A girl presented with a left posterior triangle neck mass that had progressed for 3 years following a motor vehicle accident. On physical examination, the mass was firm, mobile, tender to palpation, and caused restricted range of motion. Ultrasound imaging of the soft tissue of the neck was obtained, which demonstrated a neck mass with dense acoustic shadowing (Figure 1A). Further evaluation with contrasted computed tomography (CT) imaging showed a 3.3×2.9×2.6-cm ossified lesion in the left posterior-lateral cervical soft tissue near the atlanto-axial junction. The lesion was well circumscribed and separate from the underlying bone (Figure 1B). The patient underwent excision of the mass without complication. The gross pathology specimen showed a firm, irregular, encapsulated mass.