|Year : 2019 | Volume
| Issue : 1 | Page : 18-22
Dermatomyositis: A dermatological perspective
Deepthi Ravi1, Smitha Prabhu2
1 Consultant Dermatologist, Deepthi's Derma Care, Chennai, Tamil Nadu, India
2 Department of Dermatology and Venereology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
|Date of Web Publication||14-Feb-2019|
Department of Dermatology and Venereology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
Dermatomyositis (DM) is an autoimmune idiopathic inflammatory myopathy which has distinctive skin lesions, specific autoantibodies, and most importantly, symmetrical proximal muscle weakness and muscle inflammation of subacute onset. Some cases of DM present with only characteristic skin lesions without muscle disease and referred to as clinically amyopathic DM. Characteristic skin lesions include violaceous discoloration around the eyelids (heliotrope rash), erythematous rash over the face, erythematous scaly papules over the interphalangeal and metacarpophalangeal joints (Gottron's papules), erythema over the same joints (Gottron's sign), photosensitive pruritic erythema over the anterior chest and neck (V-sign), erythema extending to the shoulders and back (Shawl sign), distorted cuticles with dilated capillary loops over the proximal nail folds, and hyperkeratotic fissured skin over the palms and lateral aspect of the fingers (Mechanic's hands). Causes for mortality and morbidity in DM include malignancy, respiratory disease, and cardiac disease. After ruling out internal associations, Mangement involves photoprotection and medications including systemic corticosteroids, antimalarials, mycofenolate mofetil, biologicals and IV immunoglobulins, depending upon patient parameters.
Keywords: Cutaneous, dermatomyositis, management, myopathy
|How to cite this article:|
Ravi D, Prabhu S. Dermatomyositis: A dermatological perspective. Clin Dermatol Rev 2019;3:18-22
| Introduction|| |
Dermatomyositis (DM) is an autoimmune chronic disorder which has distinctive skin lesions, specific autoantibodies, and most importantly, symmetrical proximal muscle weakness and muscle inflammation of subacute onset. It is one of the idiopathic inflammatory myopathies. The most common age of onset of adult DM is in the fourth to sixth decade of the life, and the disease is more common in females.
In dermatomyositis there is microangiopathy in skin and muscles, with lysis of endomysial capillaries. Muscle ischemia occurs due to activation and deposition of complements. In a case of dermatomyositis, it is important to investigate the extent of muscle disease, in addition to other organ system involvement, and screening for underlying malignancy, wherever indicated. The most important causes of emergency and hence mortality in DM include malignancy, respiratory disease, and cardiac disease.
| Clinical Features|| |
The patient typically presents with symmetrical proximal muscle weakness with or without skin rash.
Muscle involvement presents with symptoms of difficulty in standing from a sitting position, climbing stairs, and doing overhead activities such as washing hair and combing. Involvement of the respiratory and esophageal muscles in severe cases may lead to dysphonia, dysphagia, dyspnea, and even respiratory failure.
Characteristic skin lesions include violaceous discoloration around the eyelids (heliotrope rash), erythematous rash over the face, erythematous scaly papules over the interphalangeal and metacarpophalangeal joints (Gottron's papules), erythema over the same joints (Gottron's sign), photosensitive pruritic erythema over the anterior chest and neck (V-sign), erythema extending to the shoulders and back (Shawl sign), distorted cuticles with dilated capillary loops over the proximal nail folds, and hyperkeratotic fissured skin over the palms and lateral aspect of the fingers (Mechanic's hands).,, In case of severe vasculitis, cutaneous ulcers can develop. Patchy or diffuse alopecia, panniculitis, and erythroderma can also occur. Calcinosis though a rare feature in adult DM is seen in 30% of cases of juvenile DM.
Some cases of DM present with only characteristic skin lesions without muscle disease and referred to as clinically amyopathic DM (CADM). The patient may present with constitutional symptoms such as night sweats, fever, fatigue, and weight loss. Other presenting features are arthralgia or arthritis, myalgia, and Raynaud's phenomenon.
