eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2021-08-03 9 11 548 551 10.12691/ajmcr-9-11-8 AJMCR20219118 article Eric Taylor Mulkey 1 Gregory David Stewart gstewart@garnethealth.org 1 Mohammad Ismael 1 Cleveland Lewis 2 General Surgery, Garnet Health Medical Center, Middletown, NY, USA Thoracic Surgery, Garnet Health Medical Center, Middletown, NY, USA Endometriosis is a benign condition in which ectopic endometrial glands and stroma are present outside of the uterine cavity. It commonly affects the pelvic organs but can also spread throughout the entirety of the body, including the thoracic cavity. The ectopic presence of endometrial glands and stroma in lung or pleura can produce a range of clinical and radiological manifestations ¨C catamenial pneumothorax, catemenial hemothorax, catamenial hemoptysis, and pulmonary nodules ¨C collectively referred to as ¡°thoracic endometrial syndrome.¡± Thoracic endometriosis constitutes an uncommon cause of spontaneous pneumothorax in nonsmoking women of childbearing age. Symptoms are often non-specific and the diagnosis is often delayed. A thorough menstrual history and its temporal relationship to pneumothorax onset should be assessed in every women presenting with recurrent pneumothorax. Thoracic endometriosis syndrome is very manageable with the advancements of VATS and hormonal therapy, but we as clinicians should have this on our differential diagnosis when a young, reproductive-aged female presents with a spontaneous pneumothorax to expedite appropriate care. Here we present a case of a 44 year old female with recurrent spontaneous pneumothorax that was attributed to thoracic endometriosis that will hopefully educate providers to have a high clinical suspicion in patients to obtain an accurate diagnosis and initiate proper treatment. http://pubs.sciepub.com/ajmcr/9/11/8/ajmcr-9-11-8.pdf thoracic endometriosis syndrome recurrent spontaneous pneumothorax catamenial pneumothorax