Ventilation-perfusion scans in children treated for empyema.

omalizumab. Both patients have also been on long-acting b2 agonists and inhaled corticosteroids in standard doses throughout the time to control mild asthma symptoms (GINA I). In addition, they have required low dose prednisolone (5–10 mg) over the course of time to control blood eosinophilia, a hallmark of CSS exacerbation. We agree with Giavina-Bianchi et al that the longterm control of CSS requires immunosuppressant therapy and consider omalizumab as an effective add-on therapeutic agent. Because of the variability in the symptoms presented and the subspeciality of the referral centres who see these patients, a registry of patients with CSS is needed, based on clinical symptoms, regional background and therapeutic strategies. The underlying mechanisms as to how eosinophilia and cytokine signalling affects the course of the disease remains elusive and requires standardised treatment options and clarification of the molecular pathways to improve patient care.