Chronic Nonbacterial Osteomyelitis/Chronic Recurrent Multifocal Osteomyelitis - A Case Report and Literature Review

Chronic non-bacterial osteomyelitis/chronic recurrent multifocal osteomyelitis (CNO/CRMO) is an autoinflammatory, sterile bone disorder that predominantly affects children but can also occur in adults. The nonspecific nature of its presentation, as well as relative lack of awareness of the condition, often results in significant diagnostic delay. In this article, we present the case of a female patient who began experiencing sternal pain at the age of 14, initially thought to be due to costochondritis but ultimately discovered to be secondary to CNO/CRMO. We demonstrate her long and tortuous diagnostic journey including key imaging and bone biopsy findings. We also report good clinical and radiographic response to tumour necrosis factor-α (TNF-α) inhibitors, despite having to switch from adalimumab (ADA) to etanercept (ETN) and then to methotrexate (MTX) due to side effects and anti-drug antibody production.