Catamenial pneumothorax: a challenging diagnosis

Catamenial pneumothorax is the most frequent manifestation of thoracic endometriosis. Diagnosis should be suspected if a spontaneous pneumothorax occurs within 72 hours from the onset of menstrual bleeding. Furthermore diagnosis can be supported by the macroscopic findings within the pleural cavity, generally represented by multiple nodules with color ranging from brown to violet and of variable dimension (from several micrometers to 1 cm); confirmation comes from histologic examination of the resected specimens (endometrial glands surrounded by a decidual-like stroma). Increased levels of CA 125 and CA 19–9 are useful clues. On the other hand, diagnosis of catamenial pneumothorax can be challenging in atypical cases presenting with none of the above mentioned features. We report a similar case in which diagnosis of catamenial pneumothorax was formulated, based on the ex juvantibus principle, only when, implementation of the specific medical treatment was able to prevent further recurrences of the disease.