Diffuse Idiopathic Skeletal Hyperostosis Overview

Diffuse Idiopathic Skeletal Hyperostosis, commonly referred to as DISH, is a disease characterized by calcification (deposition of calcium) and ossification (formation of bone) in soft tissues, primarily entheses and ligaments. First identified and described by Forestier and Rotes-Querol in 1950, the disease was then called "senile ankylosing hyperostosis." It has also been referred to as Forestier's disease.

In DISH, the axial skeleton is typically involved, especially the thoracic spine. But, when researchers realized that the disease was not limited to the spine and that it could affect peripheral joints, they re-named it Diffuse Idiopathic Skeletal Hyperostosis.

Symptoms and Characteristics

Characteristically, DISH involves the production of osteophytes along the right side of the thoracic spine (with intervertebral disk space unchanged) and ossification of the anterior longitudinal ligament. Calcification and ossification of the posterior longitudinal ligament can also occur in DISH, as well as entheseal areas, including the peripatellar ligaments, plantar fascia, Achilles tendon, olecranon (part of the ulna beyond the elbow joint), and more.

Diagnosis

A definitive diagnosis of DISH is based on radiographic findings, including:

• The presence of coarse, flowing osteophytes on the right side of the thoracic spine, connecting at least four contiguous vertebrae -or- ossification of anterior longitudinal ligament
• Preserved intervertebral disk height in the involved region
• The absence of apophyseal joint ankylosis, sacroiliac joint erosion, sclerosis, or intra-articular fusion. An apophyseal joint is a point where two or more bones join in the spine.

A probable diagnosis of DISH is based on continuous calcification, ossification, or both of the anterolateral region of at least two contiguous vertebral bodies, and corticated enthesopathies of the heel, olecranon, and patella. Also, peripheral enthesopathies may be indicative of early DISH which can later develop into the full-blown DISH that is evident radiographically.

Prevalence and Statistics

DISH is more common in men than women. The prevalence of DISH varies and is based on age, ethnicity, as well as geographic location. According to Kelley's Textbook of Rheumatology, hospital-based studies have reported the prevalence of DISH in men older than 50 years of age at approximately 25% versus women over 50 at 15%. Jews older than 40 years living in Jerusalem had a higher prevalence, while a lower prevalence was found among those in Korea (not even 9% of older people). Mild DISH was found in human remains dating back 4000 years. In human remains from the 6th to 8th centuries, the prevalence was higher in men compared to women, peaking around 3.7%.

Causes

The cause of DISH is not known, yet there are certain factors that appear to be associated with the condition. People with DISH often have osteoarthritis as well. DISH has also been associated with:

• Metabolic syndrome
• Diabetes mellitus (non-insulin dependent)
• Obesity
• High waist circumference ratio
• Hypertension
• Hyperinsulinemia
• Dyslipidemia
• Elevated levels of growth hormone
• Elevated insulin-like growth factor
• Hyperuricemia
• The use of retinoids (vitamin A substances)
• A genetic predisposition

Symptoms Associated With DISH

There are no signs and symptoms specifically associated with DISH. However, most DISH patients experience morning stiffness, dorsolumbar pain, and decreased the range of motion. There may be extremity pain of large and small peripheral joints as well as peripheral entheses (heel, Achilles tendon, shoulder, patella, olecranon). Pain in the axial skeleton may be attributed to all three regions of the spine, and the costosternal and sternoclavicular joints.

Treatment

Treatment of DISH is geared towards relieving pain and stiffness, slowing the progression of the disease, bringing metabolic disorders under control, and preventing complications. Light exercise, heat, pain medications, and nonsteroidal anti-inflammatory drugs (NSAIDs) are typically used to manage the consequences of DISH.