Rôle de la TEP/TDM au 18FDG dans la caractérisation et le suivi thérapeutique des histiocytoses

Abstract

ObjectivesBoth Langerhans’ cell histiocytosis (LCH) or non-LCH histiocytosis represent rare inflammatory diseases characterized by histiocytic infiltration. The objectives of this study were to evaluate 18F FDG PET/CT contribution to the metabolic characterization of histiocytoses and to assess the metabolic response to different immunomodulatory treatments. Patients and methodsOne hundred and twenty-seven initial and 457 follow-up 18F FDG PET/CT exams were compared with radiological (CT/MRI) findings. Metabolic responses to treatments (41 patients on IFN-α, 13 patients on vemurafenib and 7 patients on infliximab) were assessed by SUVmax (initial-final)/initial after measuring lesions with highest uptake. Results18F FDG PET/CT sensitivity and specificity varied with the organ and the histiocytosis subtype explored from 33 to 100% and from 60 to 100%. In comparison with CT/MRI and expressed in numbers of positive exams/number of total exams percentage, 18F FDG PET/CT identified more long bone (93% vs 86%) and sinus (50% vs 45%) lesions. 18F FDG PET/CT identified 17 metabolic responses (41%) on IFN-α (on 24 month median follow-up), one complete response and 8 (62%) partial responses on vemurafenib (12-month median follow-up), as well as a partial response on infliximab (on 15-month median follow-up). ConclusionsThe results of this large retrospective study suggest that whole-body 18F FDG PET/CT is informative at diagnosis for characterizing several localizations for each histiocytosis subtype and for the evaluation of the metabolic response to various immunomodulatory treatments.