A 55-year-old Hispanic woman presents to her family physician with a diffuse rash and increasing muscle weakness. The initial rash (without weakness) 2 months prior was thought to be a photosensitivity reaction to her new hydrochlorothiazide (HCTZ) prescription. She stopped the HCTZ and the rash initially improved with some topical corticosteroids. At the time of her current presentation, she had trouble getting up from a chair, walking, and lifting her arms over her head. The rash was prominent in sun-exposed areas, but was also seen in a shawl-like distribution in non–sun-exposed areas (Figure 189-1). Aside from her hypertension and obesity, the patient did not have any previous chronic medical conditions. She was afebrile with no other pertinent findings on physical exam.
Initial presentation of dermatomyositis in a 55-year-old Hispanic woman. Prominent violaceous erythema with scale is visible on the chest, face, and arms. Deep-red erythema is especially visible on the side of the face. The scalp is red and scaling. (Reproduced with permission from Richard P. Usatine, MD.)
This is a classic presentation of dermatomyositis with the typical rash and proximal muscle weakness. Close attention to the rash around her eyes demonstrates the pathognomonic heliotrope rash of dermatomyositis (Figures 189-2 and 189-3). The patient also has Gottron papules on the fingers, seen best in this case over the proximal interphalangeal (PIP) joint of the third finger (Figure 189-4). There was periungual erythema and ragged cuticles. The scalp was red and scaly. Her neurologic exam was consistent with proximal myopathy. She also had some trouble swallowing bread; and dysphagia is not unusual in dermatomyositis. Laboratory tests showed mild elevations in muscle enzymes with the aspartate transaminase (AST) having the greatest elevation. In other cases, the creatine kinase (CK) can be very elevated.
Close-up of the heliotrope (violaceous) rash around the eyes of the patient in Figure 189-1. (Reproduced with permission from Richard P. Usatine, MD.)
View showing the bilateral heliotrope rash of the patient in Figure 189-1. A pathognomonic sign of dermatomyositis. (Reproduced with permission from Richard P. Usatine, MD.)
Hand involvement showing two Gottron papules over the knuckles (arrows) and erythematous nail folds (periungual erythema) in the patient in Figure 189-1. (Reproduced with permission from Richard P. Usatine, MD.)
The family physician started the patient on 60 mg of prednisone daily and topical steroids for the affected areas. The patient responded well to prednisone and 2 weeks later was feeling stronger and the rash was fading (Figure 189-5). After 4 weeks of 60 mg/day of prednisone she was started on 10 mg/wk of methotrexate in order to eventually taper her steroids. The patient has continued to do well, but the rash and muscle weakness tend to recur when her steroids are being tapered. The patient was sent for physical therapy and started on calcium and vitamin D supplementation to protect her from steroid-induced osteoporosis. She was also given 1 mg/day of folic acid to minimize the adverse effects of methotrexate. As dermatomyositis may be precipitated by an underlying malignancy, the physician screened the patient for internal cancers, especially ovarian cancer. Fortunately, the mammogram, Papanicolaou (Pap) smear, colonoscopy, transvaginal ultrasound for ovarian imaging, and abdominal/pelvic CT scans were all normal.
Patient improving after 2 weeks of oral prednisone. The heliotrope rash is still visible around the eyes and upper chest. The hairline erythema is from scalp involvement. (Reproduced with permission from Richard P. Usatine, MD.)
Dermatomyositis is a rare, idiopathic inflammatory disease involving the striated muscles and the skin. The disease is characterized by progressive, symmetric, proximal muscle weakness. Dermatologic manifestations may occur with or without muscular disease and include the characteristic heliotrope rash (Figures 189-2, 189-3, 189-5, and 189-6), "shawl sign," and Gottron papules of the PIP joints. Although primarily a disease of muscle and skin, dermatomyositis has a clear association with calcinosis, myocarditis, and interstitial lung disease, as well as an increased risk of underlying malignancy.
