Aetiology and differential diagnosis of rhinosinusitis The symptoms of rhinitis include nasal obstruction and mucoid or purulent rhinorrhoea

The lining of the nose and paranasal sinuses is continuous and it would be rare for inflammation to affect one without the other. In addition, the symptoms of sinusitis, particularly chronic sinusitis, and rhinitis overlap to a large extent and it is therefore convenient to consider the two together as rhinosinusitis. Similarly, the upper respiratory tract (nose and paranasal passages) and lower respiratory tract (tracheobronchial tree and alveoli) are closely related, not only in anatomy, but also in a number of physiological functions and responses to the environment. Chest disease is therefore frequently associated with rhinosinusitis and both the otolaryngologist and chest physician may see principles of aetiology, pathogenesis, investigation and management of diseases of one tract reflected in the other with instruction and advantage to each. The aim of this chapter is to consider the aetiology, differential diagnosis and medical treatment of rhinosinusitis with its associated chest diseases.