ABSTRACT
Chronic rhinosinusitis (CRS) affects over 30 million persons in the United States each year and accounts for 11.6 million visits to physicians’ offices (1-3). It is increasingly apparent that CRS represents a variety of subtypes, each of which may differ in severity, associated comorbidities, optimal therapies, and prognosis. Past studies of CRS, which lump all subtypes together provide only limited insight with regard to comorbid associations and the efficacy of various targeted medical or surgical therapies. In 2004, a consensus was reached in defining CRS and recommending research parameters, which was drawn from representatives from the organized academies of general allergy, otolaryngology, otolaryngic allergy, and rhinology (4). A general grouping of CRS into forms with nasal polyps (NPs) and without NPs was proposed. A further subgrouping of CRS into either eosinophilic or noneosinophilic histopathologies was suggested. This strategy could potentially aid in identifying targeted therapies for each subtype of CRS, which might not have been appreciated in studies of a more heterogeneous collection of patients with CRS. The most refractory of the subgroups of CRS are those associated with eosinophilia. This chapter will review the epidemiologic evidence of eosinophilic CRS (ECRS) with regard to severity of disease and prognosis, as well as mechanisms that may account for more extensive disease in the eosinophilic conditions. Finally, potentially different and possibly overlapping mechanisms and associations that might serve as a further subgrouping of ECRS will be discussed, both pathophysiologically and in the context of potential logical targeted therapeutic interventions.
