Would sacral chordoma show up on a ultrasound? masses in sacral up to 4cm. no mass shows on us or xray.doc is leaving it at that.should i ask for ct?

I always ask if: Doing a test will change the management of the problem. If the treatment is the same, does this test need to be done? Do you, or does your doctor have any reason to doubt the diagnosis? You are better off asking for a second opinion when in doubt rather than another test. And if the test results won't affect what you do about it then the answer is clearly no. Think about this and discuss w/ MD.

Realize: Why plain x-rays and ultrasound are not the optimal means of imaging a sacral chordoma, it's unlikely that no abnormality would be seen. It's unclear what you mean but sacral mass up to 4 cm, is that on physical exam? More information is necessary to better advise you. Why the primary concern over a chordoma, you are on the young side and it's more common in men in that location?