Classic heliotrope rash around the eyes of this 19-year-old woman newly diagnosed with dermatomyositis. The color "heliotrope" is a pink-purple tint named after the color of the heliotrope flower. As expected, her heliotrope rash is bilaterally symmetrical. This rash resolved on prednisone and hydroxychloroquine. (Reproduced with permission from Goodall J, Usatine RP. Skin rash and muscle weakness, J Fam Pract. 2005;54(10):864-868. Frontline Medical Communications, Inc.)
Annual incidence of 5 to 8.9 per 1 million population.1
Seen more commonly in women.1
Bimodal age distribution, most commonly affecting adults 45–64 years old and much less commonly children 5–14 years old; however, any age can be affected.1
35% to 40% of patients with dermatomyositis also have interstitial lung disease (ILD). It is the most common internal organ manifestation of the disease and greatly affects morbidity and mortality.1,2
Has been linked to malignancy in up to 15% to 24% of adults.3
Cancers most commonly associated are breast, ovarian, lung, GI tract, and hematologic.4 The most common type of cancer is adenocarcinoma. Ovarian cancer is overrepresented in those patients with dermatomyositis and cancer. Cancer is not typically seen in children with dermatomyositis.
Risk factors for malignancy include age over 45, male sex, and the presence of specific autoantibodies. TIF-1γ autoantibodies have been associated with increased risk, as well as anti-p155 autoantibodies, which have shown a 27-fold increase in odds.5,6
Certain cutaneous manifestations have also been found to be risk factors for underlying malignancy. The finding of skin necrosis has the strongest association, with a twofold increase in odds. The presence of skin ulcerations has also been associated with increased risk.7
Several protective factors have been identified. Younger age, TIF-1γ and p155 antibody–negative status, and concurrent ILD are associated with a lower risk of occult malignancy.8
ETIOLOGY AND PATHOPHYSIOLOGY
Dermatomyositis is considered an autoimmune disease of unknown etiology. Environmental exposure and infectious agents may play a role in disease pathogenesis.
Dermatomyositis has been shown to be a microangiopathy that affects the skin and muscle. The muscle weakness and skin manifestations may be a result of activation and deposition of complement, which cause lysis of endomysial capillaries and muscle ischemia.
Diagnosis includes 5 criteria and may be categorized as: "definite" (skin findings plus any 3 of criteria 1 to 4), "probable" (skin findings plus 2 of any criteria 1 to 4), or "possible" (skin findings plus any 1 of criteria 1 to 4).2,9,10
Skin findings—The heliotrope rash and Gottron papules are considered pathognomonic (Figures 189-2, 189-3, 189-4, 189-5, 189-6, 189-7, 189-8). Nonpathognomonic manifestations include malar erythema and periungual and cuticular changes (Figure 189-9).
Proximal symmetric muscle weakness that progresses over weeks to months.
Elevated serum levels of muscle enzymes (CK, AST, lactate dehydrogenase [LDH] and aldolase).
Abnormal electromyogram (EMG).
Abnormal muscle biopsy with muscle necrosis or inflammatory infiltrate.
These criteria are still considered the "gold standard," although they are old (1975) and currently under critical review because of several limitations. Expanded criteria have been proposed that include MRI findings in the thigh muscles and specific autoantibodies.2,8,11,12
Hand involvement in the 19-year-old woman in Figure 189-6 with Gottron papules over the finger joints. She has nail-fold erythema and ragged cuticles (Samitz sign). (Reproduced with permission from Goodall J, Usatine RP. Skin rash and muscle weakness, J Fam Pract. 2005;54(10):864-868. Frontline Medical Communications, Inc.)
Juvenile dermatomyositis in a young boy. Note how the erythematous papules and plaques are most prominent over the finger joints and spare the space between joints. This is a good example of Gottron papules being very visible in juvenile dermatomyositis. (Reproduced with permission from Goodall J, Usatine RP. Skin rash and muscle weakness, J Fam Pract. 2005;54(10):864-868. Frontline Medical Communications, Inc.)
Dermatomyositis in a man showing cuticular changes that are thick, rough, and hyperkeratotic with telangiectasias. This moth-eaten appearance of the cuticles is called the Samitz sign. The hands also have the appearance of "mechanic's hands," another sign seen in dermatomyositis. (Reproduced with permission from Richard P. Usatine, MD.)
