Thoracic endometriosis syndrome: a rare cause of pneumothorax in young women

Clinical History

A 29-year-old female smoker came to our emergency department with right thoracic pain and dyspnoea. Auscultation revealed hypophonesis on right hemithorax.
The patient did not present fever, cough or other symptoms.

Imaging Findings

A chest radiography on posteroanterior view was performed (Fig. 1). A large pneumothorax with contralateral mediastinal displacement was observed. Pseudo-nodular extrapulmonar opacities adjacent to the right anterior diaphragm were also noted.
Two days later, after the placement of a thoracic tube, a complementary chest CT was ordered (Fig. 2 a-c). In this imaging technique a diminution of the right pneumothorax and the existence of extrapleural lesions attached to the right diaphragm were confirmed.
In order to improve the characterization of the extrapulmonary lesions, a thoracic MR was performed after the resolution of the pneumothorax (Fig. 3 a-d). Those extrapulmonary lesions were markedly hyperintense in T1 and fat-suppressed T1 sequences, with an intermediate-high T2 signal.
After the complete resolution of the pneumothorax, surgery was performed. Histological analysis confirmed the diagnosis.

Discussion

Endometriosis is defined as the presence of functional endometrial glands and stroma outside the uterine cavity [1]. The true prevalence of this disease is unknown. To make a definitive diagnosis biopsy, surgery or laparoscopy have to be performed. An estimated prevalence of 5-10% in all childbearing women has been described [2]. The most common location of endometriotic implants are the ovaries (76%) and anterior and posterior cul-de-sac (69%). However, these implants can arise in other atypical sites as gastrointestinal system, urinary system and thorax. When endometriotic implants extend to the thoracic cavity, they can produce a thoracic endometriosis syndrome (TES) [3]. TES can associate four different clinical entities: catamenial recurrent pneumothorax (CP), catamenial haemothorax, haemoptysis and pulmonary nodules.

CP is defined as spontaneous and recurrent pneumothorax occurring within 72 hours from the onset of menstruation. Although CP is the most common presentation of TES, it is a rare cause of pneumothorax accounting for less than 5% of cases of this disease in young women [4].

The most common locations of endometriotic implants in the thoracic cavity are the diaphragmatic surface and the visceral pleura [5], with the right thoracic cavity being involved most frequently. This fact supports the hypothesis of the retrograde menstruation and transdiaphragmatic leakage as a possible pathophysiology of TES.

Chest plain film is usually the imaging technique of choice when pneumothorax is suspected. The presence of pneumothorax and ipsilateral extrapleural opacities involving the diaphragm in a young woman within 72 hours from the onset of menstruation are the most common findings of CP. Chest CT can improve the detection of endometriotic implants due to its better spatial resolution. It can also give information about other possible differential diagnoses. MR can be helpful when CP is suspected. Typical endometriotic thoracic implants usually appear as well-defined lesions with high signal intensity on T1, T1 with fat saturation and T2 sequences [6].

The standard treatment of CP includes the pharmacologic inhibition of sex hormones with gonadotropin-releasing hormone analogues (GnRH). Since these drugs inhibit ovulation, patients who wish to conceive sometimes refuse to undergo hormone therapy. In some cases, this treatment could not be effective and the surgical removal of endometriotic implants using video-assisted thoracoscopic surgery could be an alternative choice. Nevertheless, a combination of surgical and hormonal therapy may be the preferred approach for treatment and prevention of recurrence of CP [5].

Differential Diagnosis List

Final Diagnosis

Thoracic endometriosis with catamenial pneumothorax

URL:	https://www.eurorad.org/case/13823
DOI:	10.1594/EURORAD/CASE.13823
ISSN:	1563-4086