Interstitial lung disease (ILD) is seen in one-third to half of the patients with DM and increases the morbidity and risk of mortality. The spectrum of ILD ranges from asymptomatic basal fibrosis characterized by dyspnea and cough to chronic respiratory failure needing lifelong respiratory support and adult respiratory distress syndrome. Aspiration pneumonitis, pneumomediastinum, and pneumothorax may also be seen. Chronic inflammation of cardiac muscles and atherosclerosis can lead to pericarditis, myocarditis, conduction abnormalities, myocardial infarction, and subsequently heart failure.
Around one-third of the patient with DM have an associated malignancy. The most common is ovarian malignancy, which is followed by lung, gastrointestinal, breast, and non-Hodgkin's lymphoma.
DM can have overlapping features with mixed connective tissue disorder and systemic sclerosis.
| Management|| |
Basic investigations: In suspected cases of DM, a complete blood count with erythrocyte sedimentation rate (ESR), routine urine tests, full biochemical profile, rheumatoid factor, inflammatory markers, chest X-ray, and fecal occult blood is suggested.
Half of the patients have raised ESR and one-fifth of the patients have rheumatoid factor positive, especially those with overlap syndrome.
The level of urine creatine excretion can be done to assess the state of myositis though it is increased in steroid myopathy. Elevation of serum myoglobin levels is also seen in DM.
Creatinine kinase (CK) is the most sensitive enzymes and can be elevated up to 50 times. If there is no physical damage to the muscle, it is also highly specific for DM. However, lactate dehydrogenase, aspartate transaminase, alanine transaminase, and aldolase can also be elevated.
The muscle strength improves and the muscle enzyme levels usually come down, but the vice-versa is not true. Therefore, response to therapy should be assessed with the improvement in muscle strength rather than with reduction in CK levels.
Electromyography (EMG) is not much useful to confirm the diagnosis of DM. However, a myopathic pattern with multiple, short duration, small amplitude motor unit action potentials,,,, if present, can indicate the site of active muscle involvement, thus aiding in selection of muscle biopsy site.
An open muscle biopsy is taken from the site of maximal muscle weakness or tenderness or indicated by maximum changes on EMG. Perifascicular or interfascicular inflammation is seen in DM. Endothelial hyperplasia and thus obliteration of the capillaries is seen in the intramuscular blood vessels. Necrosis and phagocytosis of the muscle fibers are seen visible as microinfarcts and cause perifascicular atrophy which is the diagnosis of DM.,
Magnetic resonance imaging
Magnetic resonance imaging (MRI) of the proximal muscles may show edema which can help to assess the extent of muscle disease as well as to guide the muscle biopsy site.
Skin biopsy is usually considered in amyopathic DM, and it shows perivascular inflammatory infiltrate with lymphocytic infiltration at the dermoepidermal junction. It is difficult to distinguish from SLE.
| Autoantibodies|| |
Antinuclear antibodies (ANAs) are positive in around 80% of DM patients and are not of much diagnostic or prognostic significance. Many antibodies in DM are cytoplasmic and will not cause a positive ANA.
Myositis-specific antibodies help to define the phenotype of DM and are separated in three groups, namely antisynthetase antibodies, which is the most common followed by antisignal recognition particle (SRP) antibodies and anti-Mi2 antibodies.
The most common antisynthetase antibody is anti-Jo1, the others being anti-PL12, anti-PL7, anti-EJ, anti-OJ, anti-HA, anti-KS, and anti-ZO. Positivity to these is referred to as antisynthetase syndrome and is characterized by the Raynaud's syndrome, ILD, mechanic's hands, fever, and arthritis. Those with anti-SRP antibodies have severe, acute resistant DM with cardiac involvement, acute necrotizing myopathy, and rare cutaneous features. Anti-Mi2 antibody positivity is highly specific for DM, and these patients have classic cutaneous features, significant cuticular changes, lower risk of myopathy, and good response to treatment.
