Summary

Hyper-IgD syndrome (HIDS) is a rare, severe hereditary autoinflammatory disease characterised by periodic fevers, elevated serum IgD levels and a wide range of symptoms. Although a few randomised controlled trials have been performed in this disorder, there are no straightforward treatment protocols and none of the potential therapies are registered for this indication. We report a case of a young woman with severe HIDS who failed numerous therapies. Eventually, rational treatment with a monoclonal anti-interleukin 6 receptor antibody was initiated. This therapy resulted in an impressive clinical improvement and reduction in the number of hospital admissions per year. This case report underlines the difficulty of finding a suitable treatment for rare, severe inflammatory diseases. Furthermore, we show that treating patients with targeted therapies may result in clinical benefit for the patient, as well as simultaneously teach us more about the pathophysiology of these rare, relatively understudied diseases.