Stepwise hormonal therapy for recurrent catamenial pneumothorax: GnRH agonist induction followed by individualized dienogest maintenance — a case series and literature review

Background Catamenial pneumothorax (CP) is the most common manifestation of thoracic endometriosis syndrome (TES). Recurrence remains a major challenge after surgical intervention, and evidence on long-term hormonal management is limited. This study evaluates whether dienogest (DNG) can serve as effective long-term maintenance therapy following gonadotropin-releasing hormone agonist (GnRH-a) induction in patients with recurrent CP. Methods This retrospective case series included four women aged 36–49 years with recurrent pneumothorax temporally associated with menstruation. We summarized clinical manifestations, thoracic surgical findings and pathological results (when available), gynecological evaluations, treatment regimens, recurrence outcomes, and adverse events. A literature review was conducted to identify previous reports on hormonal management of TES/CP. During long-term DNG treatment, periodic assessments included liver and renal function, coagulation profiles, breast ultrasonography, endometrial thickness, bone mineral density, and estradiol levels. Results All four patients showed a clear temporal association between pneumothorax and menstruation. One had histologically confirmed diaphragmatic endometriosis; the other three had only lung collapse with repeatedly negative thoracic imaging. After GnRH-a induction, all received individualized DNG maintenance (2–4 mg/day), initiated at 4 mg/day in severe or frequently recurrent cases or after low-dose failure and tapered to 2–3 mg/day once remission was achieved. After effective maintenance, no recurrence occurred during follow-up. Safety monitoring was unremarkable in three patients; one developed elevated liver enzymes after 21 months and normalized after switching back to GnRH-a. Literature review showed limited evidence on long-term DNG maintenance after GnRH-a induction, with no prior reports of individualized dose adjustment. Conclusions In this small case series, a structured regimen of GnRH-a induction followed by individualized DNG maintenance (2–4 mg/day; 4 mg/day initially or after escalation in severe/refractory cases, then tapered to 2–3 mg/day) appeared effective in preventing recurrent CP/TES, with no recurrence after effective maintenance was established. Long-term DNG was generally well tolerated, but safety conclusions are limited by the small sample size and one case of transient liver enzyme elevation; regular hepatic monitoring is required.