The role of 18F-FDG PET/CT in the management of patients with secondary haemophagocytic lymphohistiocytosis

Emerging Trends in Radionuclide Imaging of Infection and Inflammation in Pediatrics: Focus on FDG PET/CT and Immune Reactivity

The most common indication for ¹⁸F-FDG PET/CT is tumor imaging, which may be performed for initial diagnosis, staging, therapeutic response monitoring, surveillance, or suspected recurrence. In the routine practice of pediatric nuclear medicine, most infectious, inflammatory, and autoimmune processes that are detected on ¹⁸F-FDG PET/CT imaging - except for imaging in fever or inflammation of unknown origin - are coincidental and not the main indication for image acquisition. However, interpreting these "coincidental" findings is of utmost importance to avoid erroneously attributing these findings to a neoplastic process. We review the recent literature on fever of unknown origin as well as inflammation of unknown origin in pediatrics and then focus on the ¹⁸F FDG PET/CT imaging findings seen in two specific entities with increased immune reactivity: hemophagocytic lymphohistiocytosis syndrome and the immune-related adverse events associated with checkpoint inhibitors. We will subsequently close with two sections highlighting related topics and relevant references for further reading.

"A Dangerous Black Box:" Idiopathic Hemophagocytic Lymphohistiocytosis in Adult Patients-A Case Report and Review of the Literature

Hemophagocytic lymphohistiocytosis (HLH) is a rare potentially life-threatening condition characterized by aberrant inflammation that can be related to genetic or sporadic forms. In both forms, triggering factors may be involved. Early detection of the underlying cause is crucial for therapeutic decision, while early intervention might be associated with better outcomes. The largest descriptions in the literature on HLH refer to pediatric cases. Adolescents and adults may also be affected, but there is scarce evidence regarding their diagnosis and management. We describe here the case of a 68-year-old Swiss woman with HLH, in whom an extensive search for underlying causes was performed, but neither trigger nor pathogenic variant was found. An early intervention first with dexamethasone and later with cyclosporine was performed. The patient showed a favorable response and did not require further hospitalization; however, one year after diagnosis, it was not possible to suspend cyclosporine due to recurrence of laboratory inflammation signs by drug tapering. The occurrence of HLH idiopathic forms represents a challenge; failure to identify the underlying triggering cause generates uncertainty, endless diagnostic investigations, and consequently additional delays in the treatment. This manuscript addresses the difficulties on this issue.

Hemophagocytic Lymphohistiocytosis in Adults: A Retrospective Study in a Belgian Teaching Hospital

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, which can be primary (due to genetic mutation) or secondary to malignancy, infection and rheumatologic diseases. Data concerning Belgian patients with adult HLH are lacking.

Methods

This retrospective study was performed in a teaching hospital in Belgium. All cases of adult HLH, from December 2010 to April 2022, were reviewed. Patients with more than five HLH-2004 criteria and/or HScore >80% were included in the study. The objective of our study was to describe clinical and biological characteristics of patients with HLH and attempt to look for variables associated with mortality.

Results

Fifty-two patients were included in the final analysis. Mean age (SD) of patients was 48 (18) years old, and 29 patients were of male gender (56%). The underlying diseases associated with HLH were malignancy (M-HLH) in 22 patients, infection related HLH in 20 patients, rheumatologic disease related HLH in 7 patients, idiopathic in 2 patients and secondary to pregnancy in 1 patient. Overall mortality, mortality at 30 days and 90 days were 24/52 (46%), 13/52 (25%) and 4/52 (10%), respectively. In univariate analysis, malignancy, male sex, age and disseminated intravascular coagulation (DIC) were associated with mortality (p < 0.05). In multivariate analysis, only age was significantly associated with mortality (odds ratio, 1.053; 95% confidence interval, 1.016–1.092; p 0.005).

