18F-FDG PET/CT in follow-up evaluation in paediatric patients with Langerhans histiocytosis

Abstract

PurposeWe evaluated the impact of 18F-FDG PET/CT in identifying sites of active disease and assessing therapeutic follow up in a group of paediatric patients with Langerhans cell histiocytosis (LCH). MethodDuring 2007–2013, 13 18F-FDG PET/CT studies were performed for follow-up in 7 patients with a diagnosis of LCH (4 female, 3 male; 1–12 years-old). PET findings were analyzed and correlated with CT and MRI. Findings were also followed-up by these techniques. ResultsPET was negative in 4 patients (all diagnosed with bone lesions and one with additional pituitary involvement). CT findings showed residual morphological bone lesions in all patients, and an hypophysis MRI study showed no abnormal signal. PET remained negative at 10, 14, 25 and 28 months, and no new lesions on CT and MRI were detected. PET was positive in 3 patients (one with cervical lymphadenopathy and 2 with bone lesions, one also with pituitary involvement not identified by PET). CT findings showed pathological cervical lymphadenopathy (n=1), bone lesions (n=2) and also a pituitary MRI lesion (n=1). In a patient with cervical lymphadenopathy histology demonstrated LCH involvement. In the other 2 patients, PET remained positive with an increase of 18F-FDG bone uptake at 17 and 19 months. ConclusionIn our preliminar study, 18F-FDG PET is a useful imaging procedure, along with other diagnostic tools, for identifying active lesions.