Epstein-Barr Virus–Associated Hemophagocytic Lymphohistiocytosis Mimicking Lymphoma on FDG PET/CT

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.

FDG-Avid But Pentixafor-Negative in EBV-Associated T-Cell Lymphoproliferative Disorders

ABSTRACT

An 18-year-old woman with intermittent fever, pancytopenia, abnormal liver function, and enlarged lymph nodes and hepatosplenomegaly was clinically suspected as hemophagocytic lymphohistiocytosis. 18F-FDG PET/CT showed increased metabolism in multiple lymph nodes, which were highly suggestive of lymphoma. No increased CXCR4 expression in lymph nodes was demonstrated on 68Ga-pentixafor PET/CT. Subsequent right neck lymph node biopsy pathology revealed EBV-associated lymphoproliferative disorders. Our case shows that 68Ga-pentixafor PET/CT may have potential value in differentiating EBV-associated lymphoproliferative disorders from lymphomas.

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.

Preclinical evaluation of [18F]FDG-PET as a biomarker of lymphoid tissue disease and inflammation in Zika virus infection

Purpose

Zika (ZIKV) is a viral inflammatory disease affecting adults, children, and developing fetuses. It is endemic to tropical and sub-tropical countries, resulting in half the global population at risk of infection. Despite this, there are no approved therapies or vaccines against ZIKV disease. Non-invasive imaging biomarkers are potentially valuable tools for studying viral pathogenesis, prognosticating host response to disease, and evaluating in vivo efficacy of experimental therapeutic interventions. In this study, we evaluated [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG)-positron emission tomography (PET) as an imaging biomarker of ZIKV disease in a mouse model and correlated metabolic tracer tissue uptake with real-time biochemical, virological, and inflammatory features of tissue infection.

Methods

[¹⁸F]FDG-PET/CT imaging was performed in an acute, lethal ZIKV mouse infection model, at increasing stages of disease severity. [¹⁸F]FDG-PET findings were corroborated with ex vivo wholemount-tissue autoradiography and tracer biodistribution studies. Tracer uptake was also correlated with in situ tissue disease status, including viral burden and inflammatory response. Immune profiling of the spleen by flow cytometry was performed to identify the immune cell subsets driving tissue pathology and enhancing tracer uptake in ZIKV disease.

Results

Foci of increased [¹⁸F]FDG uptake were consistently detected in lymphoid tissues—particularly the spleen—of ZIKV-infected animals. Splenic uptake increased with disease severity, and corroborated findings in tissue pathology. Increased splenic uptake also correlated with increased viral replication and elevated expression of pro-inflammatory cytokines within these tissues. ZIKV-infected spleens were characterized by increased infiltration of myeloid cells, as well as increased proliferation of both myeloid and lymphoid cells. The increased cell proliferation correlated with increased tracer uptake in the spleen. Our findings support the use of [¹⁸F]FDG as an imaging biomarker to detect and track ZIKV disease in real time and highlight the dependency of affected tissue on the nature of the viral infection.

Conclusion

[¹⁸F]FDG uptake in the spleen is a useful surrogate for interrogating in situ tissue viral burden and inflammation status in this ZIKV murine model.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05892-9.

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.

Multiple-Organ Involvement in Familial Hemophagocytic Lymphohistiocytosis Type 2 Shown on FDG PET/CT

ABSTRACT

FDG PET/CT in an 18-year-old man with known familial hemophagocytic lymphohistiocytosis (HLH) type 2 demonstrated abnormally in the brain, liver, and lymph nodes. Pathology showed no sign of lymphoproliferative disease. The patient underwent the chemotherapy of HLH. Six months after chemotherapy, a follow-up FDG PET/CT did not show any abnormal 18F-FDG activity, suggesting a complete response. The present case shows FDG PET/CT might not only be useful in staging the familial HLH but also able to evaluate the therapy response.

T-cell neoplasms in the spleen

Hematopoietic neoplasms involving the spleen are uncommon, but T cell neoplasms involving the spleen are extremely rare. The rarity of splenic involvement by T cell neoplasms has resulted in a limited body of literature describing their splenic characteristics. As a result, our purpose in this review article is to provide and summarize some of the characteristics seen by different T cell neoplasms that may involve the spleen.

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.

Is There Any Potential of FDG PET/CT in Monitoring Disease Activity in Familial Hemophagocytic Lymphohistiocytosis?

FDG PET/CT was performed in a 30-year-old woman to detect the source of fever of unknown origin. The images showed widespread abnormal activity, consistent with lymphoma. However, lymph node biopsy revealed only inflammation, and a diagnosis of familial hemophagocytic lymphohistiocytosis was eventually made after familial hemophagocytic lymphohistiocytosis-specific gene was detected. After proper therapy, a follow-up FDG PET/CT examination 2 months later showed resolution of most of the previously seen lesions.