Conclusion

In our study, the most frequent triggers were malignancy and infectious agent followed by rheumatologic disease. Risk factors for mortality were age, male sex, malignancy and DIC, but only age remained significant in multivariate analysis. Treatment guidelines are mainly based on pediatric patients, and it is important for physician to describe adult patients’ outcome to better understand this disease and adapt treatment.

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

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

F-18 FDG PET/CT in NK/T-Cell Lymphoma that Progressed from Epstein-Barr Virus-Associated Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome involving an uncontrolled immune response with variable triggers. HLH is rare but highly fatal, even with proper treatment; therefore, early recognition and diagnosis are crucial for management. Although the role of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in HLH is poorly defined, it can provide valuable information on disease status and possible triggers. Herein, we report an F-18 FDG PET/CT study on a case of NK/T-cell lymphoma that progressed from Epstein-Barr virus-associated HLH.

Differential Diagnosis of Hemophagocytic Syndrome by 18F-FDG PET/CT: A Meta-Analysis

Hemophagocytic syndrome (HPS) is a rare disease in clinical practice, and there are often cases of delayed diagnosis. At present, researchers have applied 18F-FDG PET/CT in the differential diagnosis of HPS, but no consensus has been formed. Therefore, this study aims to systematically evaluate the application value of 18F-FDG PET/CT in the diagnosis of HPS patients. PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Wangfang database (Wangfang), and Chinese Biomedical Network (CBM) were searched to collect the relevant studies of 18F-FDG PET/CT in the diagnosis of HPS. Data from the articles were screened and extracted for meta-analysis using Stata16.0 software. A total of 10 retrospective studies, including 300 patients, were included in this meta-analysis. The meta-analysis results showed that the pooled sensitivity was 0.82 (95% CI: 0.67-0.95), specificity was 0.72 (95% CI: 0.51-0.86), positive likelihood ratio was 2.89 (95% CI: 1.46-5.75), positive likelihood ratio was 0.25 (95% CI: 0.12-0.54), diagnostic odds ratio was 2.89 (95% CI: 1.46-5.75), and AUC was 0.84 (95% CI: 0.81-0.87). The SUVmax in the liver, spleen, lymph nodes, and bone marrow of HPS patients was greater than 2.5, and the SUVmax in the spleen, lymph nodes, and bone marrow of malignant HPS patients was higher than that of benign HPS patients. The difference was statistically significant (P < 0.05). According to the existing literature evidence, 18F-FDG PET/CT is an effective method for diagnosing HPS.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Development and Validation of 18F-FDG PET/CT-Based Multivariable Clinical Prediction Models for the Identification of Malignancy-Associated Hemophagocytic Lymphohistiocytosis

Objective

¹⁸F-fluorodeoxyglucose (FDG) PET/CT is often used for detecting malignancy in patients with newly diagnosed hemophagocytic lymphohistiocytosis (HLH), with acceptable sensitivity but relatively low specificity. The aim of this study was to improve the diagnostic ability of ¹⁸F-FDG PET/CT in identifying malignancy in patients with HLH by combining ¹⁸F-FDG PET/CT and clinical parameters.

Materials and Methods

Ninety-seven patients (age ≥ 14 years) with secondary HLH were retrospectively reviewed and divided into the derivation (n = 71) and validation (n = 26) cohorts according to admission time. In the derivation cohort, 22 patients had malignancy-associated HLH (M-HLH) and 49 patients had non-malignancy-associated HLH (NM-HLH). Data on pretreatment ¹⁸F-FDG PET/CT and laboratory results were collected. The variables were analyzed using the Mann-Whitney U test or Pearson’s chi-square test, and a nomogram for predicting M-HLH was constructed using multivariable binary logistic regression. The predictors were also ranked using decision-tree analysis. The nomogram and decision tree were validated in the validation cohort (10 patients with M-HLH and 16 patients with NM-HLH).

