Background The optimal approach for management of spontaneous pneumothoraces (SPs) and the safety of air travel in patients with pulmonary Langerhans cell histiocytosis (PLCH) are not well established. Methods Patients with PLCH were recruited from the Rare Lung Diseases Clinic Network and the Histiocytosis Association, and surveyed about disease manifestations and safety of air travel. Results A total of 94 patients completed the survey. Median age at diagnosis of PLCH was 40 years (range: 15–67 years). Average interval between symptom onset and diagnosis was 2.9 years (range: −4 to 31 years). Twenty-two patients (23%) had at least one SP, of which 14 (64%) had at least one additional SP that showed either an ipsilateral recurrence (10 patients; 45%) or a contralateral recurrence (8 patients; 36%). Mean age at the time of first SP was 29 years. SP was the presenting manifestation that led to the diagnosis of PLCH in 19% of patients, typically after the second episode. Surgical pleurodesis reduced the recurrence rate of SP by half in comparison with conservative management (29% vs. 65%, p = 0.025). Two patients experienced an episode of SP during air travel, consistent with an air travel-related pneumothorax rate of 2.4% per patient and 0.27% per flight. Conclusions SP is a common manifestation of PLCH, can be seen in approximately one-fourth of the patients, and has a high recurrence risk. Surgical pleurodesis leads to a substantial reduction in the SP recurrence risk. The risk of an air travel-related SP in patients with PLCH is about 2–3 per thousand flights. Trial registry clinicaltrials.gov NCT03052101 .
