Preschooler with back pain, limited right hip motion, and a limp

Radiograph and CT of osteoblastoma of the sacrum
AP and lateral radiographs of the lumbar spine show an expansile lesion in the right side of the S3 vertebral body. Axial CT without contrast through this level shows a large round lucent nidus with central calcification in the right S3 pedicle surrounded by sclerosis.

The diagnosis was osteoblastoma of the sacrum.