Clinically, significant novel antibodies have been described in [Table 1]. The presence of myositis associated antibodies such as anti-PM/Scl, anti-Ro, anti-U1RNP, anti-Ku, and anti-La may help to detect the presence of an overlapping connective tissue disorder.
| Tests to Rule Out Other Organ Involvement and Malignancy|| |
Pulmonary function tests along with high-resolution computed tomography are needed to investigate ILD, which is an important cause of mortality in DM. A restrictive pattern is seen on PFT which can also be seen in respiratory muscle weakness. Bronchoscopy and bronchoalveolar lavage can be done to rule out drug hypersensitivity and infection and nonresponse to treatment in ILD and malignancy. Lung biopsy can be done to rule out malignancy or infection and can determine the response of ILD to treatment.
A baseline ECG helps to screen for cardiac involvement such as conduction defects, ST-T changes, and arrhythmias. An echocardiogram and cardiac MRI can help to detect the sites of myocardial inflammation.
Esophageal involvement can be assessed by means of barium swallow, esophageal manometry, and esophagogastroscopy. Nailfold capillaroscopy can help to assess response to the treatment.
The risk of malignancy increases with increased severity of skin disease, diaphragmatic weakness, dysphagia, and the absence of extramuscular systemic features such as ILD. Computed tomography scans of the abdomen, pelvis, thorax, and neck may be needed in all adult patients. If there is high suspicion for malignancy, a positron-emission tomography can be performed.
Calcinosis is another complication seen more in juvenile DM, with increased duration of the disease, and can be detected with plain radiography.
The diagnosis of DM can be done with the help of Bohan and Peter criteria, which are given in [Box 1].
| Treatment|| |
Dermatomyositis, especially in pediatric age group, is almost fully amenable to treatment, though some patients have long term or lifelong residual symptoms, necessitating prolonged immunosuppression. Aggressive treatment in the early stages can help to reduce the incidence of myopathy and calcinosis.
Photoprotection by the avoidance of peak-hour sun exposure and use of sunscreens and protective clothing helps to prevent exacerbation of skin lesions in DM. Bed rest is recommended in the acute stages of the disease. After the active phase of the disease has subsided, physical therapy is required for rehabilitation. Cutaneous DM Disease Area and Severity Index is a tool which helps to assess the cutaneous disease activity score and has a score range from 0 to 100, and it has been quite effective as a prognostic tool according to a study done by Anyanwu et al.
In patients of cutaneous DM sun protection, antimalarial agents, topical steroids, and antihistamines are the first-line therapies. Second-line therapy includes oral corticosteroids which can be later tapered and other immunosuppressive agents such as methotrexate, mycophenolate mofetil, and azathioprine. Patients who are not responding to these agents can be given intravenous immunoglobulins (IVIgs). Rituximab is the next line of therapy.
Oral tacrolimus and sirolimus have been helpful in the improvement of myopathy.
Thalidomide, dapsone, and oral calcineurin inhibitors have also been used. Therapies such as plasmapheresis, total-body irradiation, and stem cell transplantation have also been used in patients with refractory CADM.
Patients with mainly skin involvement can be started on hydroxychloroquine (HCQ) at a dose of 6.5 mg/kg/day or less for a duration of 2 months. HCQ can also be combined with mepacrine with the good results in CADM. If it is ineffective, quinacrine at a dose of 100 mg/day can be introduced. In patients who had a reaction or were not responsive to HCQ, chloroquine in a dose of 3.5 mg/kg/day or less can be used.
| Corticosteroids|| |
Systemic corticosteroids are the first line of treatment when there are both cutaneous and muscle involvements, only muscle involvement, extensive skin disease, or when the patient is not responding to antimalarial agents for more than 2 months. If the muscle disease is life threatening or if oral prednisolone is not effective, pulse therapy of IV methylprednisolone in a dose of 0.5–1 g/day can be given for 3 subsequent days followed by oral prednisolone in a dose of 0.5–1 mg/kg/day. Even potent topical steroids have not shown much benefit in CADM, however, topical tacrolimus (0.1%) has been quite effective.
