diffuse idiopathic skeletal hyperostosis

Diffuse idiopathic skeletal hyperostosis (DISH), also referred to as Forestier disease, is a common condition characterized by bony proliferation at sites of tendinous and ligamentous insertion of the spine affecting elderly individuals. On imaging, it is typically characterized by the flowing ossification of the anterior longitudinal ligament involving the thoracic spine and enthesopathy (e.g. at the iliac crest, ischial tuberosities, and greater trochanters). There is no involvement of the sacroiliac joints.

Epidemiology

DISH most commonly affects the elderly, especially 6th to 7th decades . The estimated frequency in the elderly is ~10% , with a male predominance.

Clinical presentation

The condition is commonly identified as an incidental finding when imaging for other reasons. However, spine stiffness and decreased mobility are referred to as possible symptoms.

Pathology

The etiology of DISH is still unknown. Histopathological features of spinal DISH include :

  • focal and diffuse calcification and ossification of the anterior longitudinal ligament
  • paraspinal connective tissue and annulus fibrosus
  • degeneration of the peripheral annulus fibrosus fibers
  • anterolateral extensions of fibrous tissue
  • hypervascularity
  • chronic inflammatory cellular infiltration
  • periosteal new bone formation on the anterior surface of the vertebral bodies
Location

The cervical and thoracic (particularly T7-11 ) spines, in particular, are affected. Additionally, enthesopathy may be identified in the pelvis and extremities.

Associations

Recognized associations include:

Radiographic features

Plain radiograph and CT
Spinal features
  • flowing ossifications: florid, flowing ossification along the anterior or right anterolateral aspects of at least four contiguous vertebrae
  • disc spaces are usually well preserved
  • ankylosis is more common in the thoracic than cervical or lumbar spine
    • frequently incomplete
    • can have interdigitating areas of protruding disc material in the flowing ossifications
  • no sacroiliitis or facet joint ankylosis
Extraspinal features
  • enthesopathy of the iliac crest, ischial tuberosities, and greater trochanters
  • spur formation in the appendicular skeleton (olecranon, calcaneum, patellar ligament) frequently present
  • 'whiskering' enthesophytes

Treatment and prognosis

DISH is generally managed clinically with analgesics and non-steroidal anti-inflammatory drugs when pain and stiffness are related. Possible complications may require specific treatment:

Differential diagnosis