A 27-year-old female with a right sacroiliac secondary chondrosarcoma arising from a sacroiliac osteochondroma. The tumor involved half of the sacrum, and a sagittal resection through the midline of the sacrum was required to obtain wide margins. She developed scoliosis and sitting imbalance and underwent a subsequent posterior spinal fusion and instrumentation. She remains free of disease 48 months after surgery.
