PET/CT Finds Occult Lesions in Children With Apparently Isolated Langerhans Cell Histiocytosis

A retrospective study in Pediatric Blood & Cancer assessed the added value of 18 F-FDG PET/CT in children with Langerhans cell histiocytosis (LCH) presenting as a clinically isolated lesion. The 44 children had undergone surgical resection with histopathological confirmation and received PET/CT before systemic therapy. Median age was 4.29 years, and 70.5% were male. Outcomes included additional lesion detection, disease reclassification and progression-free survival.

PET/CT identified additional lesions in 24 children (54.5%). Ten children (22.7%) were reclassified as having single-system multifocal disease and 14 (31.8%) as having multisystem disease. Four children (9.1%) had risk organ involvement. Imaging findings altered treatment strategy in 54.5% of patients. All five children who relapsed were in the group with additional lesions; the reported progression-free survival comparison had a p value of 0.044.

These findings suggest that clinically isolated LCH may conceal more extensive disease, with implications for staging and treatment selection. The authors recommend routine PET/CT in this setting. However, the small retrospective cohort does not establish that routine imaging improves clinical outcomes. Only the abstract was available, and follow-up duration and details of treatment changes were not provided.