Objective To investigate the clinical characteristics, treatment, and prognosis of children with systemic juvenile xanthogranuloma (JXG). Methods Children with JXG from January 2012 to December 2019 were retrospectively analyzed. Data relating to the clinical manifestations, laboratory values, treatment, and prognosis of the children were extracted from medical records. Patients underwent vindesine +prednisone as the first-line treatment and cytarabine + vindesine + dexamethasone +/- cladribine as the second-line treatment. Results Ten patients, including 8 males and 2 females, with an onset age of 1.95 (0.80-7.30) years, exhibited multi-system dysfunction. The median age of diagnosis was 2.45 (1.30-12.10) years. The most common location of extracutaneous lesions was the central nervous system (6 cases), followed by the lung (5 cases) and bone (4 cases). Nine patients underwent first-line chemotherapy, and 6 patients underwent second-line chemotherapy, including 5 patients with poorly controlled disease after first-line treatment. The median observation time was 20 (3-106) months. Nine patients survived, whereas one patient died of respiratory failure caused by pulmonary infection. By the end of follow-up, 7 patients were in an active disease (AD) state but better (AD-better), and 2 patients were in an AD-stable state. Three patients had permanent sequelae, mainly, central diabetes insipidus. The first-line treatment response rate was 40.0%, and the second-line treatment response rate was 66.7%. Conclusion The chemotherapy protocol for Langerhans cell histiocytosis (LCH) was effective for patients with systemic JXG, which also resulted in good outcomes. Central nervous system involvement did not impact overall survival, but serious permanent sequelae remained.

Background Langerhans cell histiocytosis (LCH) is a rare disease with a high frequency of the BRAFV600E mutation. We sought to investigate the effectiveness and safety of Dabrafenib in children with BRAFV600E-mutated LCH. Procedure A retrospective analysis was performed on 20 children with BRAFV600E -mutated LCH, who were treated with Dabrafenib and followed up from November 1, 2016, to June 1, 2020. Results The median age at which the patients started taking Dabrafenib was 2.3 (0.6-6.5) years old . All patients were initially treated with chemotherapy and then changed to targeted therapy due to poor response or intolerance to chemotherapy. The overall objective response rate and disease control rate were 65% and 75%, respectively. Among the 15 patients who had positive circulating cell-free BRAFV600E (cfBRAFV600E) mutation before Dabrafenib treatment, decreased cfBRAFV600E level was observed at the end of treatment (P=0.029). In 9 of 15 (60%) patients, cfBRAFV600E level became negative within a median time of 3.0 months (1.0-9.0 months). All patients survived, and a half of them suffered a relapse or progression after Dabrafenib treatment. Grade 2 or 3 adverse effects occurred in 5 patients. Relief of adverse effects was obtained after symptomatic treatment, reduction of dosage or withdrawal. Conclusions Some children with BRAFV600E-mutated LCH may benifit from monotherapy of Dabrafenib, especially high-risk patients with concomitant HLH and intolerance to chemotherapy. The safety of Dabrafenib is notable. A prospective study with a larger sample size are required to determine the optimal dosage and duration of Dabrafenib.