ABSTRACT
Several pathological conditions are closely associated with pediatric sinusitis. These comorbid conditions frequently exacerbate and may indeed precipitate pediatric sinusitis. Seven of the most common diseases associated with children who present with rhinosinusitis are discussed in detail in this chapter. A common pathophysiological outcome in many of these diseases is obstruction at the ostiomeatal complex (OMC). Edema and inflammation of the OMC, which can be seen with allergic rhinitis, asthma (especially allergic asthma), and extraesophageal reflux disease, can seal off sinus cavities, leading to stagnationofmucous and subsequentbacterial overgrowth. In patients with an immune dysfunction, this situation is exacerbated because of their inability to clear infections effectively. Edema and obstruction worsen as a result of the release of inflammatory mediators by mast cells and eosinophils to combat infection. With long-standing OMC obstruction, an anaerobic mileu develops in the sinus cavities, and chronic exposure to this environment damages the sinus mucosa and cilia, leading to ineffective mucociliary clearance. Patients with ciliary transport defects such as primary ciliary dyskinesia (PCD) and thick mucous secretions such as the ones seen in cystic fibrosis (CF) are further compromised because of their inherent defects in the clearance of the mucous blanket.