Results

The ratio of the maximal standardized uptake value (SUVmax) of the lymph nodes to that of the mediastinum, the ratio of the SUVmax of bone lesions or bone marrow to that of the mediastinum, and age were selected for constructing the model. The nomogram showed good performance in predicting M-HLH in the validation cohort, with an area under the receiver operating characteristic curve of 0.875 (95% confidence interval, 0.686–0.971). At an appropriate cutoff value, the sensitivity and specificity for identifying M-HLH were 90% (9/10) and 68.8% (11/16), respectively. The decision tree integrating the same variables showed 70% (7/10) sensitivity and 93.8% (15/16) specificity for identifying M-HLH. In comparison, visual analysis of ¹⁸F-FDG PET/CT images demonstrated 100% (10/10) sensitivity and 12.5% (2/16) specificity.

Conclusion

¹⁸F-FDG PET/CT may be a practical technique for identifying M-HLH. The model constructed using ¹⁸F-FDG PET/CT features and age was able to detect malignancy with better accuracy than visual analysis of ¹⁸F-FDG PET/CT images.

Development and Validation of a Nomogram Based on 18F-FDG PET/CT Radiomics to Predict the Overall Survival in Adult Hemophagocytic Lymphohistiocytosis

Purpose: Hemophagocytic lymphohistiocytosis (HLH) is a rare and severe disease with a poor prognosis. We aimed to determine if ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET/CT-derived radiomic features alone or combination with clinical parameters could predict survival in adult HLH.

Methods: This study included 70 adults with HLH (training cohort, n = 50; validation cohort, n = 20) who underwent pretherapeutic ¹⁸F-FDG PET/CT scans between August 2016 and June 2020. Radiomic features were extracted from the liver and spleen on CT and PET images. For evaluation of 6-month survival, the features exhibiting p < 0.1 in the univariate analysis between non-survivors and survivors were selected. The least absolute shrinkage and selection operator (LASSO) regression analysis was used to develop a radiomics score (Rad-score). A nomogram was built by the multivariate regression analysis to visualize the predictive model for 3-month, 6-month, and 1-year survival, while the performance and usefulness of the model were evaluated by calibration curves, the receiver operating characteristic (ROC) curves, and decision curves.

Results: The Rad-score was able to predict 6-month survival in adult HLH, with area under the ROC curves (AUCs) of 0.927 (95% CI: 0.878–0.974) and 0.869 (95% CI: 0.697–1.000) in the training and validation cohorts, respectively. The radiomics nomogram combining the Rad-score with the clinical parameters resulted in better performance for predicting 6-month survival than the clinical model or the Rad-score alone. Moreover, the nomogram displayed superior discrimination, calibration, and clinical usefulness in both the cohorts.

Conclusion: The newly developed Rad-score is a powerful predictor for overall survival (OS) in adults with HLH. The nomogram has great potential for predicting 3-month, 6-month, and 1-year survival, which may timely guide personalized treatments for adult HLH.

Central Nervous System Involvement of Hemophagocytic Lymphohistiocytosis: When 18F-FDG PET/CT Solves a Complex Diagnostic Investigation

ABSTRACT

Hemophagocytic lymphohistiocytosis is rare life-threatening syndrome, hereditary or acquired, mainly affecting children. Hemophagocytic lymphohistiocytosis is an immune deficiency characterized by severe inflammation caused by uncontrolled proliferation of activated lymphocytes and macrophages. The usual biological and clinical data may associate polyadenopathy, hepatosplenomegaly, fever, multivisceral damages, and cytopenias with potential multiorgan dysfunction and death. We report the case of a 4-year-old girl, hospitalized for recurrent cerebellar symptoms (ataxia) associated later with fever and pancytopenia. 18F-FDG PET/CT revealed a node pathological uptake, which was biopsied and confirmed a diagnosis of hemophagocytic lymphohistiocytosis.

Clinical Management of Relapsed/Refractory Hemophagocytic Lymphohistiocytosis in Adult Patients: A Review of Current Strategies and Emerging Therapies

Introduction

Haemophagocytic lymphohistiocytosis (HLH) is a severe disorder with high mortality. The aim of this review is to update clinical management of relapsed/refractory HLH in adults, with a focus on current and new therapies.

