Rhinosinusitis and asthma: a very long engagement.

Upper and lower airways may be considered as a unique entity, interested by coexisting inflammatory processes that share common etiopathogenic mechanisms. Previous studies have strongly demonstrated a relationship between rhinosinusitis and asthma. This has led to the introduction of the concept of United Airways , which has also been included in the WHO document Allergic Rhinitis and its Impact on Asthma (ARIA); this concept has important consequences also on the treatment of these disorders. To better summarize the evident connection between upper and lower airway disease we decided to describe it as a multilayered construction, each level pointing out more deeply the relationship between these entities.