Catamenial Pneumothorax as an Underrecognized Manifestation of Thoracic Endometriosis: A 25-Year Single-Center Experience

Objectives: Catamenial pneumothorax (CP) is a rare but clinically relevant cause of spontaneous pneumothorax (SP) in women and is associated with high recurrence rates. We hypothesized that CP is underrecognized in routine surgical practice due to an incomplete clinical assessment rather than an absence of characteristic intraoperative findings. Methods: We conducted a retrospective single-center analysis of all patients undergoing surgical treatment for pneumothorax between 2000 and 2025. Female patients with SP and no structural lung disease were identified and systematically evaluated for features suggestive of CP. Demographic, clinical, intraoperative, and outcome data were compared between patients with and without CP. Results: Among 4581 surgically treated pneumothoraces, 1253 (27.4%) occurred in women. Of these, 211 cases of SP without structural lung disease were analyzed. CP was identified in 15 cases among 14 patients (7.1%). Patients with CP were older at initial diagnosis (median 39 vs. 32 years; p = 0.0264) and exhibited higher recurrence rates (92.9% vs. 42.4%; p = 0.0003). A temporal association with menstruation was documented in 57.1% of CP cases, while in 35.7% no such assessment had been performed. Intraoperative findings suggestive of thoracic endometriosis were present in 85.7% of CP patients, whereas histological confirmation was achieved in only 14.3%. Conclusions: CP is likely underdiagnosed in surgical cohorts of women with SP. The principal diagnostic limitation appears to be incomplete history-taking rather than lack of intraoperative evidence. Given the high recurrence risk and limited efficacy of surgery alone, systematic assessment of menstrual association and interdisciplinary management are essential to optimize outcomes.