Lung involvement in childhood Langerhans cell histiocytosis, A multi-institutional study from the french LCH study group

Objective: To assess clinical and radiological presentation of children with pulmonary Langerhans cell histiocytosis (PLCH) and their outcome. Methods: 166 children (1983 -2016) were included. Disease extension: risk organs (RO) were hematological involvement, liver and spleen. Patients were classified according to age: 10 years, group B. Results: 166 children (9,5%) had lung involvement of the LCH presentation. Median age at LCH diagnosis was 1.03 years in the group A (n=137) and 15,47 years in the group B (n=29). The group A had a more active disease, with 4 organs (median) more risk organs (RO) involved and poor prognosis. In contrast, the group B had less organs involved with less RO and 35% of them were active cigarette smokers. Radiologists reviewed 166 CT scans (from 54 patients) and semi-quantitative scoring was assigned for nodule (median score 1) and cysts (median score 0). During follow up, more patients had cysts, 54 patients (?%) had at least one bronchoalveolar lavage including 36% with a rate of CD1a>10%. Among the children with PCLH 153 (92 %) received chemotherapy (mainly Vinblastine + corticosteroids). After 1998, the 44 children (43.5 %) with poor response were treated with 2nd induction then with 2nd line chemotherapy with 2CDA + Cytarabine (ARACYTINEO) in the 30 patients with RO+. This new scheme of treatment improved the prognosis with 5-years survival rate increasing from 56 to 88% for RO+ patients with PCLH, while no change was observed in RO- patients. The rate of permanent adverse outcome remained high, especially if RO involves (46%) Conclusion: The expression of the disease varies from asymptomatic to chronic respiratory insufficiency, with no correlation with radiological score.