• There is a large diffuse low T1, high T2, high STIR signal lesion at the sacrococcygeal region, arising from sacral foramen and extending out into pelvis.
• There is adjacent compressive scalloping from L5-S3, suggesting slow growth with further scalloping of the anterior coccyx.
• The lesion is intraspinal and effacing the thecal sac from L5 level. There is complete compression of the cauda equina nerve roots.
• The appearances are consistent with a large cystic sacral schwannoma with no actual intraosseous component.