The muscle rash and weakness start improving within 1 or 2 weeks of introduction of systemic corticosteroids. Since DM is a chronic disease, systemic steroids need to be given for a long period of time. Because of the side effects of long-term steroid therapy, the goal of treatment is to taper the dose and ultimately stop steroids. The patients are then shifted to other immunosuppressive agents.
Patients of DM may have significant pruritus, and topical agents such as camphor, pramoxine, lidocaine, and menthol as well as oral antihistamines and amitriptyline can be given.
[TAG:2]Other Immunosuppressive Agents[/TAG:2]
Following 3 weeks to a month of treatment, oral steroids are slowly tapered, and other immunomodulators are added to prevent steroid-related toxicity.
In DM, methotrexate is considered to be the first-line steroid-sparing agent. It is given in a dose of 7.5 to a maximum of 25 mg/week either orally or subcutaneously. Since it takes 6–8 weeks to show effect, it is not useful for rapid control of acute or progressive DM. Hepatic and pulmonary parameters should be monitored.
Azathioprine is given in a dose of 2–3 mg/kg/day and shows benefits on long-term follow-up data in reducing the dose of steroids.
Cyclosporine in a dose of 3–5 mg/kg/day is useful in refractory cases and has been used in combination with IVIg for relapsed or resistant disease. Common side effects include hypertension, infection, and renal toxicity.
Mycophenolate mofetil in a dose of 500–1500 mg/day has also been found to be effective in patients, who are resistant or intolerant to other immunosuppressants, and also been used in combination with IVIg in severe myositis cases. Monitoring for hepatic and hematological toxicities should be done.
IVIg at a dose 2 g/kg given for 2–5 days every month for 3 months can be given if there is no response to antimalarial drugs and other immunosuppressants. It is useful in refractory myositis, especially in patients with dysphagia. The cost is a limiting factor in this treatment.
Rituximab administered in a dose of 1 g for 2 weeks apart has been effective in recalcitrant or severe disease.
The anti-inflammatory effects of dapsone may be useful in resistant cutaneous DM. Antiestrogens such as tamoxifen and anastrozole are useful in the improvement of skin lesions though there is relapse on withdrawal. Pulsed dye laser is useful in reducing the poikilodermatous erythema in DM. Efalizumab, which is a monoclonal antibody against CD11a, is useful in the reduction of erythema over the exposed areas. Leflunomide in a dose of 20 mg/day has been effective in the treatment of recalcitrant skin lesions of DM.
Juvenile DM is treated with the same medications as adults. A combination of corticosteroids with weekly methotrexate is the mainstay of therapy.
Creatine supplements along with exercise have shown a significant functional improvement of muscles. Renal toxicity should be kept in mind, and it cannot be given in individuals having any serious underlying medical condition and preexisting renal disease.
Patients of myositis, even those who are responding to treatment, have a chance of developing a disability. An exercise regimen is required for all patients of myositis. In acute phases, exercises are to be avoided except to maintain the range of movement and to prevent pressure sores and hypostatic pneumonia. However, in a stable patient, exercise is required for muscle function and endurance. It also helps to reduce the expression of pro-inflammatory and profibrotic factors and helps in the movement toward oxidative metabolism thus reducing muscle inflammation and fibrosis.
A multifaceted approach to treatment is necessary for DM depending on the skin, muscle, lung involvement as well other organ involvement, comorbidities, and possible side effects of medication. Dermatologists and rheumatologists need to work in tandem for the treatment of DM. Inputs from respiratory medicine specialists and other specialties may also be needed.
Systemic corticosteroids are the main therapy with immunosuppressants such as methotrexate, cyclosporine, and azathioprine used for long-term therapy to reduce the side effects of steroids and IVIg useful for acute DM. A summary of the approach to a suspected case of DM is given in [Chart 1].
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