Dermatomyositis: Myositis And The Skin
Dr. Sternberg’s presentation focused on how myositis affects the skin in a specific form of the disease called dermatomyositis. She also spoke about skin symptoms that were relevant to those with inclusion body myositis and polymyositis. Lastly, she highlighted different ways to care for your skin, which was a topic from which everyone in the workshop could benefit.
Dermatomyositis and Skin Symptoms
Dr. Sternberg began the presentation by defining dermatomyositis. She described that it results from an immune-mediated process triggered by outside factors (malignancy, drugs, infectious agents) in a genetically predisposed person.
In the research she described, the incidence of dermatomyositis/polymyositis has been estimated at 5.5 cases per million. The research she discussed finds that women are affected two times more commonly than men with the two peak ages of onset occurring at 5-10 years old and at age 50.
Dr. Sternberg described that when someone has dermatomyositis, the skin symptoms usually precede the muscle symptoms, which makes myositis challenging to diagnose. Without the muscle symptoms, it can be difficult for the doctor to identify what the cause of the skin symptoms (usually a rash) might be. Dr. Sternberg also pointed out that the severity and pattern of skin symptoms does not typically predict or correlate with the presence of the systemic involvement.
Your skin symptoms may get better or worse; however, your muscle symptoms may stay the same. Or, you may feel weaker but the skin symptoms may not get any worse. Myositis can affect the skin in a number of different ways, which are described below.
A rash is a common symptom of dermatomyositis. Most rashes occur in exposed areas and most patients find that the rash is often itchy and intense. Quality of life is often affected by a rash, especially if it is very visible on the face or causes severe itching. Additionally, an itchy rash can cause loss of sleep.
A recent study by Hundley et. al. was the first study to address the effect of the skin manifestations on Quality of Life Studies of patients with dermatomyositis. Prior to this study, most researchers traditionally focused on the impact of the muscle disease on quality of life. The data showed a profound impact of the dermatologic aspects of dermatomyositis, especially pruritus (itchiness), on quality of life.
A type of rash that those with myositis may experience is poikiloderma, which is a mottled, blotchy skin coloring. It tends to occur in sun-exposed skin. It is a combination of atrophy (skin thinning), telangiectasia (tiny blood vessels), and pigmentary changes (both hypopigmentation and hyperpigmentation).
Another skin symptom of myositis is called the “shawl sign,” which means that the person has poikiloderma in a V-shaped distribution over the neck, upper chest, and back.
Dermatomyositis is unique in that it tends to affect the skin over the joints, while other diagnoses, such as lupus, tends to affect the skin between the joints. There are several myositis symptoms that are visible on the hands.
Nailfold changes are a common symptom of myositis. The nailfold changes may be present as the first or only skin sign of myositis. It can look like ragged cuticles, or roughness, thickening, hemorrhages, and necrosis of the cuticles. There can also be cracking and fissuring of the distal digital skin (the fingerpads), often referred to as “mechanic hands.”
Gottron’s Papules (also known as Gottron’s Sign) is another symptom. This is described as a skin finding that is accentuated on bony prominences, especially knuckles, but also on elbows and knees; it causes them to become thicker and scaly.
Eyelid swelling may be an early sign of myositis. The “Heliotrope Sign” is another symptom of myositis related to the eyes. It may cause a subtle discoloration and mimic allergic reactions, but is less variable from day to day than most allergies.
Scalp and Hair Loss (alopecia)
Those with myositis may experience skin symptoms of the scalp. Symptoms may start out as a scaly scalp or diffuse hair loss. The hair loss may be temporary or permanent. The hair loss is often due to scarring of the scalp skin, loss of circulation to the hair follicle, and an autoimmune reaction. Hair loss often follows a flare of systemic disease or could be related to a side effect from medication.
Calcinosis is another symptom of myositis. It is usually seen in juvenile dermatomyositis and ranges from 44% - 70% vs. 20% in adults. Calcinosis refers to hard, irregular nodules that may drain a chalky white material on the skin. It typically occurs 2-3 years after onset and favors sites of trauma. It can be painful and may become infected.
