Immunohistochemistry staining
To assess eosinophil degranulation, the second slide per sinonasal biopsy was immunostained for an eosinophil cytotoxic granule protein, eosinophil peroxidase (EPX), using primary anti-EPX antibodies (rabbit polyclonal anti-human EPX, 1:400 dilution, ab238506, Abcam, Cambridge, United Kingdom) (no retrieval) and the Ventana BenchMark Ultra automated staining system (Ventana Medical Systems, Inc., Tucson, United States). Immunoreactivity of EPX antibodies was enhanced with Ventana OptiView detection kit (Ventana Medical Systems, Inc., Tucson, United States). EPX-stained slides were compared with positive ovarian cancer controls. Slides were counter-stained with haematoxylin, and dehydrated at the end of the procedure. Positive cells and degranulation products stained brown.