[Rare lung diseases].

"Rare" diseases are a family of different disorders or conditions affecting fewer than 1/2000 in the general population. Among them, 150 involve respiratory system. To date, most reviews in literature focuses on the more important pulmonary lung diseases without taking in account the overall framework and diagnostic and therapeutic algorithms that allow a correct comprehensive approach to these disorders. The aim of our review is to describe a possible global approach to the management of these diseases trying to take a picture of the overall complexity of the field. We also want to highlight the role played by research on rare diseases pathogenesis in revealing, at least in part, mechanisms underlying many of "more common" disorders with the purpose to update the current state of knowledge.