Calcinosis most commonly involves elbows, knees, shoulders and buttocks, and it is often associated with a delay in starting steroid therapy or in treatment-resistant disease.
Medication Side Effects
Even when the muscle involvement and other systemic complications are completely controlled by medication, the skin disease may continue to be present. It may not be necessary to completely make the skin lesions "disappear" by giving increasing doses of immunosuppressive medications. Rather, most doctors prefer to treat the patient symptomatically. For example, treating the itch of a rash can have a large impact on the individual’s coping with myositis, even if the visible rash cannot be cured.
Some of the medications used to treat myositis can cause side effects related to the skin.
With systemic steroids, some of the short term side effects include:
• Mood changes
• Fluid and salt retention (swelling)
• Increased appetite, weight gain
• Amenorrhea (loss of menstruation)
• Increased infections
• Hyperglycemia (elevated blood sugar)
• Decreased wound healing
• Weight gain, particularly around midsection and upper back
• Rounding of your face (moon face)
• Fatty pad or hump between the shoulders (buffalo hump)
Osteoporosis is another symptom of steroids and Dr. Sternberg talked about this symptom in depth. She described that most of the significant demineralization in the bones occurs in the first 6-12 months of treatment. The bones most prone to osteoporosis are the ribs and the vertebrae (specifically the trabecular bone). She mentioned that the affects of osteoporosis are not minimized by alternate-day dosing, as some people believe. She highly recommends that individuals on steroids take calcium and vitamin D supplements, and see their rheumatologist for more information.
Other symptoms include skin atrophy (thinning) and hair loss, which may be due to the dermatomyositis itself or as a result of the administration of prednisone or other treatments such as methotrexate.
Skin side effects include:
• Thicker or more dense body and facial hair (hirsutism)
• Thin and fragile skin
• Easy bruising
• Slow healing of cuts, insect bites, and infections
• Acneiform eruptions
• Stretch marks (Striae)
Sun Exposure and its Effects on Dermatomyositis
Dr. Sternberg encouraged everyone to take precautions when their skin is exposed to the sun. The two types of sun rays are UVA and UVB. UVA rays penetrate deeper into the skin, which results in the darkening and pigmentation of the skin. UVA rays can also accelerate the aging process. Chronic, long-term exposure to UVA rays can make the skin appear dry, scaly, spotted, wrinkled, and leathery. The UVB rays are responsible for causing sunburn. Both UVA and UVB rays can cause skin cancers.
The rash of dermatomyositis is photodistributed and photoexacerbated (worsened by sun exposure), yet patients rarely report sun sensitivity. Photosensitivity in dermatomyositis has not been investigated extensively; however, many studies with lupus have been described. For those with lupus, both UVA and UVB rays have been shown to reproduce lesions. This research could mean that similar results would occur with dermatomyositis patients; however, it has not been fully explored yet.
Sunblock is one way to take precautions against the sun. When looking at the SPF (sun protection factor) of a sunscreen, the SPF measures the ability of the lotion to block UVB rays. An SPF of 15 blocks 93% of rays. An SPF of 30 blocks 97% of rays. Any SPF that is higher than 30 will block decimal points more of a percentage than SPF 30.
Dr. Sternberg gave some additional tips on how to protect your skin from the sun. She described that everyone should take the following precautions:
• Avoid peak sun hours (between 10 am and 4 pm)
• Sunscreen is very beneficial. They work by absorbing, reflecting, or scattering the sun’s rays. The higher the SPF, the greater the protection from UVB rays. Broad-spectrum sunscreens block out both UVA and UVB rays.
• Use broad-spectrum sunscreen with SPF of at least 30 on all sun-exposed areas, even on cloudy days
• Reapply sunscreen frequently; if exposed to water through swimming or sweating, use water-resistant sunscreen; reapply sunscreen every two hours
• Wear protective, tightly-woven clothing, wide-brimmed hat, sunglasses
• Beach umbrellas – good, but remember UV rays can bounce off sand, water, porch decks