Acromioclavicular Osteomyelitis: When Simple Cellulitis Is No Longer Simple

The objective of this case report is to highlight the importance of continued examination and evaluation to correctly diagnose and treat the rare condition of acromioclavicular osteomyelitis and associated septic arthritis. A 51-year-old diabetic male presented with right shoulder pain and overlying cellulitis without history of trauma, intravenous (IV) drug use, lacerations, prostheses or endocarditis later developed septic arthritis and osteomyelitis of the acromion and distal clavicle requiring operative management. Decision to re-image the joint using magnetic resonance imaging (MRI) with contrast after lack of symptomatic improvement was key to making the diagnosis.