The present studies doesn't show us, but the patient has a confirmed history of endometriosis with endometriotic lesions in thoracic cavity. This was her fourth pneumothorax episode during menstruation period, all of them on the right side. 

Endometriosis is a common and clinically important problem in women of childbearing age. It is classically defined as the presence of functional endometrial glands and stroma outside the uterine cavity and musculature.

This patient had a menstruation-related spontaneous pneumothorax, condition that is also termed as catamenial pneumothorax.