Diffuse Idiopathic Skeletal Hyperostosis (DISH)Dz

Synonyms: Forestier disease, ankylosing hyperostosis.

ICD-9 Code: 721.6.
ICD-10: M48.1

Definition: DISH is not an arthropathy, but rather a bone-forming diathesis primarily affecting the spine, with ossification of tendons and ligaments. Diagnosis is often incidentally found on chest radiography.

Etiology: The etiology of DISH is unknown.

Demographics: This common disorder occurs in 12% of those older than age 65 years. Men are more commonly affected than women by a ratio of 2:1.

Associated Disorders: DISH is associated with CPPD crystal deposition disease, gout, RA, and OA, but not AS. DISH may be associated with diabetes mellitus, obesity, hyperlipidemia, or hyperuricemia.

Cardinal Findings: Patients are usually asymptomatic but may complain of thoracolumbar or neck stiffness. Large osteophytes of the cervical spine may cause dysphagia in as many as 25% of patients. Enthesopathy is common. Large osteophytes elsewhere may cause recurrent Achilles tendinitis or tennis elbow.

Complications: Excessive heterotopic bone formation may complicate hip surgery. Relatively minor trauma may result in fractures through ankylosed segments with subsequent neurologic impairment. Rarely, ossification of the posterior longitudinal ligament may result in myelopathy.

Diagnostic Tests: Test results are normal for age (e.g., ESR). No association with HLA-B27 is seen in most studies.

Diagnostic Criteria: Resnick has proposed the following. All three criteria are required.
1. Flowing spinal calcification involving >4 contiguous vertebrae
2. Preservation of disc height and lack of degenerative disc disease
3. Absence of apophyseal and sacroiliac joint ankylosis or erosions

Imaging: Radiographic findings are diagnostic in DISH and include spinal and extraspinal findings.
—Spinal findings: There is normal bone mineralization. Anterolateral ossification of the anterior longitudinal ligament (and surrounding soft tissues) of the spine results in flowing, bridging, often bulky osteophytes that involve at least four contiguous vertebrae. Disc spaces are preserved. Involvement of the thoracic (nearly 100%), lumbar (>90%), and cervical spine (75%) is common.
—Extraspinal findings: Pelvic films are frequently abnormal with “whiskering” of the iliac crests, ossification of the symphysis pubis, or large bony osteophytes at the acetabular margin of the hip. The lower third (synovium-lined portion) of the sacroiliac joint should not be involved in DISH. Other sites of extensive ossification (or spurring) may include the calcaneus, patella, tibial tuberosity, and olecranon. Calcification of the sacrotuberous and iliolumbar ligaments may be seen.

Differential Diagnosis: AS, other spondylorthropathies, OA, intervertebral osteochondrosis, hypoparathyroidism, retinoid therapy, fluorosis, and hypervitaminosis A must be distinguished.

Therapy: No specific therapy retards development of new bone. Analgesic agents and NSAIDs may be used for pain or stiffness. Rarely is surgical removal of calcific masses indicated. The use of low-dose radiation after hip surgery to minimize heterotopic bone formation has not been tested.

BIBLIOGRAPHY

Belanger TA, Rowe DE. Diffuse idiopathic skeletal hyperostosis: musculoskeletal manifestations. J Am Acad Orthop Surg 2001;9:258–267.PMID:11476536

Mader R. Diffuse idiopathic skeletal hyperostosis: a distinct clinical entity. Isr Med Assoc J 2003;5:506–508.PMID:12901248