Thoracic endometriosis is a rare condition in which endometrial tissue — tissue from the inner lining of the uterus (also called the endometrium) — becomes displaced and attaches to areas in or around the lungs. It can affect women of reproductive age (15 to 54 years old) who undergo menstruation.

Since endometrial tissue responds to sex hormones produced during the menstrual cycle, lung symptoms of this disease coincide with the monthly cycle.


The cause of thoracic endometriosis is not yet known. Patients who have undergone prior uterine surgeries can be prone to developing thoracic endometriosis due to the possibility of endometrial tissue being disseminated via the blood.


The most common symptom of thoracic endometriosis is chest pain right before or during menstruation. Other possible symptoms include shoulder pain and shortness of breath, although patients may also be asymptomatic. A woman with thoracic endometriosis may have periods that are painful (dysmenorrhoea).

In about 80 percent of cases, periods coincide with an accumulation of air in the chest cavity (the space between the lungs and the chest wall), which is also called catamenial pneumothorax or menstruation-related lung collapse. In about 14 percent of cases, blood may accumulate in the chest cavity during periods, a condition called catamenial hemothorax.

In some rare cases (about 5 percent), women have been reported to cough up blood during their menstrual cycles, having a condition known as catamenial hemoptysis. Endometriotic lung nodules, in very rare circumstances, can be seen during diagnosis.


Thoracic endometriosis is difficult to diagnose, although it has improved in recent years. A diagnosis is based on clinical history and examination, combined with chest radiograph, CT (computed tomography) scan, and magnetic resonance imaging (MRI).

Invasive methods might also be used to obtain tissue for a diagnosis. These include video-assisted thoracoscopy (VATS), bronchoscopy, or bronchoalveolar lavage.


Treatment options include surgical removal of endometrial lesions with laparoscopy, and pharmaceutical therapies such as danazol, contraceptive progesterones, gonadotropin-releasing hormone (GnRH) agonists, androgens, and non-steroidal anti-inflammatory drugs.


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