Definition:

Eosinophilic chronic rhinosinusitis (ECRS) is an inflammatory pathological condition of the nose and paranasal sinuses. Chronic rhinosinusitis (CRS) is a common disease worldwide, and CRS may be divided into ECRS and non-ECRS subtypes based on the presence of tissue eosinophilic infiltration or not. There are significant geographic and ethnic differences in the tissue eosinophilic infiltration, which is predominant in Western white patients and less common in East Asians, despite an increasing tendency for its prevalence in East Asia countries. ECRS commonly demonstrates more severe symptoms, polyp diseases with a higher incidence of bilateral polyps and sinonasal diseases on computed tomography, and the increase in blood eosinophils. Patients with ECRS exhibit clinical characteristics that include long term nasal congestion, mucus production, olfactory disturbances, bilateral nasal polyposis, and intermittent acute exacerbation of secondary bacterial infections. Since there is no approved medication to treat patients with ECRS with nasal polyps completely, surgery is often needed to clear the sinonasal passage, and repeated endoscopic sinus surgery (ESS) is often required. The effectiveness of low-dose, long-term erythromycin treatment (macrolide therapy) was reported for the treatment of CRS in Japan.