Rheumatic disorders comprise over 100 different diseases, and typically affect joints, bones, muscles, ligaments (connect bones) and tendons (attach muscles to bones). The common symptoms are usually pain, stiffness, swelling, warmth and redness of the joints or muscles, tenderness, fatigue, weakness or impaired movement or function.

However, many of the disorders cause generalized or systemic problems and affect many other organ systems. In fact, the more severe ones can have dangerous effects on the kidneys, lungs, heart or brain. Surprisingly, there is a strong relationship between rheumatic disorders and skin disease. The list is quite extensive and includes: rheumatoid arthritis (nodules and vasculitis), lupus (facial and body rashes, vasculitis), dermatomyositis (facial and hand rashes), scleroderma (skin thickening, finger gangrene), juvenile inflammatory arthritis, infectious arthritis (including lyme disease and gonorrhea), gouty arthritis (nodules) and psoriatic arthritis (psoriasis).

Psoriasis affects around 2-4 percent of the American population, or about 7 million or more. Though there are a number of different forms, around 90 percent are plaque psoriasis (often with dry, scaly patches), and 15-30 percent of these patients will get psoriatic arthritis. Both psoriasis and psoriatic arthritis are considered “autoimmune” diseases, or ones generated by your immune system against your own tissues. The precise causes of the conditions are unknown, but up to 40 percent of cases have family members with the disorders.

The arthritis of psoriatic arthritis is typically a chronic condition, lasting many years, and can be mild or crippling. It is typically asymmetric, often involves only one or a few joints (oligoarticular). Sometimes swelling of a finger or toe can resemble a “sausage” (inflammation of the entire finger or toe, or dactylitis). In some cases, the spine is involved and causes profound spinal stiffness or fusion. It also has a nasty habit of involving the heel cords, soles of the feet or other tendon attachment. Nail pitting is common in patients with psoriatic arthritis. Recent studies have shown considerable risk of not treating the more aggressive forms with the very best therapies.

The diagnosis of psoriatic arthritis relies on the ability to identify the swollen joints in a person with psoriasis. A peak age for onset is between 30-50 years of age. Lab tests are of limited usefulness since there is no specific test at this time. The presence of elevated inflammatory blood tests (esr and crp) can be helpful, as well as x-rays or other imaging tests (MRI or CT, bone scan) showing inflammation or bone damage typical of the disease. Part of the workup will be to exclude other conditions. A skin biopsy can be required to confirm the diagnosis of psoriasis on occasion. The diagnosis of psoriatic arthritis is particularly difficult in the rare individual who develops the joint inflammation before the skin disease.

The treatment of psoriatic arthritis varies tremendously depending on how many joints are involved and how severe the impairment.

On occasion, simple pain medications such as NSAIDS (non-steroidal anti-inflammatory drugs) including naproxen, ibuprofen, meloxicam, celocoxib, etc. are used, but more severe cases require more aggressive medications. This might include methotrexate, leflunomide, azathioprine or cyclosporine, which are called DMARDs (disease modifying anti-rheumatic drugs). Local injections, physical therapy, even joint surgery are often used.

In 2002, Enbrel was the first biologic or targeted therapy approved for psoriatic arthritis. Remicade and Humira were then approved in 2005. Note that they were all later approved for the treatment of psoriasis. Since then, there are a number of other approved therapies including Simponi, Cimzia, Stelara and Cosentyx. Another product, Otezla, is not considered a biologic or targeted therapy but is approved for psoriatic arthritis, and, also unlike the others here, is a pill. These products are quite expensive, and except for the latter, are immunosuppressants, and will increase the risk of infection and possibly other problems. But the availability of these highly effective medications has revolutionized the treatment of the disorder.

As with other rheumatic diseases, the use of proper exercise and adequate diet can greatly enhance the overall health of these arthritic patients. Many of the common therapies applied to psoriasis alone are ineffective or not approved for the treatment of psoriatic arthritis, so do not assume that your light therapy, topical treatments or specific expensive biologic for psoriasis will necessarily “kill two birds with one stone” and also control inflammatory joint pain. Waiting to see your physician or provider after months or years of inflammatory joint pain greatly increases your risk of deformity, loss of function and poor outcome.

The association between rheumatic diseases and skin problems is strong, most apparent in those with psoriasis and psoriatic arthritis. However, those who suffer from any skin conditions and musculoskeletal disease should be aware of a possible association, seeking counsel from a physician or provider to clarify both diagnosis and treatment options.

Dr. Randal White, MD, FACP, FACR, is a rheumatologist at Vidant Rheumatology.