Catamenial pneumothorax and endometriosis: Report of a rare case

Catamenial pneumothorax (CP) was first described by Lillington et al. in 1972 [1]. It is considered as a rare condition and subtype of pneumothorax which is related to menstruation and endometriosis. This condition is usually misdiagnosed and characterized by the recurrent accumulation of air within the pleural cavity without concomitant respiratory diseases. The typical clinical manifestation is spontaneous pneumothorax, or this condition may also be asymptomatic. It happens in reproductive age women, usually within 72 hours of onset of menstruation [2]. Thoracic endometriosis, right side involvement, and distinctive pleural lesions (multiple diaphragmatic fenestrations, brown nodules on the diaphragm) are characteristic of this condition [2].

A 35-year-old woman, premenopausal, para 1 presented to the emergency department with sudden onset of shortness of breath and chest pain. This episode coincided with the first three days of her menstruation. She alluded to prior episodes of left shoulder pain and chest pain occurring during her menstruation. She also had a past history of a spontaneous right hydropneumothorax four weeks prior to presentation for which she had a chest tube insertion drainage in the emergency room as well as care in the intensive care unit. Additionally, there was also a history of a small left apical pneumothorax two years prior to presentation which required no intervention. A history of pelvic and peritoneal endometriosis, infertility and 2 laparoscopies of the pelvis was also noted. However, there was no history of chronic lung disease, recent surgical procedures, or trauma. There was no additional pertinent personal or family medical history.

Clinical examination revealed tachypnea, mediastinal shift from right to left and reduced breath sounds. The laboratory results were within erence range. Chest X-ray showed right-sided moderate to large hydropneumothorax (Figure 1). A chest CT performed, revealed bilateral pleural nodularity in keeping with pleural-based endometriosis deposits and right basal atelectatic changes also noted (Figure 2). A transvaginal ultrasound (US) showed severe endometriosis including extra-pelvic endometriosis of the abdominal wall. Specifically, rectal and severe posterior compartment endometriosis was noted. There was also severe obliteration of the rectouterine pouch and benign cystic lesion in the left adnexa. There was free blood in the right adnexa likely due to a retrograde menstruation. In spite of several chest drains, her lung did not expand and she continued to have persistent air leaks. She underwent a flexible video-assisted bronchoscopy, right video-assisted thoracoscopic surgery (VATS). Intra-operatively, there were adhesions seen between the right lung and the chest wall and an area of abnormality on the lateral wall of the right upper lobe between the apical and posterior segments. The pleura was also abnormal in this area. A wedge resection of the right upper lobe of the lung was performed and the specimen was sent for pathology analysis.

Grossly, the specimen comprised a wedge resection of the upper lobe of the right lung, which measured 7.7 cm × 1.5 cm × 1.2 cm and weighed 4.9 grams. The pleura of the lung was mottled brown-gray with adhesions. The lung parenchyma was tan and appeared relatively unremarkable. Microscopic examination showed endometrial glands and stroma surrounded by hemorrhage as well as fibrosis of the pleura (Figure 3). There was also acute and chronic inflammation in addition to subpleural chronic inflammation (Figure 4). Mild emphysematous change of lung parenchyma was also noted. Immunohistochemical stains performed confirmed the endometrial glands and stroma to be estrogen receptor (ER) positive (Figure 5) and the endometrial stroma to be CD10 positive (Figure 6).

The postoperative course was uneventful, and the patient was discharged four days after surgery. She was subsequently placed on Leuprolide injections every three months and Norlutate as an add-back hormone for a period of one year. She has not had any recurrence of shortness of breath or chest pain in the last two years following her surgery. She remains quite stable from a thoracic standpoint. However, she continues to experience pelvic and abdominal pain while on medical management and is scheduled to have a laparoscopic resection of bowel endometriosis.

Risk factors associated with catamenial pneumothorax include previous pelvic surgery, uterine scraping, infertility, mean age of 32–35 years, and symptoms of pelvic endometriosis [2]. Screening with these factors may enhance the diagnostic yield [3]. Our index case similarly was 34 years and had a history of infertility and had undergone 2 laparoscopic pelvic procedures prior to the presentation of catamenial pneumothorax. The typical clinical manifestation of catamenial pneumothorax involves spontaneous pneumothorax preceding or in synchrony with menses, usually presenting with pain, shortness of breath and cough. Scapular and or thoracic pain preceding or in synchrony with menses, history of previous episode(s) of spontaneous pneumothorax with or without previous surgical interventions is highly suspicious [4],[5]. Most of the cases of catamenial pneumothorax are right-sided, similar to this case but some can be left or bilateral. The pathogenesis of this disease entity is likely multifactorial. Several theories hypothesize the causation of this condition including the retrograde menstruation theory, coelomic metaplasia theory, lymphatic and hematogenous dissemination theory, and the prostaglandin theory [6].

A detailed history and physical examination are important prerequisites to the diagnostic work-up. The work-up is composed of imaging modalities such as chest X-ray (CXR), computed tomography (CT), and magnetic resonance imaging (MRI) [7]. Chest X-ray and CT chest are the most sensitive in detecting pneumothorax. Radiological findings include pneumomediastinum, pneumoperitoneum, ground-glass opacities, bronchial-wall thickening, thin-walled cavities within the lung parenchyma, or bullous formation [8],[9]. Chest X-ray in our case revealed a right-sided moderate to large hydropneumothorax and a chest CT revealed bilateral pleural nodularity in keeping with pleural-based endometriosis deposits and right basal atelectatic changes. Interventional procedures like bronchoscopy, video laparoscopy, and video-assisted thoracic surgery are also included in the work-up regimen.

The gold standard of surgical intervention is video-assisted thoracic surgery (VATS) [10]. Depending on the variability of the case presentation, alternative procedures may also be performed including thoracotomy, and pleurodesis (chemically or surgically). Most commonly reported intraoperative findings included diaphragmatic lesions (38.8%), endometriosis of the visceral pleura (29.6%), discrete lesions such as bullae, blebs, or scarring (23.1%) and no findings (8.5%) [3]. In this case, there were adhesions seen between the right lung and lateral chest wall with some pleural abnormality; however, no overt diaphragmatic lesions or endometriosis of the lung pleura were observed intraoperatively.

Thoracic endometriosis has been considered as histologically “proven” after identification of endometrial stroma and glands in the thoracic lesions and as “probable” after identification of stroma only [4],[5],[11],[12],[13]. In our case, histologic examination showed endometrial glands and stroma surrounded by hemorrhage as well as fibrosis of the pleura; which was confirmed by immunohistochemical stains.

As far as treatment is concerned, VATS in conjunction with hormonal therapy for at least six months has been found to show an improvement in prognosis and a decrease in the possibility of a recurrence of catamenial pneumothorax [14]. Medical management includes hormonal therapy in the form of gonadotropin releasing hormones and aromatase inhibitors perably for a period of 6–12 months. Similarly, our index case underwent VATS and was treated with Leuprolide for one-year post-surgery with no recurrence of symptoms of thoracic endometriosis.

There should be a high index of suspicion of catamenial pneumothorax in women of reproductive age who present with pneumothorax during or around the perimenstrual period. Adequate sampling of lung wedge resections and caul microscopic examination, followed by confirmation with immunohistochemistry play important roles in the diagnosis of this rare condition.