@article {Benattia5252, author = {Amira Benattia and Emmanuelle Bugnet and Anouk Walter-Petrich and Gwena{\"e}l Lorillon and Sylvie Chevret and Abdellatif Tazi}, title = {The long-term outcome of adult pulmonary Langerhans cell histiocytosis: a national registry-based prospective cohort study}, volume = {56}, number = {suppl 64}, elocation-id = {5252}, year = {2020}, doi = {10.1183/13993003.congress-2020.5252}, publisher = {European Respiratory Society}, abstract = {Introduction: The long-term outcome of adult pulmonary Langerhans cell histiocytosis (PLCH) is unclear and an association with malignancy is strongly suspected.Aims and Objectives: Our objectives were to determine the overall survival of adult PLCH patients and the incidence of chronic respiratory failure (CRF), pulmonary hypertension (PH), and malignant disorders during follow-up.Methods: All PLCH patients newly diagnosed at adulthood at the French National Reference Centre for Histiocytoses between January 2004 and April 2018 and prospectively registered were included.Results: Two hundred and six patients (39 {\textpm} 13 years, 60\% females, 95\% current smokers) were followed for a median time of 5.1 years; IQR 3.2; 7.6. Twelve patients died during the study. The main cause of death was malignancy (42\%, mostly lung cancer). The estimated rates of survival at 5 and 10 years after PLCH diagnosis were 94\% (95\%CI 90; 98) and 93\% (95\%CI 89; 97), respectively. The 5 year cumulative incidence of CRF and PH was 6.3\% (95\%CI 3.4; 10.4) and 5.5\% (95\%CI 2.8; 9.5), respectively, with no further events after 5 years. Twenty-seven malignancies (11 lung cancer, 41\%) were observed in 23 patients, before (n=11), at the time (n=6), or after PLCH diagnosis (n=10, within a median time of 4.1 years; IQR 3.1; 5.0). The incidence of lung cancer was significantly higher than that expected using age- and sex-specific rates from the French population (SIR=16.7, 95\%CI 7.3; 38.1).Conclusions: Our findings provide important clues for the management of adult PLCH patients. Further studies are needed to identify risk factors for CRF and clarify the underlying mechanisms of cancer excess in PLCH.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 5252.This abstract was presented at the 2020 ERS International Congress, in session {\textquotedblleft}Respiratory viruses in the "pre COVID-19" era{\textquotedblright}.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/56/suppl_64/5252}, eprint = {https://erj.ersjournals.com/content}, journal = {European Respiratory Journal} }