Predictive value of metabolic parameters from PET/CT in adult multifocal Langerhans cell histiocytosis

PURPOSE: This study aims to explore the potential of 18F-FDG PET/CT-derived metabolic parameters in predicting the prognosis of adults with multifocal Langerhans cell histiocytosis (LCH). METHODS: This retrospective study included adult patients with pathologically confirmed multifocal LCH who underwent baseline 18F-FDG PET/CT scans at our institution and received appropriate treatment. The semi-quantitative PET/CT parameters evaluated included whole-body metabolic tumor volume (WBMTV), whole-body total lesion glycolysis (WBTLG), and maximum standardized uptake value (SUVmax). Receiver operating characteristic curve analysis was used to determine the optimal cut-off values for the metabolic parameters. Progression-free survival (PFS) analysis was performed for clinical features and PET/CT parameters using the log-rank test, Kaplan-Meier curves, and Cox proportional hazards models to identify prognostic factors for PFS. RESULTS: A total of 33 patients (22 male, 11 females; mean age 39 years, range 18–73 years) were included. During the follow-up period, 15 patients (45.5%) experienced disease progression or relapse. Univariate analysis revealed that age > 50 years, positive risk organs, SUVmax > 13, WBMTV > 36.79, and WBTLG > 277.22 were significantly associated with poor PFS (all p < 0.05). In multivariate analysis, SUVmax > 13 (HR = 4.521, 95% CI 1.137–17.968), WBMTV > 36.79 (HR = 13.278, 95% CI 1.415–124.569), and WBTLG > 277.22 (HR = 5.643, 95% CI 1.059–30.077) remained independent prognostic factors for PFS with statistical significance. CONCLUSION: Baseline 18F-FDG PET/CT-derived metabolic parameters may serve as promising imaging biomarkers for predicting the prognosis of adults with multifocal LCH.