardiac complications in 7.1% of patients. Treatment included antibiotic therapy alone in 43.9%, while 5.1% of patients were treated with immunosuppressants alone. Treatment with both antibiotics and immunosuppressants was used in 51% of patients. Appropriate empiric antibiotics were used in 62.2%. In 43.9% of cases of HLH due to tick-borne disease, patients received only antimicrobial therapy, and 88.4% of those recovered completely without the need for immunosuppressive therapy. The mortality rate in our review was 16.3%, and patients who received inappropriate or delayed empiric therapy had a worse outcome. Hence, we suggest empiric antibiotic treatment in patients who are suspected of having HLH due to tick-borne disease or in whom diagnostic uncertainty persists due to diagnostic delay in order to minimize mortality.

Using HScore for Evaluation of Hemophagocytosis in Multisystem Inflammatory Syndrome Associated with COVID-19 in Children

Hemophagocytic syndrome is a key point in the pathogenesis of severe forms of multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C). The factors associated with hemophagocytosis in patients with MIS-C were assessed in the present study of 94 boys and 64 girls ranging in age from 4 months to 17 years, each of whose HScore was calculated. In accordance with a previous analysis, patients with HScore ≤ 91 (n = 79) and HScore > 91 (n = 79) were compared. Patients with HScore > 91 had a higher frequency of symptoms such as cervical lymphadenopathy, dry cracked lips, bright mucous, erythema/swelling of hands and feet, peeling of fingers, edematous syndrome, hepatomegaly, splenomegaly, and hypotension/shock. They also had a higher erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and D-dimer levels, and a tendency to anemia, thrombocytopenia, and hypofibrinogenemia. They more often needed acetylsalicylic acid and biological treatment and were admitted to ICU in 70.9% of cases. Conclusion: The following signs of severe MIS-C were associated with HScore > 91: myocardial involvement, pericarditis, hypotension/shock, and ICU admission.

Pediatric hemophagocytic lymphohistiocytosis after concomitant administration of SARS-CoV-2 vaccine and influenza vaccine

Hemophagocytic lymphohistiocytosis (HLH) is a highly lethal disease characterized by fever, cytopenia, splenomegaly, and hemophagocytosis. Whereas infectious diseases, malignant tumors, and autoimmune diseases are often triggers for HLH, reports of HLH associated with vaccination are limited. In this report, we describe a case of HLH in a 12-year-old female patient after simultaneous administration of the bivalent messenger RNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine and quadrivalent inactivated influenza vaccine. The patient presented to our hospital with fever on the day after vaccination. Considering the splenomegaly, cytopenia, hemophagocytosis in the bone marrow, and high ferritin level, HLH was diagnosed 12 days after vaccination. Various tests ruled out any infectious disease, malignant tumor, or autoimmune disease. The patient was treated only with 2 mg/kg/day of oral prednisolone, fever improved 13 days after vaccination, and blood test findings rapidly improved. Although HLH after SARS-CoV-2 vaccination or concomitant administration with influenza vaccination is still rare, we emphasize the importance of early HLH diagnosis when persistent fever is observed following vaccination.

Clinical characteristics of hemophagocytic lymphohistiocytosis

BACKGROUND

There is no specificity in the clinical presentation of hemophagocytic lymphohistiocytosis (HLH).

OBJECTIVE

To study some clinical, etiological, and prognostic features of HLH to improve the clinical understanding of the disease.

METHODS

Retrospective analysis of the clinical data of 125 patients with HLH admitted to our hospital from June 2015 to August 2021, including clinical characteristics, laboratory indicators, and survival period. Statistical analysis was performed from the overall group of study indicators, which included population, children, and adults.

RESULTS

In the whole population, sex, age, blood myoglobin, and NK cell ratio of M-HLH and non-M-HLH patients (P< 0.05), serum albumin, and direct bilirubin were independent correlates of M-HLH. In the pediatric group, age and the proportion of NK cells were significantly different between M-HLH and non-M-HLH patients (P< 0.05). Multivariate Logistic regression analysis showed that all factors were not significantly associated with M-HLH. The associated regression analysis showed that all factors were not significantly associated with M-HLH. ROC curve analysis showed that the best predictive value of NK cell percentage for M-HLH diagnosis in the overall population was 4.96% in the pediatric group and 4.96% in the adult group. The best predictive value for M-HLH diagnosis was 2.08%. The univariate analysis showed that platelet count, alanine aminotransferase, aspartate aminotransferase, serum albumin, direct bilirubin and indirect bilirubin affected prognosis; COX regression showed that none of these factors had a significant relationship. The overall median survival time was 20.7 months in the adult group, 44.3 months in non-M-HLH patients, and 7.73 months in M-HLH patients (p= 0.011); univariate analysis showed that platelet count and serum albumin level affected prognosis; COX regression results in serum albumin level was an independent risk factor for prognosis.

CONCLUSION

The survival rate of non-M-HLH was significantly better than that of M-HLH; the proportion of NK cells had predictive value for the diagnosis of M-HLH; in the general population, non-M-HLH was more likely to have abnormal liver function than M-HLH: lower platelet count and serum albumin level were associated with poor prognosis, and the lower the platelet count and serum albumin level, the worse the prognosis: in addition, adults with lower serum albumin levels are also associated with poor prognosis.

Granulomas in bone marrow biopsies: clinicopathological significance and new perspectives

Bone marrow granulomas in trephine biopsies are a rare and usually incidental finding. Possible causes include infectious (especially tuberculous and rarer non-tuberculous mycobacteria, but also many other bacterial, viral, fungal and parasitic agents) and non-infectious causes (especially medications, autoimmune disease, sarcoidosis, haematological and non-haematological malignancy). Necrotising granulomas are generally suggestive of an infectious aetiology (tuberculosis being the most common), whereas fibrin ring granulomas are associated with Q-fever and Epstein Barr Virus, although exceptions are possible. Every case suspicious for infectious aetiology should undergo further analysis like special staining (Ziehl-Neelsen for acid-fast rods) or molecular studies. The histomorphology should always be clinically correlated. In cases in which no infectious cause can be identified, untargeted metagenomics may represent a valid diagnostic tool that may become standard in the near future for bone marrow diagnostics. In this review, we have analysed the published data from 1956 up to today, and we report aspects of epidemiology, aetiology, diagnostic algorithms, differential diagnosis and the role of metagenomics in bone marrow biopsies with granulomas.

A personalized approach to lymphoproliferations in patients with inborn errors of immunity

Biopsies from patients with inborn error of immunity (IEI) may pose a diagnostic challenge due to the abnormal anatomy of their lymphoid organs and the tendency for the development of lymphoproliferations in various organs, some of which may lead to the wrong impression of malignant lymphoma which may prompt aggressive unnecessary treatment. In this article we will review typical histologic findings in various IEI's described in the literature and discuss the appropriate approach to the diagnosis of lymphoproliferations in these patients by presenting illustrative cases.