Recent studies indicate that the finding of dilated nail-fold capillary loops (Figure 189-10) often seen in patients with dermatomyositis may assist in earlier diagnosis and predicting patients with poor prognosis. Dilated nail-fold capillary loops have shown promise in juvenile dermatomyositis as a marker for both skin and muscle disease activity to guide treatment. Some authors propose adding this finding to criteria for diagnosis.13,14
Dilated nail-fold capillary loops visible with dermoscopy in a young woman with newly diagnosed dermatomyositis. The nail-fold findings resolved with treatment. (Reproduced with permission from Richard P. Usatine, MD.)
Bilateral periorbital heliotrope erythema (pathognomonic) (see Figures 189-2, 189-3, 189-5, and 189-6) and scaling violaceous papular dermatitis in a patient complaining of proximal muscle weakness points to dermatomyositis.
The patient may classically complain of difficulty climbing stairs, rising from a seat, or combing their hair. Notably the skin manifestations may precede, follow, or present simultaneously with muscle involvement; a patient may even have skin manifestations for longer than a year prior to developing muscle weakness.
Hand involvement includes abnormal nail folds and Gottron papules. "Moth-eaten" cuticles, also called the Samitz sign, are evidenced by periungual erythema and telangiectasias (see Figures 189-7, 189-8, 189-9).
Gottron papules, smooth, purple-to-red papules and plaques, are classically located over the knuckles and on the sides of fingers (see Figures 189-4, 189-7, and 189-8). Plaques may be present over the knuckles instead of or in addition to papules. The papules are especially evident in juvenile-onset dermatomyositis (see Figure 189-8).
Dysphagia can be present as a consequence of pharyngeal muscle involvement with risk of aspiration and pneumonia.
Patients with concurrent interstitial lung disease may also present with fatigue, cough, dyspnea on exertion, and decreased exercise tolerance. Lung involvement usually appears following symptoms of myositis, although this is not always the case.2
Face—The characteristic heliotrope rash occurs around the eyes. The color "heliotrope" is a pink-purple tint named after the color of the heliotrope flower. This color is best seen in Figure 189-6. The heliotrope rash can also be a dusky-red color as seen in Figures 189-1, 189-2, 189-3, 189-4, 189-5. This heliotrope rash is bilaterally symmetrical.
Hands—There is usually hand involvement with Gottron papules (and plaques), visible nail-fold capillaries, and abnormal cuticles (see Figures 189-4 and 189-7 to 189-9).
Neck and upper trunk—A red or poikiloderma-type rash can be seen in a V-neck (Figure 189-11) or shawl distribution (Figure 189-12). Poikiloderma refers to hyperpigmentation of the skin demonstrating a variety of shades with associated telangiectasias. The rash here can be scaling and look psoriasiform.
Extremities may have erythematous plaques and papules with scale. If the erythema and scale is on the upper outer thigh, it is called the holster sign (Figure 189-13).
Scalp is often involved with erythema, scale, and pruritus. This is similar to seborrhea or psoriasis.
Sun-exposed areas are often involved and worsen with sun exposure. This is why so many of the skin findings are on the face and upper chest (Figure 189-14). However, patients rarely complain of sun sensitivity.
Poikiloderma (erythema and mottled hyperpigmentation) on the neck of a 35-year-old Hispanic woman with dermatomyositis. The V-neck distribution is related to sun exposure. (Reproduced with permission from Goodall J, Usatine RP. Skin rash and muscle weakness, J Fam Pract. 2005;54(10):864-868. Frontline Medical Communications, Inc.)
The shawl distribution of dermatomyositis. (Reproduced with permission from Richard P. Usatine, MD.)
Holster sign showing erythema and scale on the lateral thigh. Note the Gottron papules on the fingers. (Reproduced with permission from Richard P. Usatine, MD.)
A flare of dermatomyositis in a patient previously under control on medications now showing erythema on the lateral face, upper chest, and proximal arm. (Reproduced with permission from Richard P. Usatine, MD.)