Methods

We searched relevant articles in Embase and PUBMED with the MESH term “hemophagocytic lymphohistiocytosis; refractory; relapsing; adult.”

Results

One hundred eight papers were found; of these, 22 were retained for this review. The treatment of HLH in adult is based on the HLH-94 regimen. The response rate is lower than in pediatric patients, and 20–30% are refractory to this therapy. DEP regimen and allogenic hematopoietic stem cell transplantation (HSCT) are associated with complete response and partial response in 27% and 49.2%, respectively. However, many patients fail to achieve a stable condition before HSCT, and mortality is higher in them. New drugs have been developed, such as emapalumab, ruxolitinib, and alemtuzumab, and they may be used as bridges to the curative HSCT. They are relatively well tolerated and have few or mild side effects. With these agents, the rate of partial response ranges from 14.2% to 100%, while the rate of complete response is highly variable according to study and medication used. The number of patients who achieved HSCT ranged from 44.8% to 77%, with a survival rate of 55.9% to 100%. However, the populations in these studies are mainly composed of mixed-age patients (pediatric and adult patients), and studies including only adult patients are scarce.

Conclusion

Relapsed or refractory HLH in adult patients is associated with poor outcome, and consolidation with HSCT may be required in some cases. Mortality related to HSCT is mainly due to active HLH disease before HSCT and post HSCT complications. New drugs, such as empalumab, ruxolitinib, and alemtuzumab are interesting since these agents may be used as bridges to HSCT with increases in the numbers of patients proceeding to HSCT and survival rate.

Total metabolic lesion volume of lymph nodes measured by 18F-FDG PET/CT: a new predictor of macrophage activation syndrome in adult-onset Still's disease

Background

To investigate the potential utility of quantitative parameters obtained by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in the assessment of disease severity and the occurrence of macrophage activation syndrome (MAS) in adult-onset Still’s disease (AOSD).

Methods

Fifty-seven patients with AOSD who underwent pre-treatment ¹⁸F-FDG PET/CT were recruited in this study and compared with 60 age- and sex-matched healthy controls. Clinical features and laboratory data were recorded. The systemic score was assessed to determine the disease severity. The maximal standardized uptake value (SUV_max), metabolic lesion volume (MLV), and total lesion glycolysis (TLG) were used to evaluate the involved organs and tissues that abnormally accumulated ¹⁸F-FDG. Multivariate analysis was performed to identify the PET/CT-derived risk factors contributing to the AOSD-related MAS, and their diagnostic efficiency was evaluated.

Results

High ¹⁸F-FDG accumulation was observed in the bone marrow (SUV_max median, 5.10), spleen (SUV_max median, 3.70), and lymph nodes (LNs, SUV_max median, 5.55). The SUV_max of the bone marrow (rho = 0.376, p = 0.004), SUV_max of the spleen (rho = 0.450, p < 0.001), TLG_total of LNs (rho = 0.386, p = 0.017), and MLV_total of LNs (rho = 0.391, p = 0.015) were correlated with the systemic score. The SUV_max of the spleen (p = 0.017), TLG_total of LNs (p = 0.045), and MLV_total of LNs (p = 0.012) were higher in patients with MAS than in those without MAS. A MLV_total of LNs > 62.2 (OR 27.375, p = 0.042) was an independent predictive factor for MAS with a sensitivity of 80.0% and a specificity of 93.9%.

Conclusions

The glucose metabolic level of the spleen could be an effective and easy-to-use imaging indicator of disease severity, and MLV_total of LNs > 62.2 was a strong predictor of MAS occurrence in patients with AOSD.

Prognosis predicting value of semiquantitative parameters of visceral adipose tissue and subcutaneous adipose tissue of 18F-FDG PET/CT in newly diagnosed secondary hemophagocytic lymphohistiocytosis

PURPOSE

The purpose of this study was to investigate the prognosis predicting value of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of ¹⁸F-FDG PET/CT, and clinical inflammatory cytokines in newly diagnosed secondary hemophagocytic lymphohistiocytosis (SHLH).

