Age-Stratified Imaging Selection in Langerhans Cell Histiocytosis: Towards a Clinical Decision Framework

Background/Introduction: Standardized staging imaging for Langerhans Cell Histiocytosis (LCH) is lacking. This study aims to identify patient and disease factors that influence imaging selection and propose a clinical decision algorithm that supports more deliberate, radiation- and cost-conscious use of imaging. Methods: A retrospective review of patients with biopsy-proven LCH, evaluated at a single institution, was conducted from 2001 to 2025. Age, sex, and presenting location at diagnosis were compared across imaging groups (Positron emission tomography/computed tomography [PET/CT], bone scintigraphy, and skeletal survey). Disease extent (unifocal, multifocal, multisystem) was summarized according to the imaging modality each patient received. Results: The cohort included 78 patients: 30 PET/CT, 11 bone scans, and 37 skeletal surveys. Median age differed significantly by modality: PET/CT 34 years (interquartile range [IQR] 8-56) vs. bone scan 13 years (3-37) vs. skeletal survey 7 years (2-14) (p < 0.001). Imaging selection varied significantly by anatomic location (p = 0.016): bone lesions were assessed with skeletal survey (52.8%), PET/CT (28.3%), and bone scan (18.9%). All pulmonary cases received PET/CT imaging. Six of the 78 patients had multisystem disease, and all six had been staged with PET/CT (Fisher's exact p = 0.006, PET/CT vs. skeletal survey; Bonferroni-adjusted p = 0.018). Conclusions: In addition to age, the initial presentation site influences the choice of imaging modality. Given the higher radiation burden and cost of PET/CT, further research is needed to determine whether this observed practice pattern translates to improved clinical outcomes.