LABORATORY STUDIES AND DIAGNOSTIC TESTS
Elevated muscle enzymes, evidence of inflammation on electromyography (EMG), and inflammatory infiltrates on muscle biopsy confirm the diagnosis of dermatomyositis. The following serum muscle enzymes can be drawn during the acute active phase and may be found to be elevated: CK, lactate dehydrogenase (LDH), alanine transaminase (ALT), AST, and aldolase. Of note, it is necessary to measure all of the aforementioned enzymes, as only one of them may be elevated.
The diagnosis may be made with confidence in a patient with characteristic skin findings and elevated muscle enzymes. If the presentation is not straightforward, then EMG, MRI of the thigh muscle, and/or muscle biopsy should be performed.
The diagnosis can be supported with positive antibodies such as antinuclear antibody (ANA), anti-Mi-2, and anti-Jo-1. It is not necessary to order these antibodies to make the diagnosis of dermatomyositis. In fact, these myositis-specific antibodies are positive in only 30% of patients with dermatomyositis. Patients with anti-Mi-2 generally have a better overall prognosis.
Some experts recommend initial pulmonary function tests (PFTs), chest radiograph, and high-resolution CT to identify patients with interstitial lung disease early, regardless of the presence or absence of respiratory symptoms.15
PFTs demonstrate a restrictive pattern and decreased diffusing capacity when interstitial lung disease is present. Abnormal results must be confirmed by CT scan, as PFT results may also reflect coexisting respiratory muscle weakness. Changes over time can be used to determine response to therapy, although intervals for testing are not clearly defined.2
Dermoscopy of the proximal nail folds (cuticles) often shows dilated capillary loops with dropout of vessels between the loops (see Figure 189-10).
Other papulosquamous diseases, such as lichen planus and psoriasis, may be differentiated from dermatomyositis with a 4-mm punch biopsy, but the histology of dermatomyositis is indistinguishable from cutaneous lupus erythematosus.
Muscle biopsy of dermatomyositis will show inflammatory cells around intramuscular blood vessels. Atrophic muscle fibers are seen around the periphery of muscle fascicles ("perifascicular atrophy").1
Polymyositis is another form of inflammatory myopathy. It is distinguished from dermatomyositis by its lack of cutaneous involvement. Dermatomyositis can also occur without muscle involvement. This is called dermatomyositis sine myositis or amyopathic dermatomyositis.
Polymorphous light eruption or other photosensitivity reactions may be mistaken for the dermatologic findings of dermatomyositis. In the case of our patient, her cutaneous findings preceded her muscle weakness, and the cutaneous findings were only in light-exposed areas. Therefore, it is essential in the management and follow-up of patients with suspected photosensitivity reactions to inquire about muscle weakness and to look for other signs of dermatomyositis. Examination of the hands and tests for muscle enzyme elevations might help to distinguish dermatomyositis from photosensitivity reactions (see Chapter 208, Photosensitivity).
Hypothyroidism can cause a proximal myopathy just like polymyositis and dermatomyositis. Although hypothyroidism can cause a dermopathy, it does not resemble the skin findings of dermatomyositis. All patients with proximal muscle weakness should have a screening thyroid-stimulating hormone (TSH) to rule out hypothyroidism regardless of their skin findings (see Chapter 235, Goitrous Hypothyroidism).
Rosacea causes an erythematous rash on the face as is often seen in dermatomyositis. Of course rosacea does not cause muscle weakness and the erythema of rosacea is generally limited to the face (see Chapter 119, Rosacea).
Steroid myopathy may develop as a side effect of systemic steroid therapy. The symptoms develop 4 to 6 weeks after starting oral steroids for dermatomyositis and other autoimmune diseases. Therefore, if muscle weakness recurs after initial improvement, it may be from the steroids, not the disease itself.
Dermatomyositis-like reaction rarely may present with similar skin findings after initiation of the following medications and improve with their discontinuation: penicillamine, nonsteroidal anti-inflammatory drugs (NSAIDs), and carbamazepine.