METHODS

We retrospectively collected 58 patients with newly diagnosed SHLH from August 2016 to July 2019 in our hospital. All patients were followed up between 6 and 24 months. First, a comprehensive comparison of the general data between the death and the survival group was performed. Clinical lab indexes included were recorded and analyzed retrospectively. Second, the correlation between ¹⁸F-FDG PET/CT semiquantitative metabolic parameters of VAT, SAT and inflammatory cytokines was performed. 3D slicer software was used to get SUV and volume of VAT and SAT from ¹⁸F-FDG PET/CT. Third, overall survival (OS) analysis was performed. Finally, the prognosis predicting model was built based on risk factors to stratify SHLH patients.

RESULTS

There was significant difference in WBC, PLT, FBG, IL-10, PCR tests of EBV-DNA loads, SCD25 between the death group and the survival group. There was significant correlation between SAT coefficient variance (CV) and CRP, the mean standardized uptake value (SUVmean) of SAT (SAT SUVmean) and TG, SAT SUVmean and ESR. In univariate analysis with Cox regression analysis, SUVmean of VAT (VAT SUVmean), SAT Volume, SUVmean of SAT, CV of SAT (SAT HU CV), plasma EBV-DNA, WBC, PLT, FBG showed significance with OS. In multivariate Cox regression analysis, SAT Volume, SUVmean of SAT, plasma EBV-DNA, were independent prognostic factors for OS.

CONCLUSIONS

For newly diagnosed SHLH, SAT Volume, SUVmean of SAT, plasma EBV-DNA had significant relationship with poor prognosis. They were important independent predictors for overall survival for newly diagnosed SHLH.

Clinical and imaging features in adult patients with bone marrow haemophagocytosis with and without haemophagocytic lymphohistiocytosis: a single-institution experience

AIM

To evaluate clinical, laboratory, imaging findings, and outcomes of adult patients with bone marrow haemophagocytosis (BMH) who meet the diagnostic criteria for haemophagocytic lymphohistiocytosis (HLH) with those who do not meet the criteria.

MATERIALS AND METHODS

A pathology database search was performed from 2009 to 2019 to identify adult patients with BMH. Electronic medical records of 41 patients were reviewed to distinguish those who fulfil the HLH-2004 diagnostic guidelines, which identified 22 patients (11 men; mean age, 53.5 years) who met the criteria (HLH+) and 19 patients (13 men; mean age, 54.7 years) who did not meet the criteria (HLH-). Multi-modality imaging was reviewed to record imaging features. Clinical, laboratory, imaging findings, and outcomes were compared between the two groups using Fisher's exact test and Wilcoxon test.

RESULTS

Malignancy (non-Hodgkin's lymphoma) was the major trigger for both groups. 86% of HLH+ and 31% of HLH- patients presented with fever. Compared to the HLH- group, the HLH+ group exhibited higher serum ferritin, triglycerides, and lower fibrinogen levels (p<0.05). Alveolar opacities and hepatosplenomegaly were the most common imaging findings identified in both groups. Median overall survival of HLH+ and HLH- were 123.5 (interquartile range [IQR]: 40.7-681.7 days) and 189 days (IQR: 52-1680 days), respectively. Distribution of imaging features and overall survival did not differ between the groups.

CONCLUSION

Malignancy is the major trigger for BMH in both HLH+ and HLH- groups. HLH+ and HLH- groups have similar imaging manifestations or clinical outcomes. Therefore, presence of BMH alone is correlated with high morbidity and mortality.

Adult haemophagocytic lymphohistiocytosis: a Review

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder characterized by hyperimmune response. The mortality is high despite progress being made in the diagnosis and treatment of the disease.

AIM

This review aimed to update knowledge on adult HLH pathophysiology, identifiy the numerous causes, and help clinicians make early diagnosis and initiate treatment.

