POSTN and chronic rhinosinusitis with nasal polyps: Macrophage migration inhibitory factor and periostin were elevated in CRSwNP compared to CRSsNP.20,21 Chitinase-3-like protein 1 (YKL-40) and B-cell activating factor (BAFF) were found to distinguish patients with ECRSwNP and recurrent CRSwNP.14,22