Overlap syndrome—The term overlap denotes that certain signs are seen in both dermatomyositis and other connective tissue diseases, such as scleroderma, rheumatoid arthritis, and lupus erythematosus. Scleroderma and dermatomyositis are the most commonly associated conditions and have been termed sclerodermatomyositis or mixed connective disease. In mixed connective tissue disease, features of systemic lupus erythematosus (SLE), scleroderma, and polymyositis are evident, such as malar rash, alopecia, Raynaud phenomenon, waxy-appearing skin, and proximal muscle weakness.
Given the autoimmune mechanism central to the disease process, treatment is geared toward the proximal muscle weakness and skin changes using immunosuppressive or immunomodulatory therapy. Treatment is nonspecific, as the target antigen remains elusive.5 Cutaneous manifestations do not always parallel muscle disease in response to therapy. Clinical improvement should guide treatment, as serum CK level may falsely normalize during therapy and should not be used as a sole gauge of responsiveness to treatment. Effective therapies for the myopathy are oral corticosteroids, immunosuppressants, biologic agents, and/or intravenous immunoglobulin. Effective therapies for the skin disease are sun protection, topical corticosteroids, antimalarials, methotrexate, and/or immunoglobulin. Drug therapy for dermatomyositis continues to be based on empirical rather than evidence-based practice due to lack of controlled trials.16
Physical and/or occupational therapy to regain strength is highly recommended. Physical therapy will preserve muscle function and help to prevent atrophy and contractures.17
Aerobic exercise has been shown to improve muscle performance and the achievement of activities of daily living (ADLs), but regression to baseline performance was seen at follow-up, demonstrating the need for a sustained exercise regimen.18
In combination with exercise, oral creatine supplement in juvenile dermatomyositis was shown to improve muscle endurance and functionality compared to placebo.19 Although creatine supplementation was well tolerated in patients with juvenile dermatomyositis, it does not show therapeutic benefit in adult populations.20
Patient education is crucial, emphasizing the photosensitive nature of the skin lesions and encouraging photoprotection consisting of broad-spectrum sunscreen, protective outerwear, and limiting sun exposure.21-23 SORⒷ
Therapy of the skin disease should include high-potency topical corticosteroids.21,22,24 SORⒷ Triamcinolone ointment may be used for less-severe areas or on the face at first. Consider a short course of a very high-potency steroid, such as clobetasol, for more severe involvement not on the face.9
Topical tacrolimus 0.1% is a useful adjunct in the treatment of refractory skin manifestations.17 SORⒷ
If disease is limited to the skin, antimalarial agents in addition to topical corticosteroids are first-line therapy. Hydroxychloroquine is most commonly used at 200 mg to 400 mg daily in adults (maximum of 5 mg/kg of real body weight per day),25 but patients with dermatomyositis are at increased risk of a drug eruption with this medication, and a morbilliform eruption may develop in 25% of patients. If this is the case, patients have been shown to tolerate chloroquine instead. These antimalarial agents have a rare side effect of retinopathy and require a baseline ophthalmologic exam before treatment is initiated, and yearly after 5 years during the duration of treatment.25
First-line therapy for muscle disease is high-dose (1 mg/kg single daily dose) oral prednisone, with or without an immunosuppressive ("steroid-sparing") agent—methotrexate, cyclosporine, mycophenolate mofetil, or azathioprine.3 The steroid-sparing immunosuppressive medication can be started after the patient is responding to the prednisone and be used to continue therapy while tapering down the dose of prednisone.
Corticosteroids (either IV or oral) are also the first-line treatment for interstitial lung disease in patients with dermatomyositis. Approximately half of patients show response in respiratory symptoms. Refractory cases are treated with cyclosporine or cyclophosphamide, with or without corticosteroids. Methotrexate use is cautioned when there is coexisting lung disease, as it is a known cause of drug-induced interstitial lung disease.2,26
To avoid the toxic effects of steroids, steroid taper (20% to 25% reduction monthly) should be initiated based on clinical responsiveness (increased muscle strength, energy) after 3 to 4 weeks on high-dose treatment.
