The radiological features of diffuse idiopathic skeletal hyperostosis (D.I.S.H.).

Diffuse idiopathic skeletal hyperostosis (D.I.S.H.) is a common disorder of unknown aetiology characterized by exuberant hyperostosis of the antero-lateral aspect of the spinal column, that sometimes leads to bone ankilosis, and by ossification of extra-spinal entheses. This condition is often associated with the metabolic derangement of type 2 diabetes. Primary hypertension, its cardiovascular aftereffects and lithiasis are also often present in these patients. D.I.S.H. has to be distinguished from osteoarthritis, although they often coexist in the same patient. The mean difference lies in the anatomical target of the pathological process, that is represented by articular cartilage in osteoarthritis and by entheses in diffuse idiopathic skeletal hyperostosis. The enthesopathy leads to the ossification of the anterior longitudinal ligament of the spine and causes the formation of flowing osteophytes, while intervertebral disc space is quite preserved in early phases of the disease. Symptoms of spine involvement are not typical of the disease and consist of pain and stiffness, usually worsened by inaction and damp. It has also been described the ossification of posterior longitudinal ligament which can lead to medullary canal stenosis. Appendicular skeleton is symmetrically involved in early phases of the disease, the most distinctive affected sites being feet, olecranus and patella. Hip involvement is also frequent and may lead to severe disability and represents an important cause of invalidity. The purpose of the present review is to remark on aetiopathogenetic and clinical aspects of diffuse idiopathic skeletal hyperostosis.