Polymyalgia rheumatica development in a patient under PI3K inhibitor therapy for chronic lymphocytic leukaemia.

We report a patient with chronic lymphocytic leukaemia (CLL) who was treated with idelalisib, a PI3Kδ inhibitor with rituximab. After 20 weeks of treatment, the patient developed classical signs and symptoms of polymyalgia rheumatica (PMR) in association with an elevated C reactive protein of 74 mg/L. After 2 weeks of prednisolone 15 mg daily symptoms had resolved and acute phase markers normalised. To our knowledge, this is the first report of PMR developing as a complication of PI3Kδ inhibitor treatment of CLL.