This Chinese study looked at the feasibility of periostin (usually found in bone and lung tissue) as a biomarker for chronic rhinosinusitis. They sampled ethmoid mucosa in 12 patients with chronic rhinosinusitis without nasal polyposis (CRSsNP) and 25 patients with chronic rhinosinusitis with nasal polyposis (CRSwNP). This was then compared to inferior turbinate biopsy of 15 patients with a deviation of their nasal septum but no CRSsNP or CRSwNP, acting as controls. Enzyme-linked immunosorbent assay (ELISA) and immunohistochemical staining (IHC) were used to detect the concentration of periostin in the nasal tissue specimens. They found that the serum concentration of periostin of patients with CRSsNP and CRSwNP was significantly higher than that from the patients with a deviated nasal septum (both P<0.01). Thus, the authors concluded that periostin is an inflammatory mediator involved in the local inflammation process of the nasal cavity and sinuses, and can provide a potential target for individualised therapy of CRS.