Pneumothorax in pulmonary langerhans cell histiocytosis (PLCH)

Background: Pneumothorax (PNO) is a salient complication of PLCH, which management is not standardized. The factors associated with PNO recurrence are poorly understood. Objectives: To determine PNO outcome after thoracic surgery and search for factors associated with the risk of recurrence. Methods: All PLCH patients ≥18 years with ≥1PNO between 11/2003 and 12/2015 of the database of the National Registry for histiocytoses and followed ≥6 months were retrospectively studied. Kaplan Meier method and univariate Cox models were used for statistical analyses. Results: Among the 43 patients included (39 smokers), 53% presented at least 1 PNO recurrence during a 49 months median time (53 additional episodes, 75% ipsilateral, all within 2 years). Thoracic surgery did not modify the risk of PNO recurrence, as compared to conservative treatment (p=0.96). However, the rate of recurrences was lower after thoracotomy (TCT), as compared to video-assisted thoracoscopy (VATS) (p=0.03). In the univariate analyses, lung function air trapping at diagnosis was associated with increased hazard of PNO recurrence (p=0.03). Patients whose LCH lesion harboured the BRAFV600E mutation had a lower rate of ipsilateral recurrences (p=0.019). When incorporating all ipsilateral recurrences, VATS was associated with increased hazard of subsequent recurrence (p=0.05). Conclusions: Surgery did not decrease the risk of PNO recurrence in PLCH. Thus, no particular treatment can be recommended for the first PNO in PLCH patients. In case of recurrence, TCT which appears more effective than VATS to prevent subsequent recurrence, should be privileged. The reduced risk of PNO recurrence associated with the presence of BRAFV600E mutation needs to be confirmed.