DESIGN AND METHODS

Using Embase, we searched relevant articles published from January 1, 2010 to October 31, 2019, with the MESH term « hemophagocytic lymphohistiocytosis; macrophagic activation syndrome, adult ».

RESULTS

The mean age at presentation is about 50 years, with a male predominance. The most frequent disease associations are haematological diseases, viral or bacterial infections, and autoimmune diseases. The pathophysiologic mechanism is probably the combination of inherited genetic mutations and extrinsic triggers. The mortality rate is 26.5% to 74.8%. H-score is more efficient than HLH-2004 criteria to identify HLH, with diagnostic sensitivity and specificity 90% and 79%, respectively.18F-FDG PET/CT is potentially useful for detecting underlying disease and the extent of secondary HLH. Disease-specific treatment should be given as soon as possible. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment. Monoclonal antibodies and JAK pathway inhibitors show promise of being effective.

CONCLUSION

In adult HLH, infectious diseases, autoimmune disease and malignancy should be suspected so that disease-specific treatment can be given promptly. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment, but new therapies show promise of being effective.

EBV-Associated T-Cell Lymphoproliferative Disorders Demonstrated on FDG PET/CT in a Patient With Hemophagocytic Lymphohistiocytosis

FDG PET/CT was performed in a 20-year-old woman to find the underlying cause of hemophagocytic lymphohistiocytosis. The images revealed hypermetabolic activity in multiple lymph nodes and in the spleen. Lymphoma was suspected. However, the pathology of bone marrow, lymph nodes, and the spleen demonstrated chronic active Epstein-Barr virus-associated T-cell lymphoproliferative disorders.

A prospective quality improvement initiative in adult hemophagocytic lymphohistiocytosis to improve testing and a framework to facilitate trigger identification and mitigate hemorrhage from retrospective analysis

Hemophagocytic lymphohistiocytosis (HLH) is a highly fatal, hyperinflammatory syndrome in adults triggered by an underlying illness in most cases. As such, suspicion of HLH dictates further investigation to identify the HLH trigger and determine treatment. HLH is clinically challenging due to diverse presentations and underlying triggers, provider unfamiliarity, and bleeding complications. Clinically, we observed diagnostic error from incorrect testing and cognitive biases (interleukin-2 confused with soluble interleukin-2 receptor and natural killer cell quantification confused with functional assays).This study reports our single institutional experience with adult HLH with the aim to reduce erroneous testing with a quality improvement (QI) project, and to facilitate trigger discovery and mitigate hemorrhage. Provider education on HLH testing was the prospective intervention, followed by mistaken test removal. HLH triggers and diagnostic utility were determined by retrospective chart review. Risk factors for hemorrhage were determined by multivariable analysis.Erroneous HLH testing was reduced from 74% to 24% of patients (P < .001) by the QI intervention. These changes were projected to save $11,700 yearly. The majority (64%) of patients evaluated for HLH were on non-hematology/oncology services, highlighting the need for vigilance in hematology consultation. Sixty-three patients met classic HLH-2004 criteria for HLH. Malignancy (38%), infection (27%), Epstein-Barr virus (EBV) (14%), or autoimmune disease (8%) triggered most HLH cases. HLH triggers were most commonly identified by serologic testing (27%) and bone marrow biopsy (19%). Biopsy of other affected organs based on PET-CT imaging after unsuccessful initial diagnostic measures was helpful, and focal fluorodeoxyglucose uptake was predictive of an underlying malignancy (likelihood ratio 8.3, P = .004). Major hemorrhage occurred in 41% of patients. On multivariable analysis the odds ratios (OR) for major hemorrhage were increased for patients with intensive care unit level care (OR 10.47, P = .005), and disseminated intravascular coagulation in the first week of admission (OR 10.53, P = .04).These data are incorporated into a framework to encourage early HLH recognition with the HScore, facilitate trigger identification, identify those at risk for hemorrhage, and minimize low-yield or erroneous testing.

Proliferation through activation: hemophagocytic lymphohistiocytosis in hematologic malignancy

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