Case Presentation: A 33-year-old female presented to the Emergency Department (ED) with one week of worsening shortness of breath and lightheadedness with exertion. She reported a history of iron deficiency anemia, endometriosis, and hypertension. She had received an injection of depot-medroxyprogesterone acetate approximately one week prior to presentation. On presentation, she was tachycardic, but vital signs were otherwise within normal limits, with no hypoxia on room air. However, chest x-ray and subsequent CT angiogram of chest revealed a large right-sided hydropneumothorax. A chest tube was placed in the ED by Interventional Radiology and patient was admitted to hospitalist-led medicine teaching service.Three weeks prior to presentation, the patient had been hospitalized at an outside hospital in an adjacent state for right-sided pneumothorax with pleural effusion. She underwent thoracoscopy that showed right-sided diaphragmatic holes and areas of endometrial implants. Pathology reports on diaphragmatic implant and right parietal pleural biopsies confirmed endometriosis involving soft tissues. Patient underwent right-sided partial pleurectomy, pleurodesis, and repair of diaphragmatic fenestrations. Over the course of the current hospital stay, the initial chest tube failed due to leak from securing suture lacerating chest tube. Despite repeat chest tube placement, pneumothorax continued to increase in size. The cardiovascular surgery service ultimately performed redo right thoracoscopy with right middle lobe web resection, partial pleurectomy, pleurodesis, and partial decortication. Patient was discharged on room air. She did present again to ED a couple weeks later with dyspnea, but no recurrent pneumothorax was present on chest x-ray. Her dyspnea was found to be due to COVID-19 infection, though she fortunately did not require hospitalization.

Discussion: We present a case of recurrent catamenial pneumothorax that was refractory to initial treatment. Catamenial pneumothorax is recurrent pneumothorax that is temporally related with menses, generally within 72 hours of bleeding onset. (1-4) While the exact incidence is unknown, literature suggests that among menstruating women, it accounts for 3-6% of spontaneous pneumothorax cases. (5) Catamenial pneumothorax normally presents as a right sided pneumothorax (in approximately 90% of cases) and is the most common presentation of thoracic endometriosis syndrome – which also includes catamenial hemothorax, hemoptysis, and pulmonary nodules. (3) Long term treatment is primarily focused on the prevention of recurrence, mainly with surgical intervention with diaphragmatic repair and pleurodesis as well as through hormonal suppression. Gonadotropin-releasing hormone (GnRH) agonist treatment with leuprolide is first-line, however our patient was unable to receive this therapy as cost was prohibitive. (6) Unfortunately, as seen with this patient, rate of recurrence of catamenial pneumothorax even with surgical and medical therapy is high. (5) While there are numerous theories proposed for the pathogenesis of catamenial pneumothorax, the exact etiology remains unknown.

Conclusions: Catamenial pneumothorax is a poorly understood condition that should be considered in the differential diagnosis for reproductive age women who present with spontaneous pneumothorax. Long term treatment usually involves both surgical and hormonal intervention; however, recurrence post treatment is high.

IMAGE 1: Chest X-Ray on presentation

IMAGE 2: Computed Tomography Angiogram of Chest on presentation