If no response by 3 months to oral high-dose steroids, another treatment approach should begin along with a reexamination of the diagnosis.3,17 SORⒷ
Methotrexate is the most commonly used steroid-sparing agent in treating the muscular symptoms of childhood and adult refractory dermatomyositis. Methotrexate significantly improves skin lesions as well.27 SORⒷ
Methotrexate dosing starts at 10 to 15 mg/wk. The dose is then increased 2.5 mg/wk until a total dose of 15 to 25 mg/wk is reached. The total dose of methotrexate is also determined by how well the patient can tolerate this medication. Improvement is typically noted after 4 to 8 weeks of therapy.17,24
Using methotrexate safely requires a number of precautions. A purified protein derivative (PPD) should be placed or a QuantiFERON-TB Gold assay performed to make sure that latent tuberculosis will not be activated. Patients with active liver disease, including hepatitis C and alcoholic cirrhosis, should receive alternative forms of therapy, as methotrexate can be hepatotoxic. Women should avoid becoming pregnant during therapy, and men should also use contraception. Persons started on methotrexate should also be given 1 mg of folic acid daily to minimize the risk of side effects such as myelosuppression. The patient should be followed with regular laboratory testing, including complete blood counts and comprehensive metabolic profiles. Methotrexate should only be prescribed by doctors familiar with its risks and benefits.
As the methotrexate dosage is increased, the dosage of prednisone should be tapered.
Cyclosporine plus methotrexate has shown some benefit in the treatment of refractory juvenile and adult dermatomyositis.17 SORⒷ Cyclosporine should be used cautiously, with monitoring of blood pressure, renal function, liver function, and hematologic parameters.
New data show that methotrexate and cyclosporine both result in clinical improvement with no difference in efficacy or toxicity.17
Azathioprine is commonly used in chronic inflammatory diseases as a steroid-sparing agent. It is usually administered up to 2 to 3 mg/kg per day. Azathioprine has been shown to have a slower clinical effect than methotrexate, but no difference was noted in efficacy of treatment of muscle disease.17 Azathioprine is less effective for the treatment of cutaneous lesions. Like all the other immunosuppressive agents, azathioprine must be used cautiously and by physicians familiar with its risks.
It is important to look at these medications' side-effect profile and monitor the patient accordingly during treatment. Patients must not get pregnant while on these medications, and various labs need to be followed. The role of liver biopsy in methotrexate use is debated and should be considered based on the most current guidelines and standards of care.
Tacrolimus has effects similar to cyclosporine but has greater potency and is effective in refractory juvenile dermatomyositis.17 In addition, tacrolimus has been shown to have great success in stabilizing or improving ILD and may be a good option for patients with comorbid interstitial lung disease.28
Mycophenolate mofetil, an inhibitor of T- and B-cell proliferation, is a possible corticosteroid-sparing agent that has shown efficacy for both refractory cutaneous and muscular disease; however, concern regarding central nervous system (CNS) B-cell lymphoma and lack of controlled trials limits its use. It is also more costly than methotrexate or azathioprine.
Hydroxychloroquine is one option for a steroid-sparing agent, especially for the rash of dermatomyositis, which may be considered for young women with mild disease. SORⒸ Quinacrine and isotretinoin have shown promise in rashes that are unresponsive to hydroxychloroquine.17
Various combination therapies with two of the following agents have been studied but are still empirical: azathioprine, cyclosporine, intramuscular methotrexate, and oral methotrexate.23,24,29 SORⒸ
Biologics, including tumor necrosis factor (TNF)-α inhibitors, are currently being tested for use in juvenile and adult dermatomyositis. Conflicting and discouraging initial results prompt the need for further clinical trials. Interferon-β, monoclonal complement antibodies, and anti–T-cell signaling drugs are currently under investigation.
