diffuse idiopathic skeletal hyperostosis (DISH) in comparison to ankylosing spondylitis (AS)

Last edited 11/2019 and last reviewed 12/2019

DISH in comparison to ankylosing spondylitis (AS):

  • defining imaging characteristics of DISH are the flowing osteophytes mainly in the thoracic spine
    • the coarse and thick bony spinal bridges form along the anterior longitudinal ligament in a more horizontal orientation and mainly on the right side
    • in ankylosing spondylitis (AS), the hallmark are thin, delicate vertically oriented syndesmophytes

  • usually older than the patients with AS and may have associated metabolic derangements such as obesity or diabetes

  • enthesopathy is another prominent feature in DISH, and crude entheseal calcification is a common finding in the pelvis as well as more peripheral joints such as the hands, ankles and feet

  • absence of sacroiliac (SI) joint erosions favoring DISH over AS
    • important to recognize the clinical overlap for milder conditions of SI joint pathology. For example, there are reports of SI osteophytes in patients with DISH

  • absence of apophyseal joint obliteration favoring DISH over AS

  • frequent ossification of the anterior longitudinal ligament (ALL) in DSH

  • absent enthesopathies with erosions favouring DISH over AS

  • no association with HLA-B27 favouring DISH over AS

  • DISH, compared to AS, tends to be a relatively mild or even painless disease
    • clinical symptoms are mild in comparison to the extensive radiographic or advanced imaging modalities
    • DISH is often discovered incidentally in asymptomatic


  • Weiss BG, Bachmann LM, Pfirrmann CW, et al. Whole body magnetic resonance imaging features in diffuse idiopathic skeletal hyperostosis in conjunction with clinical variables to whole body MRI and clinical variables in ankylosing spondylitis. J Rheumatol 2016;43:335-42.
  • Yaniv G, Bader S, Lidar M, et al. The natural course of bridging osteophyte formation in diffuse idiopathic skeletal hyperostosis: retrospective analysis of consecutive CT examinations over 10 years. Rheumatology 2014;53:1951-7.
  • T . David Luo; Matthew Varacallo. Diffuse Idiopathic Skeletal Hyperostosis (DISH). StatPearls.