Pediatric giant cell tumor of the tendon sheath of the craniocervical junction involving the occipital condyle.

INTRODUCTION: Giant cell tumor of the tendon sheath (GCTTS), also called pigmented villonodular synovitis, is a common lesion of the synovial membrane of the hand joint, but it uncommonly involves the axial skeleton, especially in pediatric populations. Furthermore, GCTTS originating from the occipital condyle has not been reported previously. CASE REPORT: A 15-year-old girl presented with a palpable neck mass for 1 year, and imaging studies revealed a less demarcated and heterogeneously enhanced mass in the suboccipital region. The tumor was originating from the occipital condyle that eroded the skull and atlas, and it was completely resected via a far lateral transcondylar approach followed by transarticular screw fixation. After the resection, we performed occipitocervical fusion to prevent spinal instability. The patient made an uneventful recovery after surgery. Recurrence has not been observed after 5 years of follow-up. DISCUSSION: We report this rare case and briefly review the general features and unusual locations of GCTTS with recommendations for treatment modalities.