Role of 18F-FDG PET/CT in management of Langerhans Cell Histiocytosis

1689 Objectives: To analyze the clinical characteristics and 18F-FDG PET/CT manifestations of patients with Langerhans cell histiocytosis (LCH), and to explore the value of 18F-FDG PET/CT in the diagnosis, classification, treatment response evaluation and lesion progression of LCH. Methods: The clinical and imaging data of 14 patients (9 males and 5 females, with an average age of 43.07±11.72 years) who underwent PET/CT examination and were confirmed by pathology in our hospital from August 2013 to July 2019 were retrospectively analyzed, especially the 18F-FDG PET/CT manifestations. Results: The main clinical manifestations of 14 patients included bone pain, diabetes insipidus, cough, fatigue, local mass, etc. A total of 77 bone lesions were found in 18F-FDG PET/CT, mainly distributed in the skull (27 cases), ilium (17 cases), vertebral body and adnexa (13 cases), etc. The uptake of 18F-FDG was increased in different degrees, SUVmax was 7.77±3.97, MTV was 2.76±3.21, and TLG was 13.99±18.81. Pulmonary nodules and cystic bright shadows were found in 4 patients, slight uptake of 18F-FDG was increased, and SUVmax was all less than 2.34. Six patients presented multiple enlarged lymph nodes with increased uptake of 18F-FDG, and 65 lesions were mainly distributed in mediastinum, axilla, inguinal and pelvic wall. SUVmax was 4.14±2.64, MTV was 1.47±1.13, and TLG was 3.77±3.55. In addition, there were 1 patient with multiple intrahepatic nodules and 1 patient with thyroid mass, and the uptake of 18F-FDG was significantly increased. In addition, three patients after treatment for 18F-FDG PET/CT check, 1 case of swollen lymph nodes, 1 case of patients characterized by dissolving osseous bone destruction focal density increased, 1 cases of lesions and swollen lymph nodes shrinking, the most (92.5%) lesions 18F-FDG uptake reduced after treatment (SUV average was 5.89±2.47 at lesions before treatment, after treatment was 2.35±2.78).Another patient 1 was reexamined after 1 year without treatment. The lesion was obviously enlarged and the glucose metabolism was obviously increased. Conclusions: 18F-FDG PET/CT can be used for the diagnosis of bone lesion, lymph node lesion, affected range, degree and activity of different organs and tissues of LCH, and has a good clinical value for the classification and diagnosis of LCH. Meanwhile, 18F-FDG PET/CT can simultaneously evaluate the therapeutic effect and lesion progression of LCH. Key words: LCH; PET; FDG