Diffuse idiopathic skeletal hyperostosis
| Diffuse idiopathic skeletal hyperostosis | |
|---|---|
| Synonyms | Forestier's disease, senile ankylosing spondylosis, ankylosing hyperostosis |
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|
| DISH in an 80 year old female, also with T11 fracture. | |
| Classification and external resources | |
| Specialty | rheumatology |
| ICD-10 | M48.1 |
| ICD-9-CM | 721.6 |
| OMIM | 106400 |
| DiseasesDB | 4932 |
| eMedicine | article/1258514 article/388973 |
| Patient UK | Diffuse idiopathic skeletal hyperostosis |
Diffuse idiopathic skeletal hyperostosis (DISH) is a non-inflammatory spondyloarthropathy which predominantly affects the spine. It is characterized by ankylosis and enthesopathy (ossification of the ligaments and entheses). It most commonly affects the thoracic and thoraco-lumbar spine, but involvement is variable and can include the entire spine.
DISH is diagnosed by findings on x-ray studies. Radiographs of the spine will show abnormal bone formation (ossification) along the anterior spinal ligament. The disc spaces, facet and sacroiliac joints remain unaffected. Diagnosis requires confluent ossification of at least four contiguous vertebral bodies. Classically, advanced disease may have "melted candle wax" appearance along the spine on radiographic studies. In some cases, DISH may be manifested as ossification of enthesis in other parts of the skeleton.
The calcification and ossification is most common on the right side of the spine. In people with dextrocardia and situs inversus this calcification occurs on the left side, which confirms the role of the descending thoracic aorta in preventing the physical manifestations of DISH on one side of the spine.
Confluent ossification of multiple contiguous vertebral bodies in diffuse idiopathic skeletal hyperostosis (DISH)
"Melted candle wax" appearance of calcification and ossification in diffuse idiopathic skeletal hyperostosis (DISH). Note the preponderance on the right side.
Ectopic calcification and new bone formation in diffuse idiopathic skeletal hyperostosis (DISH)
DISH can present with spinal stiffness on forward flexion/back extension, or with mild back pain. It is symptomatic for thoracic spinal pain in approximately 80% of patients. Back pain or stiffness is worse in the morning in almost two-thirds of patients. It may also be asymptomatic and discovered as an incidental radiological abnormality. Dysphagia from cervical spine osteophyte impingement of esophagus is reported in some cases. Similar calcification and ossification may be seen at peripheral entheseal sites, including the shoulder, iliac crest, ischial tuberosity, trochanters of the hip, tibial tuberosities, patellae, and bones of the hands and/or feet.
The exact cause is unknown. Mechanical factors, dietary and long term use of some antidepressants may be of significance. There is a correlation between these factors but not a cause or effect. The distinctive radiological feature of DISH is the continuous linear calcification along the antero-medial aspect of the thoracic spine. The disease is usually found in people in their 60s and above, and is extremely rare in people in their 40s and 30s. 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 include paralysis, dysphagia (the inability to swallow), and pulmonary infections. Although DISH manifests in a similar manner to ankylosing spondylitis, these two are totally separate diseases. Ankylosing spondylitis is a genetic disease with identifiable marks, and affects organs. DISH has no indication of a genetic link, and does not affect organs other than the lungs, which is only indirect due to the fusion of the rib cage.
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