Thoracic Endometriosis Syndrome (TES)

Thoracic Endometriosis Syndrome (TES) is a rare and often underdiagnosed form of extra-pelvic endometriosis in which endometrial-like tissue is found within the chest cavity. Unlike typical endometriosis, TES involves structures such as the lungs, pleura (the lining around the lungs), chest wall, or the upper surface of the diaphragm.

Symptoms of TES are frequently cyclical, meaning they worsen during or around menstruation. Common presentations include chest pain, shoulder pain, shortness of breath, or recurrent lung collapse during periods (known as catamenial pneumothorax). Less commonly, patients may experience coughing up blood or fluid around the lungs. Additionally, because these symptoms mimic more common pulmonary or cardiac conditions, many patients go years without an accurate diagnosis.

TES is most often right-sided and is thought to be related to diaphragmatic endometriosis. One prevailing theory suggests that endometriosis lesions on the diaphragm may allow tissue to migrate into the chest through microscopic defects. However, not all patients with thoracic disease have known diaphragmatic involvement, and the exact mechanisms remain an area of ongoing research.

Diagnosis is challenging. Standard imaging such as CT scans or MRIs may appear normal, especially when performed outside of menstruation. As a result, TES is frequently diagnosed only after repeated unexplained symptoms or during surgery. When surgery is required, treatment typically involves a multidisciplinary approach, combining advanced gynecologic surgery with thoracic surgical expertise to safely remove disease and reduce recurrence risk. Because TES can involve critical respiratory structures, appropriate recognition and referral to experienced specialists is essential for both safety and long-term outcomes.