Pulsed intravenous methylprednisolone has been advocated for severe disease (especially juvenile cases) and in refractory cases of myositis.30 SORⒸ This treatment has also been recommended as first-line therapy for patients with associated interstitial lung disease.1
In patients who are not responsive to traditional therapies, recent studies have found intravenous immunoglobulin (IVIG) to be an effective and relatively safe second-line therapy. Studies show improvement in muscle histology and cutaneous disease. Higher remission rates after 4 years are seen in patients receiving IVIG as part of therapy. IVIG is dosed 2 g/kg over 3 to 6 months with treatment for 2 to 5 consecutive days each month. As opposed to other agents that take months to show effect, IVIG may show clinical improvement within 15 days of the first infusion, and maximal efficacy is seen after the second or third infusion.31 Recent studies reveal that there may be a survival benefit when IVIG is used as part of initial therapy.31 High cost limits current use.16,17 SORⒸ
Rituximab, a chimeric antibody against CD20+ B cells, has shown mixed results in different studies. In some studies, it has shown efficacy in patents refractory to conventional therapy who have failed an average of 3 disease-modifying anti-rheumatic drugs (DMARDs).32,33 However, the median time to measurable clinical improvement was 20 weeks.33 Although rituximab is very expensive, these results are promising for patients who are unresponsive to prednisone, methotrexate, and other conventional therapies.32
All patients with dermatomyositis, regardless of age, should undergo an age- and gender-relevant malignancy work-up beginning at the time of diagnosis. Cancer may be diagnosed before or after the diagnosis of dermatomyositis, but malignancy risk is highest within 1 year of diagnosis. Some studies show an increased risk up to 5 years following diagnosis.11,30
Cancer is rare in juvenile dermatomyositis, so these patients do not need an extensive malignancy evaluation.6
For adults, evidence-based guidelines for cancer screening have not been defined, leading to ambiguity about how to approach the malignancy work-up. Screening should be performed with risks attributed to age, gender, ethnicity, and family history in mind.6,11
Despite the lack of published guidelines, algorithms have been proposed that stratify adult patients based on the presence of anti-TIF-1γ. Individuals positive for the antibody are recommended to undergo the most aggressive evaluation for occult malignancy, which may consist of whole-body PET/CT at the time of diagnosis and annually for the next 3–5 years. For patients who are anti-TIF-1γ negative, a full-body PET/CT upon diagnosis may be sufficient.6
Alternatively, if antibody testing is unavailable, women newly diagnosed should undergo a pelvic and transvaginal ultrasound, mammogram, and CT thorax and abdomen, or a full-body PET scan. Colonoscopy is recommended in patients older than age 50 years or with risk factors.27
For men, a testicular and prostate exam should be performed at diagnosis with colonoscopy if age older than 50 years.34
If primary screening is negative, some experts recommend that a patient should be screened again in 3 to 6 months and every 6 months up to 4 years following diagnosis. Risk factors for underlying malignancy should be kept in mind, such as male sex, age older than 45 years, and the presence of skin necrosis. The cumulative risk factors should be balanced against the risks of exposing the patient to repeated radiation with successive screening.6,11,34
The value of surveillance of tumor markers such as CA-125 and CA-19-9 is debatable.11,34
Given its suggestive high predictive value, some experts recommend more intensive and frequent screening for patients positive for the anti-p155 or anti-TIF-1γ antibodies.5
In one study, conventional cancer screening (thoracoabdominal CT, mammography, gynecologic examination, ultrasound, and tumor marker analysis) and fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT total-body screening had equivalent overall predictive values for diagnosing malignancy in patients with myositis.35
Recent reports indicate that approximately 20% to 40% of patients treated achieve remission, although 80% of treated patients remained disabled. One study found the mortality rate of patients with dermatomyositis to be threefold higher than the rest of the population. Cancer, lung, and cardiac complications are the most common cause of death. Poor prognostic indicators include older age, cardiac and lung involvement (ILD), and dysphagia. Certain antibodies have also been linked to higher mortality rates and greater risk of malignancy.8
Patients need very close and frequent follow-up to manage their medications and overall care, as well as continued surveillance for malignancy. High doses of steroids and steroid-sparing agents, such as methotrexate, have numerous potential side effects. Patients need to be closely followed with laboratory tests and careful titration of the toxic medicines used for treatment. Patients also need physical therapy, periodic eye exams for cataracts and glaucoma, and specific supplements including calcium, vitamin D, and folic acid to prevent some of the side effects of the strong medications being prescribed. Patients on long-term corticosteroids especially need efforts made to prevent and detect osteoporosis.
