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

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterized by extreme elevations in proinflammatory cytokine levels, may cause multiple organ failure. The adipose tissue depots in many sites include the visceral, subcutaneous, bone marrow. Up to now, adipose tissue was considered to be an endocrine organ, and these depots have distinctly different functions. Adipose tissue plays an important role in the development of inflammation, but the role of adipose tissue in HLH still needs to be investigated. The aim of the present study was to investigate the prognosis predicting value of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), clinical inflammatory cytokines in HLH.

Methods: We retrospectively collected 58 patients with newly diagnosed HLH from August 2016 to July 2019 in our nuclear department. All patients were followed up from 6 to 24 months. Firstly, a comprehensive comparison of the general data between the death group and the non-death group during follow-up period was made. Clinical lab indexes included white blood cell (WBC), hemoglobin (HGB), platelet (PLT), C-reactive protein (CRP), alanine aminotransferase (ALT), Aspartate aminotransferase (AST), triglyceride (TG), serum ferritin (SF), fibrinogen (FBG), erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), IL-1β, IL-2, IL-6, IL-10, IL-12, IL-18, GM-CSF, IFN-γ, and TNF-α. Secondly, the correlation between PET/CT semiquantitative metabolic parameters of VAT, SAT and inflammatory cytokines was performed. Thirdly, overall survival (OS) analysis was taken. Finally, the model was build based on risk factors to stratify patients. 3D slice based on 18F-FDG PET/CT was used to get SUV and volume of VAT and SAT.

Results: There was significant difference in WBC, PLT, FBG, IL-10, EBV-DNA, SCD25 between the death group and the non-death group. There was significant correlation between SAT coefficient variance (CV) and CRP, SAT SUVmean and TG, SUVmean and ESR. In univariate analysis with Cox regression analysis, VAT SUVmean, SAT Volume, SAT SUVmean, SAT CV, plasma EBV-DNA, WBC, PLT, FBG showed significance with OS. In multivariate Cox regression analysis, SAT Volume, SAT SUVmean, plasma EBV-DNA, were independent prognostic factors for OS.

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