Recurrent pneumothorax: the unexpected encounters

We read with interest the article by Papagiannis et al. providing an introduction and categorization of the aetiology of pneumothorax into broadly primary and secondary (1). The aetiology of recurrent pneumothorax may deserve a special mention, although in the young population it is most likely due to primary cause from apical blebs or bullae, one should have a low threshold to perform further investigations to seek potential alternative pathological explanations for the recurrent spontaneous pneumothorax. We would like to share our experience of some rarer causes for recurrent pneumothorax.