Pathophysiology of Chronic Rhinosinusitis with Nasal Polyps

Chronic rhinosinusitis (CRS) is defined the following way in the 2012 EPOS guidelines: nasal and paranasal sinus inflammation lasting a minimum of 12 weeks, plus at least two of the following features: blocked nose, rhinorrhoea, pain or pressure sensation over the face, hyposmia or anosmia. According to this guideline, at a minimum, the nose should be obstructed or there must be nasal drip anteriorly or posteriorly to qualify for the diagnosis. This clinical diagnosis can then be confirmed objectively through CT scanning of the sinuses or nasal endoscopy, which also permits characterisation as chronic rhinosinusitis with or without nasal polyp formation (CRSsNP and CRSwNP, respectively). Polyps characteristically contain elevated levels of IL-5 and IL-13, produced by T-helper 2 cells, as well as histamine. Through the endoscope, polyps take on a translucent, glistening appearance, with a colour between yellowish-grey and white, and are seen to contain abundant inflammatory debris of a gelatinous consistency. They arise from the mucosal linings of the nasal sinuses or the nose itself. They are particularly frequent at the ostia of the sinuses. Due to being poorly vascularised, polyps have a greyish-white appearance. It is fairly uncommon to find polyp formation confined unilaterally, despite the occurrence of a sole polyp on occasion at the middle meatus or the posterior recess of the sphenoethmoid. Polyps which form unilaterally may exhibit a difference in appearance and are a suspicious feature for inverting papilloma, fungal infection or a neoplasm. Combining sinusal CT with MRI is often beneficial diagnostically. A confirmation of unilaterality through imaging should make the clinician evaluate other possible diagnoses. Pathophysiology of chronic rhinosinusitis with nasal polyps is presented. © Springer Nature Switzerland AG 2020.