Incidental detection of Os acromiale mimicking a fracture on 18F-Fluoride PET-CT.

Os acromiale represents an unfused accessory centre of ossification of the acromion of scapula. It may cause shoulder impingement, rotator cuff tear or degenerative acromio-clavicular joint disease. A 38-year-old male with history of degenerative disc disease presented with persistent backache. MRI of the lumbar spine had earlier showed left paracentral disc protrusion of L5/S1 vertebrae impinging the left S1 nerve root for which the patient underwent fluoroscopic guided nerve root block. Due to persistent bilateral sciatica and worsening leg pain a decompression surgery was planned. A bone scan was requested to exclude other causes of pain prior to surgery for which the patient underwent 18F- Fluoride PET-CT examination. We report a case of incidental detection of Os acromiale mimicking fracture. As the management strategy for both is quite different this case highlights the importance of correct recognition of this identity for appropriate management.