36 y/o healthy female with neck pain following auto accident.

Good case.

100% classic ‘spondyloarthropathy’ in the wider sense of the term i.e. systemic inflammatory condition that targets joints and the axial skeleton especially. In that wider context, SAPHO syndrome may be considered a ‘spondyloarthropathy’ – but the classification of the non-infectious systemic inflammatory conditions of bones and joints is constantly changing and confusing. Are CRMO and SAPHO syndrome two different variations of the same theme but one mostly in peds and the other in adults?

Re your case:
Ankylosing spondylitis (AS) can affect bones as well as joints, and involvement bones of the chest wall is common in more florid AS. So it is a possibility. However one would definitely expect SIJ involvement.
Psoriatic Spondyloarthopathy will start in the spine without SIJ involvement much more often than AS, and also affects bones more often than AS – so TOP of my list.
SAPHO syndrome – depending on SIJ involvement (less often) could be high on my list. However extent of facet joint ankylosis is unusual for SAPHO
Reactive Arthritis possible.
Juvenile Spondyloarthritis (JSpA) distinctly possible – no age given.

Assuming adult, in order of likelihood:
Without SIJ involvement:
1. Psoriatic SpA
2. Psoriatic SpA
3. Other SpA’s – more bone involvement than usual
4. SAPHO syndrome – more facet joint ank than usual

With SIJ involvement:
1. Psoriatic SpA
2. AS
3. Other SpA’s
4. SAPHO syndrome

Full clinical history, labs and SIJ imaging will sort it out.

Cheers,

Rob

Most respondents said SAPHO.

Spoke with referring doc; ” she looks perfectly normal on physical exam.”

Referring to Rheumatology for work up
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2790148/