**1. Introduction**

Recurrent pneumothorax which is associated with menstruation is named as "catamenial pneumothorax" (CPX). It was first reported by Maurer et al. [1] and was presented to be a form of ectopic endometriosis and the term CPX was stated by Lillington et al. [2].

"Catamenial" is a name from Greek meaning "monthly." CPX is most commonly associated with endometriosis, but other etiological mechanisms of this disease exist [3–6].

In the literature, CPX is defined to be a recurrent pneumothorax occurring up to 24 h before or within 72 h after the onset of menstruation [4, 6], and on the other hand, not necessarily appearing every month [7]. Symptoms and signs of CPX are mostly unspecific so much clinical suspicion has to be maintained [8]. CPX is a rare entity; however, regarding literature, about one-third of all surgically treated cases of pneumothorax in women are diagnosed to be CPX [9–12].

Therefore, thoracic endometriosis should always be suspected in reproductiveage woman who suffer chest pain from spontaneous pneumothorax.

Thoracic endometriosis syndrome may be associated with other causes than pelvic endometriosis. In the first 24–48 h of menstruation, symptoms begin to appear and are usually seen on the right side of the chest. In 90% of the patients, chest pain is the most common symptom, and in one-third of the patients, shortness of breath is rarely seen, but hemoptysis is also added to the clinical picture [13]. In the light of these findings, the diagnosis of the disease is made clinically.

From 3 to 6% of spontaneous pneumothorax cases are catamenial pneumothorax, about one-third of all surgically treated cases of pneumothorax in affected women.

## *Pneumothorax*

The mean age of onset is reported to be 32–35 years [3, 4, 12, 14–17]. CPX may also develop as late as at 39 years of age [18, 19]. CPX occurs most often (85–95%) unilaterally, usually occurring on the right side of the chest, but there are cases on which pneumothorax also occurs on the left side or bilaterally [11, 15–21].
