PDGFRA and chronic rhinosinusitis: However, this agent proved efficacious in other diseases, namely in PDGFRA-negative hypereosinophilic syndrome [7] chronic obstructive pulmonary disease and peripheral eosinophilia [8], severe chronic rhinosinusitis with nasal polyps [9], chronic spontaneous urticaria [10,11], as well as in rare eosinophil mediated diseases (eosinophilic cystitis, fasciitis, pancreatitis and cholangitis, Kimura’s disease, eosinophilic cellulitis, eosinophilic granulomatosis with polyangiitis, eosinophilic pneumonia, and hyper-eosinophilic syndrome) [12,13,14,15].