ANKYLOSING SPONDYLITIS-INVESTIGATION

SUMMARY

1. Radiograph changes often occur late (> 10 years).

2. MRI is more sensitive: shows marrow signal change adjacent to the SI joint.

3. Because of the high sensitivity (> 90%), a negative HLA-B27 test can exclude AS.

4. Ddx: diffuse idiopathic skeletal hyperostosis (DISH).

5. DISH X-ray findings include "flowing" osteophytes due to calcification of the ALL predominantly in the thoracic region (unlike lumbar spine in AS).

6. DISH is an incidental finding, affects men > 50yrs, rarely symptomatic, does not involve the SI joints and not assoc. with HLA-B27 or raised ESR/CRP.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].