Fat planes adjacent to the neural foramina are preserved. At the L5-S1 level, no focal disc herniation or protrusion is identified. A large soft tissue mass involving the superior portion of the left side of the sacrum is noted. The mass extends through the left S1 and S2 neural foramen and appears to expand these foramens. In addition, the mass extends superiorly in the spinal canal to the L5-S1 disc level.
Cortical destruction is evident postierolaterally.
No fluid levels or matrix is identified within this mass. The mass obliterates the left S1 and S2 nerve roots. Differential diagnosis includes primary neoplasms arising from within the neural foramen and primary osseous neoplasms. The differential includes chordoma, plasmacytoma, giant cell tumor, and metastases. The differential also includes neural sheath tumors such as neurofibroma.