Catamenial pneumothorax

Abstract

Thoracic endometriosis syndrome is an under-recognised manifestation of endometriosis and includes catamenial pneumothorax, catamenial haemothorax, catamenial haemoptysis and pulmonary nodules. Catamenial pneumothorax presents as recurrent spontaneous pneumothorax with a temporal relationship to the onset of menses, affecting mostly the right lung. A 48-year-old woman presented with an eight-year history of right-sided catamenial pneumothorax, during which time she had three episodes of pneumothorax. Serial chest imaging revealed an enlarging mass overlying the right hemi-diaphragm. She was referred to our trust where she underwent video-assisted thoracoscopic surgery for right pleurectomy. Intraoperatively, defects were found in the right hemidiaphragm, through which parts of the liver had herniated. We describe the presenting features and management of catamenial pneumothorax.

Background

Thoracic endometriosis syndrome is an under-recognised systemic complication of endometriosis, defined as the presence of ectopic endometrial tissue within the thoracic cavity.¹ This syndrome encompasses several distinct clinical entities including catamenial pneumothorax, catamenial haemothorax, catamenial haemoptysis and pulmonary nodules.^1,2

Catamenial pneumothorax is the most common form of thoracic endometriosis syndrome (73%) and may account for 18–33% of spontaneous pneumothorax in women.² It presents as recurrent spontaneous pneumothorax in women of childbearing age, mostly affecting the right pleural cavity (92%) with a temporal relationship to the onset of menses (within 72 hours before or after the onset of menses, not necessarily every month).^1–3

Although catamenial pneumothorax is a clinical manifestation of thoracic endometriosis syndrome, histological evidence of thoracic endometrial deposits (ie thoracic endometriosis-related catamenial pneumothorax) was found in 52–87% of patients with catamenial pneumothorax who underwent surgery.⁴ For this reason, the diagnosis of catamenial pneumothorax is mainly made on clinical grounds, whereas the diagnosis of thoracic endometriosis-related catamenial pneumothorax is based on careful intraoperative inspection. Surgery plays a major role in both the diagnosis and management of catamenial pneumothorax, allowing for exploration and identification of associated lesions and defects in the thoracic cavity, including the diaphragm.

Case history

A 48-year-old woman presented with an eight-year history of recurrent pneumothorax affecting her right lung and a history of abdominopelvic endometriosis, proven intestinal endometrial deposits, haemochromatosis and infertility. She had experienced catamenial thoracic pain on almost every cycle from before her first pneumothorax presentation.

Symptoms at first presentation (aged 39) included haemoptysis, severe chest pain and dyspnoea, coinciding with menses. Chest radiograph (Figure 1) revealed a right-sided apical pneumothorax. Following a prolonged air leak she was referred for surgery, which she subsequently declined.

Figure 1 .

Chest x-ray showing right-sided pneumothorax – first episode of catamenial pneumothorax

She re-presented with a right pneumothorax following four years of stability while taking the combined oral contraceptive pill. The second presentation occurred following discontinuation the pill. Chest radiography demonstrated a right-sided pneumothorax and a nodule overlying the right hemidiaphragm (Figure 2). Computed tomography (CT) revealed multiple right-sided ‘pleural’ nodules overlying the diaphragm. Surgery was again declined by the patient.

Figure 2 .

Chest x-ray showing right pneumothorax and a laterally-based nodule overlying the right hemidiaphragm – second episode of catamenial pneumothorax

She re-presented four years later with a right-sided pneumothorax. On this occasion, she consented to surgical intervention. Interestingly, a chest x-ray demonstrated an enlarging nodule over the right hemidiaphragm (Figure 3). The nodule was further investigated with CT (Figure 4).

Figure 3 .

Chest x-rays showing a right pneumothorax and an enlarging nodule overlying the right hemithorax, with a pigtail drain in situ (right) – third episode of catamenial pneumothorax

Figure 4 .

Mass overlying the right hemidiaphragm: (left) axial view; (right) sagittal view

The patient underwent single-port video-assisted thoracoscopic surgery procedure where a 30° 10mm camera was inserted into the pleural cavity for initial inspection. This revealed herniation of the liver through a centrally located diaphragmatic defect, together with adhesion of the superior lobe to the parietal pleura. The diaphragm was inspected and three separate defects were found, following which a single line of defect was created via a longitudinal incision between the three. This incision was then repaired using multiples single stitches followed by plication to further cover and reinforce the repaired portion. Further to this procedure, a pleurectomy was undertaken and a 24F chest drain inserted. Pleural and diaphragmatic samples were sent for histological assessment but showed no evidence of endometrial deposits. Postoperative recovery was uncomplicated and the patient remained asymptomatic on clinical follow-up.

Discussion

Catamenial pneumothorax remains an underdiagnosed pathology⁵ (Rousset-Jablonski et al³ reported the incidence in surgical exploration was as high as 18–33%). Doctors should be cognisant of risk factors associated with catamenial pneumothorax which include previous pelvic surgery or uterine scraping, infertility, symptoms or diagnosis of pelvic endometriosis, mean age 34–37 years and catamenial pain.^1,2,4 Screening with these factors in mind may enhance diagnostic yield. Chest pain in catamenial pneumothorax is frequently bilateral (90.5%) whereas unrelated chest pain is rarely bilateral (3.6%).⁴ Symptoms of dysmenorrhoea and/or dyspareunia were found in 58.8% of patients with catamenial pneumothorax, and pelvic magnetic resonance imaging (MRI) or laparoscopic evidence of pelvic endometriosis was found in 67.6% of patients with catamenial pneumothorax.⁴

There are no specific radiological criteria for diagnosis, but findings on plain radiography include pneumothorax, haemothorax, haemopneumothorax, air-filled bubbles corresponding to diaphragmatic defects, nodular opacities overlying the right hemidiaphragm corresponding to partial intrathoracic liver herniation and/or pneumoperitoneum.¹ Other imaging modalities may reveal a hemidiaphragmatic mass corresponding to liver herniation, hypoattenuation related to endometrial implants (CT) and pleural masses secondary to endometriosis implants (MRI).

Although the exact mechanism of catamenial pneumothorax is unknown, many theories that have been formulated to explain the aetiopathogenesis and these include the following.^1,2

• •Physiological: bronchioalveolar blood vessel constriction, due to high levels of prostaglandin F2 during menses, leading to alveolar/subpleural bleb rupture.
• •Migrational/metastatic/microembolic: embolisation/metastasis or migration of endometrial cells from the uterine cavity to the thoracic cavity, with subsequent cyclical necrosis of those cells leading to pleural rupture.
• •Transgenital–transdiaphragmatic theory of air passage: in the absence of mucus plugging during menstruation, air passes from the genital tract through diaphragmatic defects, resulting in pneumothorax.

Conclusion

A number of risk factors associated with catamenial pneumothorax may aid doctors in establishing a diagnosis. The association between catamenial pneumothorax and recurrence mandates surgical intervention. Video-assisted thoracoscopic surgery is a useful modality catering for extensive inspection of the pleural cavity at the time of surgery.