Abstract
Chronic rhinosinusitis, historically, has been considered to be caused by upper airway anatomical abnormalities. However, today that concept has changed, for it is now recognized as an inflammatory disorder of the nasal and sinus mucosa. Acute rhinosinusitis is usually caused by a viral infection, whereas chronic rhinosinusitis is a persistent and heterogeneous inflammatory disorder with increased expression of type 1, 2, or 17 cytokines in the nasal and sinus mucosa, similar to that which occurs in asthma. Exacerbations are caused by aeroallergens in the allergic individual and irritants, pollutants, and viral/bacterial infections in all subjects. It may be categorized by phenotypes, examples of which include chronic rhinosinusitis with nasal polyps or chronic rhinosinusitis without nasal polyps. Defined endotypes are based on underlying pathophysiological mechanisms. Knowledge of chronic rhinosinusitis endotypes will optimize management by employing targeted medical therapies. Understanding that rhinosinusitis is a heterogeneous inflammatory disease has led to the identification of a variety of different predisposing conditions, new medical treatment options, and the concept that rhinosinusitis is primarily a medical problem.