ABSTRACT
There are a variety of systemic diseases including vasculitic, granulomatous, and autoimmune diseases that, among other body parts, also affect the lower and upper airways, including nasal mucosa and paranasal sinuses. The nasal symptoms and signs of these diseases are usually not specific and may mimic an allergic or nonallergic rhinitis, or even a chronic rhinosinusitis. When appropriate tests such as allergic skin-prick tests or blood tests give negative results, a systemic disease involving the nasal or paranasal layers should be suspected. In the present chapter, the authors have tried to provide a short but useful overview of the main vasculitic, granulomatous, and autoimmune systemic disorders to be included in the differential diagnosis of nonallergic rhinitis and chronic rhinosinusitis.
