Clinical features of recurrent spontaneous pneumomediastinum.

Background: Spontaneous pneumomediastinum recurrence is rare, and its clinical presentation is unclear. We investigated the clinical features of and predisposing factors for spontaneous pneumomediastinum recurrence. Methods: We retrospectively investigated 30 consecutive patients treated for new-onset spontaneous pneumomediastinum at Shinshu Ueda Medical Center between 2012 and 2021. We evaluated the patient background characteristics, trigger activity, radiological findings, and clinical course of spontaneous pneumomediastinum, including those of recurrent cases. Predisposing factors for spontaneous pneumomediastinum recurrence were evaluated by comparing patients with and without recurrence. Results: Most patients were male (87%). The median age of the patients was 16 years (range, 12-26 years). Among the 30 patients, five experienced at least one recurrence of spontaneous pneumomediastinum. All recurrences occurred within 1 year after new-onset spontaneous pneumomediastinum. Clinical presentations associated with spontaneous pneumomediastinum recurrence, including vital signs, laboratory data, length of hospital stay, and radiological extent of spontaneous pneumomediastinum, were similar to or less aggressive than those associated with new-onset spontaneous pneumomediastinum. Patients with recurrence were more likely to have a medical history of preexisting lung diseases, such as asthma, than those without recurrence (60% vs. 8%; P=0.022). Only one of five patients with recurrence had trigger activity at spontaneous pneumomediastinum onset (20%); however, 60% of patients without recurrence had trigger activity (P=0.15). Conclusions: Spontaneous pneumomediastinum recurrence may have a similar or less aggressive clinical presentation than new-onset spontaneous pneumomediastinum. The presence of preexisting lung diseases may increase the risk of spontaneous pneumomediastinum recurrence.