Hatchet sign (ankylosing spondylitis)

Hatchet sign
(ankylosing spondylitis) • Rotator cuff enthesitis in ankylosing spondylitis - Ganzer Fall bei Radiopaedia
Dixon, A. Rotator cuff enthesitis in ankylosing spondylitis. Case study, Radiopaedia.org. (accessed on 02 Nov 2022) https://doi.org/10.53347/rID-49769 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

Hatchet sign refers to the limited erosion of the lateral aspect of the humeral head that produces a hatchet-shaped deformity. This finding is typically associated with ankylosing spondylitis.

In the absence of osteoporosis and the presence of sclerosis, this sign helps to differentiate it from rheumatoid arthritis.

Differential diagnosis