Clinically relevant phenotypes in chronic rhinosinusitis.

Diagnosis and treatment of upper and lower airway conditions become increasingly important as phenotypes and endotypes are being described. There are well-described therapies to treat the different phenotypes of CRS, based upon the presumed underlying cause of the inflammatory process. Research continues to shed more light on different endotypes and phenotypes of airway inflammation, however, clinical differentiation of CRS can be applied in clinic practice with three simple phenotypes of CRS. Understanding these different phenotypes and their etiologies allows for further management beyond the 'maximum medical therapy and then surgery' approach that has often been used in the management of CRS.