Chronic non-bacterial osteomyelitis masquerading as fibrous dysplasia.

Chronic non-bacterial osteomyelitis is a rare auto-inflammatory bone disease seen predominantly in the paediatric population. We describe a unique case of a 30-year-old female who presented with right-sided jaw pain and intermittent swelling over the course of 6 years. She was initially treated with antibiotics for possible osteomyelitis, then temporarily diagnosed with fibrous dysplasia. She underwent extensive investigations consisting of an infectious workup, numerous imaging modalities, and three separate biopsies of her right jaw. She was ultimately diagnosed with chronic non-bacterial osteomyelitis based upon her history of recurrent episodes of painful swelling, response to non-steroidal anti-inflammatories, previously raised acute phase reactants, and magnetic resonance imaging findings. Unfortunately, she became refractory to non-steroidal anti-inflammatory therapy. Consequently, she was successfully treated with pamidronate, achieving clinical remission with improvement in her imaging findings. This case highlights the difficulty of diagnosis of chronic non-bacterial osteomyelitis and the need for increased awareness of the disease in the adult population. Additionally, the effective treatment with pamidronate supports the use of a bisphosphonate as an early intervention for adult-onset chronic non-bacterial osteomyelitis in patients who have failed non-steroidal anti-inflammatory therapy.