The exact cause is unknown. Mechanical, dietary factors and use of some medications (e.g. isotretinoin, etretinate, acitretin and other vitamin A derivatives) may be of significance. There is a correlation between these factors but not a cause or effect. The distinctive radiological feature of<unk>  is the continuous linear calcification along the antero-medial aspect of the thoracic spine.<unk>  is usually found in people in their 60s and above, and is extremely rare in people in their 30s and 40s. The disease can spread to any joint of the body, affecting the neck, shoulders, ribs, hips, pelvis, knees, ankles, and hands. The disease is not fatal; however, some associated complications can lead to death. Complications may include paralysis, dysphagia (difficulty swallowing), and lung infections. Although<unk>  manifests in a similar manner to ankylosing spondylitis, they are separate diseases. Ankylosing spondylitis is a genetic disease with identifiable marks, tends to start showing signs in adolescence or young adulthood, is more likely to affect the lumbar spine, and affects organs.<unk>  has no indication of a genetic link, is primarily thoracic and does not affect organs other than the lungs, and only indirectly due to the fusion of the rib cage. Long term treatment of acne with vitamin derived retinoids, such as etretinate and acitretin, have been associated with extraspinal<unk> .
Diffuse idiopathic skeletal hyperostosis
Hereditary multiple exostoses
Giant-cell tumor of bone
Fibrous dysplasia of bone
Gerodermia osteodysplastica
Paget's disease of bone
Malignant infantile osteopetrosis
Pycnodysostosis