Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterized by abnormal calcification/bone formation (

hyperostosis Hyperostosis is an excessive growth of bone. It may lead to exostosis. It occurs in many musculoskeletal disorders and from use of drugs like Isotretinoin. Disorders featuring hyperostosis include: * Camurati-Engelmann disease, type 2 * Hyper ...

) 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 vertebrate endoskeleton consisting of the bones, cartilages and ligaments that support the paired appendages ( fins, flippers or limbs). In most terrestrial vertebrates (except snakes, legless li ...

. In the spine, there is bone formation along the anterior longitudinal ligament and sometimes the posterior longitudinal ligament, which may lead to partial or complete fusion of adjacent

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

. The

facet Facets () are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cu ...

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. The ...

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 entheses, enthesis (pl. entheses). If the condition is known to be Inflammation, inflammatory, it can more pr ...

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

Signs and symptoms

Symptoms may include pain, stiffness, and restricted movements of the affected areas. 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

osteophyte Osteophytes are Exostosis, exostoses (bony projections) that form along joint margins. They are distinct from enthesophytes, which are bone, bony projections that form at the attachment of a tendon or ligament. Osteophytes are not always distingui ...

s may affect the esophagus or the larynx and cause

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

difficulty swallowing 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 li ...

or even

dyspnea Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that ...

. Similar calcification and ossification may be seen at peripheral entheseal sites, including the shoulder,

iliac crest The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterio ...

ischial tuberosity The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large posterior bony protuberance on the superior ramus of the ischium. It ...

, trochanters of the hip, tibial tuberosities,

patella The patella (: patellae or patellas), 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 m ...

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

DISH most commonly affects the elderly, especially 6th to 7th decades. The estimated frequency in the elderly is ~10% – 20%, with a slight male predominance. 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 used to treat skin diseases like harlequin-type ichthyosis, and lamellar ichthyosis, and severe cystic acne or moderat ...

, etretinate, acitretin and other

vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

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 l ...

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

ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis from the disease spectrum of axial spondyloarthritis. It is characterized by long-term inflammation of the joints of the spine, typically where the spine joins the pelvis. With AS, eye and bow ...

, 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 Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

with vitamin derived

retinoids The retinoids are a class of chemical compounds that are natural derivatives of vitamin A or are chemically related to it. Synthetic retinoids are utilized in cosmetic formulations, clinical dermatology, and the treatment of some forms of cancer ...

, 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 File:3DPOSTERIORRIBS (top) Nov 2018.jpg

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), and

physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

. 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