**7. Characteristic findings of catamenial pneumothorax**

Characteristic lesions of the catamenial pneumothorax include single or multiple diaphragmatic spots, perforations, nodules, and visceral or parietal pleural spots and nodules. Pericardial nodules have also been reported in some cases.

These lesions have not been found in all patients with catamenial pneumothorax, but they have been revealed in some cases with noncatamenial pneumothorax. Detection of endometrial tissue is not mandatory in these lesions. On the other hand, endometrial tissue has usually been found in diaphragmatic and pleural nodules, but it is rarely detected at the edges of the diaphragmatic perforations [30].

Visceral and parietal pleural lesions are less frequently detected than diaphragmatic defects, spots, and nodules.
