Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterized by abnormal calcification/bone formation ( hyperostosis) of the soft tissues surrounding the joints of the spine, and also of the peripheral or

appendicular skeleton The appendicular skeleton is the portion of the skeleton of vertebrates consisting of the bones that support the appendages. There are 126 bones. The appendicular skeleton includes the skeletal elements within the limbs, as well as supporting sh ...

. In the spine, there is bone formation along the

anterior longitudinal ligament The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs on their ventral side. It may be partially cut to treat certain abnormal curvature ...

and sometimes the posterior longitudinal ligament, which may lead to partial or complete fusion of adjacent

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

. The facet and

sacroiliac joint The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. T ...

s tend to be uninvolved. The thoracic spine is the most common level involved. In the peripheral skeleton, DISH manifests as a calcific

enthesopathy An enthesopathy refers to a disorder involving the attachment of a tendon or ligament to a bone. This site of attachment is known as the enthesis (pl. entheses). If the condition is known to be inflammatory, it can more precisely be called an ...

, with pathologic bone formation at sites where ligaments and tendons attach to bone.

Signs and symptoms

The majority of people with DISH are not symptomatic, and the findings are an incidental imaging abnormality. In some, the x-ray findings may correspond to symptoms of back stiffness with flexion/extension or with mild back pain. Back pain or stiffness may be worse in the morning. Rarely, large anterior cervical spine osteophytes may affect the esophagus or the larynx and cause

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

, difficulty swallowing or even dyspnea. Similar calcification and ossification may be seen at peripheral entheseal sites, including the shoulder, iliac crest, ischial tuberosity, trochanters of the hip, tibial tuberosities,

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...

e, and bones of the hands and/or feet. DISH can be a complicating factor when suffering from trauma involving the spine. It increases the risk of unstable fractures involving the intervertebral disc and the calcified/ossified ligaments which influences the need for surgical treatment.

Cause

The exact cause is unknown. Mechanical, dietary factors and use of some medications (e.g.

isotretinoin Isotretinoin, also known as 13-''cis''-retinoic acid and sold under the brand name Accutane among others, is a medication primarily used to treat severe acne. It is also used to prevent certain skin cancers (squamous-cell carcinoma), and in th ...

etretinate Etretinate (trade name Tegison) is a medication developed by Hoffmann–La Roche that was approved by the FDA in 1986 to treat severe psoriasis. It is a second-generation retinoid. It was subsequently removed from the Canadian market in 1996 and ...

, acitretin and other

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably ...

derivatives) 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. DISH 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 Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or liq ...

(difficulty swallowing), and lung infections. Although DISH manifests in a similar manner to

ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis characterized by long-term inflammation of the joints of the spine typically where the spine joins the pelvis. Occasionally areas affected may include other joints such as the shoulders or hi ...

, 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. DISH 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 Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...

with vitamin derived

retinoids The retinoids are a class of chemical compounds that are vitamers of vitamin A or are chemically related to it. Retinoids have found use in medicine where they regulate epithelial cell growth. Retinoids have many important functions throughou ...

, such as etretinate and acitretin, have been associated with ''extraspinal'' hyperostosis.

Diagnosis

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.Waldron, T. "Paleopathology". Cambridge University Press, 2009, p. 73. In some cases, DISH may be manifested as ossification, or 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. File:Thoracic spine Lat.png, Confluent ossification of multiple contiguous vertebral bodies in diffuse idiopathic skeletal hyperostosis (DISH) File:Thoracic spine AP.png, alt=DISH spine, "Melted candle wax" appearance of calcification and ossification in diffuse idiopathic skeletal hyperostosis (DISH). Note the preponderance on the patient's left side (right side of image). File:Calcification in Achilles tendon insertion and calcaneal spur.png, Ectopic calcification and new bone formation in diffuse idiopathic skeletal hyperostosis (DISH) File:Ossifikation Ligamentum longitudinale posterius HWS bei DISH - CT axial und sagittal - 001.jpg, Ossification of the posterior longitudinal ligament in DISH

Treatment

There is limited scientific evidence for the treatment for symptomatic DISH. Symptoms of pain and stiffness may be treated with conservative measures, analgesic medications (such as

non-steroidal anti-inflammatory drugs Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

), and

physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, pat ...

. In extraordinary cases where calcification or osteophyte formation is causing severe and focal symptoms, such as difficulty swallowing or nerve impingement, surgical intervention may be pursued.

References

External links