Dermatomyositis

Last reviewed: February 2019

Last updated: May 2018

Summary

An idiopathic inflammatory myopathy characterized by the presence of hallmark cutaneous lesions (e.g., heliotrope rash, Gottron papules).

Skin lesions are frequently the initial presenting complaint, with muscle involvement developing later.

Some patients have cutaneous involvement alone.

May be associated with interstitial lung disease, cardiac involvement, esophageal involvement, and underlying malignancy.

Initial treatment of muscle disease is with high-dose oral corticosteroids (prednisone), followed by the addition of immunosuppressants and intravenous immunoglobulin in refractory cases.

Skin manifestations are treated with topical antipruritics and topical corticosteroids. Antimalarials, topical tacrolimus, immunosuppressants, and intravenous immunoglobulin are generally used for resistant or severe skin disease. Photoprotection is advised in all patients.

Definition

Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by skin manifestations. Diagnosis is based on the presence of a symmetric proximal myopathy, elevated muscle enzymes, myopathic changes on electromyography, a characteristic muscle biopsy, and a typical skin rash (e.g., periorbital dusky violaceous erythema, or macular violaceous erythema such as in V, shawl, and Gottron signs). [1] Some patients present with typical cutaneous manifestations but have delayed-onset, subclinical, or absent muscle disease. [2] DM occurs in both adult and juvenile forms and can overlap with other connective tissue disorders (scleroderma, systemic lupus erythematosus, mixed connective tissue disease, and, less often, rheumatoid arthritis and Sjogren syndrome). [3] It may be associated with interstitial lung disease, cardiac involvement, esophageal involvement, and underlying malignancy. Adult-onset DM is significantly associated with occult malignancy. [4]

History and exam

Key diagnostic factors

Gottron papules
heliotrope rash with or without periorbital edema
macular violaceous erythema
periungual erythema, nail-fold capillary dilation, cuticular overgrowth
"mechanic's" hands
proximal muscle weakness

Full details

Other diagnostic factors

photosensitivity
poikiloderma vasculare atrophicans
pruritus
fatigue and malaise
dyspnea
weight loss
fever
myalgia
arthralgia
dysphagia
palpitations and syncope
Raynaud phenomenon
cutaneous calcinosis
erythroderma
vesicobullous lesions
leukocytoclastic vasculitis
cutaneous necrosis
nonscarring alopecia

Full details

Risk factors

genetic predisposition
bimodal age distribution: children and age >40 years
female gender
black race
ultraviolet radiation
infectious agents
drugs
immunization

Full details

Diagnostic investigations

1st investigations to order

serum creatine kinase (CK)
serum aldolase
muscle biopsy
electromyogram (EMG)
skin biopsy
antinuclear antibody (ANA)

Full details

Investigations to consider

myositis-specific antibodies (MSAs)
muscle MRI
ECG
echocardiography
cardiac troponin I
chest x-ray (CXR)
pulmonary function tests (PFTs)
high-resolution CT of chest
barium swallow or videofluoroscopic assessment of swallow

Full details

Treatment algorithm

ACUTE

severe disease or acute flares

ONGOING

combined muscle and skin disease

skin disease only

Contributors

Authors VIEW ALL 

Sarah A. Saunders, MRCP, MBChB

Consultant Physician and Rheumatologist

Department of Rheumatology

Centre for Rheumatic Diseases

Glasgow Royal Infirmary

Glasgow

Disclosures

SAS declares that she has no competing interests.

Rajan Madhok, MD, FRCP(Glasg)

Consultant Physician and Rheumatologist

Department of Rheumatology

Glasgow Royal Infirmary

Glasgow

Disclosures

RM holds shares in GSK to the value less than £12,000.

Acknowledgements

Dr Sarah A. Saunders and Dr Rajan Madhok would like to gratefully acknowledge Dr Nicola Alcorn, a previous contributor to this monograph. NA declares she has no competing interests.

Peer reviewers VIEW ALL 

Nizar Souayah, MD

Assistant Professor of Neurology

Director of EMG Laboratory & Peripheral Neuropathy Center

Department of Neurology & Neurosciences

New Jersey Medical School

Newark

Disclosures

NS declares that he has no competing interests.

Sami Khella, MD

Physician

Department of Neurology

Penn Presbyterian Medical Center

University of Pennsylvania Health System

Philadelphia

Disclosures

SK declares that he has no competing interests.

Yusuf Yazici, MD

Assistant Professor

Associate Director

Arthritis Program

Director

Behcet's Syndrome Center

Seligman Center for Advanced Therapeutics

New York University Hospital for Joint Diseases

New York

Disclosures

YY has served as a consultant for Bristol-Myers Squibb, Roche, Celgene, Centocor, and UCB, and has been a speaker for Pfizer and Bristol-Myers Squibb.

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Dermatomyositis

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

severe disease or acute flares

combined muscle and skin disease

skin disease only

Contributors

Authors VIEW ALL 

Sarah A. Saunders, MRCP, MBChB

Disclosures

Rajan Madhok, MD, FRCP(Glasg)

Disclosures

Acknowledgements

Peer reviewers VIEW ALL 

Nizar Souayah, MD

Disclosures

Sami Khella, MD

Disclosures

Yusuf Yazici, MD

Disclosures

Differentials

Guidelines

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