Synovial chondromatosis is a benign disorder characterized by the formation of multiple cartilaginous nodules in the synovium of large joints. Synovial chondromatosis of the spine is very rare; this is the first reported case in the skeletally immature pediatric spine. A 12-year-old female presented with a posteriolateral neck mass and discomfort. A two-stage surgical resection of the mass was performed. This case shows that synovial chondromatosis can occur in the immature pediatric spine. Synovial chondromatosis should be included in the differential diagnosis of a calcified paravertebral or lateral neck mass in children.