Dermatomyositis

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Image Type:  Dermatomyositis   

Body Site:  Skin 

Description 

It is an idiopathic inflammatory myopathy affecting both children and adults. It primarily involves the skin and muscles but can also impact joints, the esophagus, lungs, and, less commonly, the heart. Dystrophic calcinosis, often seen in children and adolescents, can complicate the condition. Cutaneous manifestations, such as lesions on the dorsal hands, are common.  

Signs and symptoms 

Persons with dermatomyositis often present with skin disease as one of the initial manifestations, and it may be the sole manifestation at onset in perhaps as many as 40% of individuals with this condition. Cutaneous involvement may manifest as follows:  

  • Eruptions predominantly occur in photo-exposed areas. 
  • Symptoms may include intense pruritus, mid-face erythema, eruptions along the eyelid margins with or without periorbital edema, and lesions over the knuckles. 
  • Other manifestations include nail fold changes, eruptions on the upper outer thighs, a scaly scalp, or diffuse hair loss. 

Muscle disease may occur concurrently, may precede the skin disease, or may follow the skin disease by weeks to years. Muscle involvement manifests as the following:  

  • Muscle disease may occur before, during, or after skin manifestations, ranging from weeks to years. 
  • Symptoms include proximal muscle weakness, fatigue during activities like climbing stairs, and muscle tenderness, though the latter is uncommon in dermatomyositis. 

Systemic manifestations  may include the following: 

  • General systemic disturbances, fever, arthralgia, malaise, weight loss, Raynaud phenomenon 
  • Dysphagia due to esophageal skeletal muscle involvement 
  • Gastroesophageal reflux due to esophageal smooth muscle involvement 
  • Dysphonia 
  • Atrioventricular defects, tachyarrhythmias, dilated cardiomyopathies 
  • Gastrointestinal ulcers and infections, more common in children 
  • Pulmonary involvement due to weakness of thoracic muscles, interstitial lung disease 
  • Subcutaneous calcification, which may result in contracture of joints, more common in children  
  • Children may also develop a tiptoe gait secondary to flexion contracture of the ankles in early childhood. 
  • Malignancy in adult patients. 

Diagnosis 

The following cutaneous and musculoskeletal examinations may assist in diagnosis: 

Cutaneous examination: 

  • Pathognomonic findings include heliotrope rash and Gottron papules. 
  • Non-specific features include malar erythema, violaceous erythema in a photosensitive distribution, and periungual changes. 
  • Rare manifestations like vesiculobullous erosive lesions and exfoliative erythroderma are more common in patients with associated malignancy. 

Muscle examination: 

  • Quadriparesis involving proximal musculature 
  • Difficulty rising from a seated or supine position without support 
  • Extensor muscles are often more affected than the flexor muscles 
  • Neck flexor muscle weakness 
  • Distal strength, sensation, and tendon reflexes maintained (unless the patient has severely weak and atrophic muscle) 

Testing 

Laboratory and other studies that may be helpful include the following: 

  • Muscle enzyme levels (eg, creatine kinase, aldolase, aspartate aminotransferase, lactic dehydrogenase) 
  • Myositis-specific antibodies 
  • Antinuclear antibody levels 
  • Pulmonary function studies with diffusion capacity 
  • Electrocardiography 
  • Esophageal manometry 
  • Colonoscopy to screen for underlying malignancy 
  • Papanicolaou smear in women for malignancy screening 
  • CA-125 and CA-19-9 for malignancy screening 

Imaging studies 

The following imaging studies may be used in the evaluation of dermatomyositis: 

  • MRI or ultrasonography of the muscles 
  • Chest radiography 
  • Barium swallow 
  • Electromyography 
  • Imaging to screen for underlying malignancy, including CT scanning of the chest, abdomen, and pelvis, as well as transvaginal ultrasound and mammography for women  

Procedures 

The following procedures may be helpful in the evaluation of dermatomyositis: 

  • Skin biopsy 
  • Muscle biopsy (open or via a needle): Findings can be diagnostic (perivascular and interfascicular inflammatory infiltrates with adjoining groups of muscle fiber degeneration/regeneration)  

Management 

Therapy for the muscle component of dermatomyositis involves the use of corticosteroids, typically with an immunosuppressive agent. Therapy for the skin disease includes the following, among other options:  

  • Sun avoidance 
  • Sunscreens and photoprotective clothing 
  • Topical corticosteroids 
  • Antimalarial agents 
  • Methotrexate 
  • Mycophenolate mofetil 
  • Immunoglobulins 

Pharmacotherapy 

Medications used in the management of dermatomyositis include the following: 

  • First-line treatment: Corticosteroids (e.g., prednisone) for muscle involvement. 
  • Immunosuppressive agents: Methotrexate, mycophenolate mofetil, azathioprine, rituximab, and sirolimus. 
  • Immunoglobulins: Intravenous or subcutaneous immunoglobulin. 
  • Antimalarials: Hydroxychloroquine or chloroquine. 
  • For calcinosis, options include diltiazem, colchicine, alendronate, and warfarin, with surgical excision considered for painful lesions. 

Non-pharmacotherapy 

General therapeutic measures may include the following: 

  • Physical therapy and rehabilitative measures 
  • Sun avoidance 
  • Sun protection (for example, broad-spectrum sunscreens, sun-protective clothing) 
  • Elevation of the head of the bed 
  • Avoidance of eating before bedtime 

Surgery 

Surgical care is usually unnecessary in the management of dermatomyositis. However, some patients may benefit from surgical removal of localized areas of calcinosis, particularly those that are painful. 

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