Suppurative arthritis involving the synchondrosis of an os acromiale.

Os acromiale is an unfused epiphysis of the anterior part of the acromion occurring in approximately 8% of the population. Infection of this joint has not been previously described in the literature. We report such a case in a 59-year-old woman presenting with shoulder pain. A high index of clinical suspicion, with early imaging of the shoulder leading to prompt and definitive diagnosis, can lead to appropriate treatment and produce a favorable outcome.