Discuss the importance of sun protection, as sun exposure makes the cutaneous manifestations worse. Counseling about the serious nature of the disease and prognosis is important, as many patients are left with residual weakness even after good disease control is obtained. Patients need to understand that the medications being used have many risks along with their benefits and need to report side effects to their physicians. Pregnancy prevention is needed for women of childbearing potential while on a number of the medications used to treat this disease.
AM. Clinical features, pathogenesis and treatment of juvenile and adult dermatomyositis. Nat Rev Rheumatol.
SK. Interstitial lung disease associated with the idiopathic inflammatory myopathies: what progress has been made in the past 35 years. Chest.
MC. Immunotherapy of inflammatory myopathies: practical approach and future prospects. Curr Treat Options Neurol.
FC. Cancer risk in dermatomyositis: a meta-analysis of cohort studies. Am J Clin Dermatol
et al. Usefulness of anti-p155 autoantibody for diagnosing cancer-associated dermatomyositis. Arthritis Rheum.
AL. Idiopathic inflammatory myopathies and malignancy: a comprehensive review. Clin Rev Allergy Immunol
et al. Meta-analysis of the association of dermatomyositis and polymyositis with cancer. Br J Dermatol
I. Morbidity and mortality in adult polymyositis and dermatomyositis. Curr Rheumatol Rep.
JB. Polymyositis and dermatomyositis (first of two parts). N Engl J Med.
JB. Polymyositis and dermatomyositis (second of two parts). N Engl J Med.
RG. Defining cancer risk in dermatomyositis. Part I. Clin Exp Dermatol.
DA. Re-classifying myositis. Rheumatology (Oxford)
et al. Nailfold capillary density is importantly associated over time with muscle and skin disease activity in juvenile dermatomyositis. Rheumatology. 2011;50(5):885–893.
et al. Nailfold capillary microscopy in adults with inflammatory myopathy. Semin Arthritis Rheum.
et al. Interstitial lung disease, a common manifestation of a newly diagnosed polymyositis and dermatomyositis. Ann Rheum Dis.
et al. Intravenous immunoglobulin therapy in adult patients with polymyositis/dermatomyositis: a systematic literature review. Clin Rheumatol.
CV. Therapeutic approaches in myositis. Curr Rheumatol Rep.
et al. Improvement in health and possible reduction in disease activity using endurance exercise in patients with established polymyositis and dermatomyositis: a multicenter randomized controlled trial with a 1-year open extension followup. Arthritis Care Res (Hoboken)
et al. Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: six-month, double-blind, randomized, placebo controlled trial. Arthritis Rheum.
RD. Treatment of dermatomyositis with methotrexate
. J Am Acad Dermatol
. 1995;32(5 Pt 1):754–757.
JP. Dermatomyositis: diagnosis, evaluation and management. Minerva Med.
RL. Dermatomyositis. Clin Dermatol.
DA. Treatment of dermatomyositis and polymyositis. Rheumatology (Oxford).
T. A Color Guide to Diagnosis and Therapy, Clinical Dermatology, 4th ed. St. Louis, MO: Mosby; 2004.
Y. Interstitial lung disease in myositis: clinical subsets, biomarkers, and treatment. Curr Rheumatol Rep.
et al. Efficacy of low-dose methotrexate
in the treatment of dermatomyositis skin lesions. Clin Exp Dermatol.
et al. The efficacy of tacrolimus
in patients with refractory dermatomyositis/polymyositis: a systematic review. Clin Rheumatol.
JB. Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis. Cochrane Database Syst Rev. 2005;(3):CD003643.
AN. Malignancy in myositis. Curr Rheumatol Rep.
M. Critical review of the role of intravenous immunoglobulins in idiopathic inflammatory myopathies. Semin Arthritis Rheum
et al. Rituximab
treatment in patients with refractory inflammatory myopathies. Rheumatology.
et al. Rituximab
in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis: a randomized, placebo-phase trial. Arthritis Rheum.
et al; European Federation of Neurological Societies. Screening for tumors in paraneoplastic syndromes: report of an EFNS Task Force. Eur J Neurol.
et al. Conventional cancer screening versus PET/CT in dermatomyositis/polymyositis. Am J Med.