Almost all relevant studies identified for this review found that TSLP mRNA expression was increased in NP tissue of patients with CRSwNP compared with nasal mucosa tissue from healthy controls [36–39, 41] and in NP tissue versus control tissue (ethmoid sinus or uncinate process) in those with CRSwNP [43, 52] (though there were exceptions [47, 48]). Here, TSLP is linked to chronic rhinosinusitis with nasal polyps.