II. Epidemiology

  1. Twice as common in women
  2. Mean age at diagnosis
    1. Adults: 40 years
    2. Children: 4 to 14 years, peaking at ages 4-10 years (juvenile Dermatomyositis)

III. Pathophysiology

  1. Group 2 of Polymyositis disorders (accounts for 25%)
  2. Classification
    1. Without Muscle Weakness (amyopathic Dermatomyositis)
    2. With Muscle Weakness
      1. Pediatric Dermatomyositis
      2. Adult Dermatomyositis (with or without cancer)

IV. Signs: Pathognomonic for Dermatomyositis

  1. Gottron's Papules (33% to 70% of patients)
    1. Violaceous (purple) flat topped Papules
    2. Distribution
      1. Dorsal interphalangeal joints of hand
      2. Dorsal metacarpophalangeal joints
      3. Knees
      4. Elbows
      5. Medial malleoli
  2. Gottron's Sign
    1. Symmetric erythematous or violaceous (purple) Plaques
      1. Smooth and usually non-Scaling
      2. Edema is variably present
    2. Distribution
      1. Same as Gottron's Papules
      2. Extends over extensor tendons on hands and Forearms
      3. Spares interphalangeal spaces (unlike SLE)

V. Signs: Characteristic Findings

  1. Facial photosensitivity and dusky erythema on face
    1. Classic lilac-colored (heliotrope) rash
    2. Occurs in 30 to 60% of patients early in disease
    3. Distribution
      1. Eyelids and periorbital area
      2. Bridge of nose
      3. Malar area
  2. Erythematous, poikilodermatous Macules
    1. V-area of neck (V-sign)
    2. Shoulders and upper back (Shawl sign)
  3. Periungual Vasculitis
    1. Vertical Telangiectases involve cuticles
  4. Mechanic's hand
    1. Fissured, scaly, hyperkeratotic, hyperpigmented hands

VI. Signs: Other Findings

  1. Poikiloderma atrophicans vasculare
    1. Circumscribed violaceous erythema
    2. Occurs late in Dermatomyositis
    3. Associated findings
      1. Central atrophy
      2. Telangiectasia
      3. Hypopigmentation
    4. Distribution
      1. Posterior Shoulders, back and buttocks
      2. V-shaped area of anterior neck and chest
  2. Calcinosis cutis
    1. Idiopathic subcutaneous Calcium deposits
    2. Occurs in 30-70% of children and 10% of adults
    3. Distribution
      1. Buttocks
      2. Elbows
      3. Knees
      4. Areas of local Trauma

VII. Associated Systemic Signs and Conditions

  1. See Polymyositis
  2. Proximal Muscle Weakness
    1. Gowers' Sign
      1. Uses arms to raise self
    2. Trendelenburg's Sign
      1. Weakness of raised leg in one legged standing
  3. Common Systemic Associations
    1. Dysphonia
    2. Dysphagia
  4. Less common systemic associations
    1. Respiratory Muscle Weakness
    2. Visual changes
    3. Abdominal Pain
  5. Malignancy (only seen in adult Dermatomyositis)
    1. Highest risk over age 45 years
    2. Most commonly associated cancers
      1. Ovarian Cancer
      2. Gastric Cancer
      3. Lymphoma
    3. Less commonly associated cancers
      1. Lung Cancer
      2. Cancer of male genitalia
      3. Skin cancer (Melanoma and non-Melanoma)
      4. Kaposi's Sarcoma
      5. Mycosis Fungoides

VIII. Subtypes

  1. Juvenile Dermatomyositis findings
    1. Low-grade fever
      1. High fever with rash and profound Muscle Weakness in acute onset (25% of cases)
    2. Gastrointestinal symptoms
    3. Symmetric Arthritis of large and small joints
    4. Cardiac conduction delay
    5. Truncal and proximal Muscle Weakness (may use Gower's Sign)
    6. No malignancy association
  2. Overlap Syndrome (comorbid Connective Tissue Disease)
    1. Rheumatoid Arthritis
    2. Scleroderma
    3. Systemic Lupus Erythematosus
    4. Sjogren's Syndrome
    5. Polyarteritis Nodosa
    6. Mixed Connective Tissue Disease
  3. Amyopathic Dermatomyositis (2-11%)
    1. Pathognomonic skin changes without Myositis
    2. Presenting symptoms
      1. Lethargy or Fatigue
      2. Pruritus
      3. Photosensitivity
      4. Arthralgias

IX. Differential Diagnosis

X. Radiology

XI. Labs: Initial Evaluation

  1. Myositis Labs
    1. Alanine Aminotransferase (ALT)
    2. Aspartate Aminotransferase (AST)
    3. Lactate Dehydrogenase (LDH)
    4. Creatine Phosphokinase (CPK)
    5. Aldolase (consider)
  2. Urinalysis for creatinuria or Myoglobinuria
  3. Sedimentation rate (ESR) elevated
  4. Complete Blood Count (CBC) identifies Anemia
  5. Antinuclear Antibody (ANA)
  6. Serum chemistry panel
  7. Stool Guaiac

XII. Labs: Secondary Evaluation

  1. See Dermatomyositis Evaluation
  2. Electromyogram (EMG) shows myopathic pattern
  3. Consider biopsy
    1. Muscle biopsy
    2. Skin biopsy (to rule-out other causes)

XIII. Management

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Related Studies

Ontology: Dermatomyositis (C0011633)

Definition (CHV) an inflammatory muscle disease accompanied by muscle weakness and skin rash
Definition (CHV) an inflammatory muscle disease accompanied by muscle weakness and skin rash
Definition (CHV) an inflammatory muscle disease accompanied by muscle weakness and skin rash
Definition (MSH) A subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. The illness occurs with approximately equal frequency in children and adults. The skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. The disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. The childhood form of this disease tends to evolve into a systemic vasculitis. Dermatomyositis may occur in association with malignant neoplasms. (From Adams et al., Principles of Neurology, 6th ed, pp1405-6)
Definition (CSP) progressive condition characterized by symmetric proximal muscular weakness with elevated serum levels of muscle enzymes and a skin rash, typically a purplish-red erythema on the face, and edema of the eyelids and periorbital tissue; affected muscle tissue shows degeneration of fibers with a chronic inflammatory reaction; occurs in children and adults, and in the latter may be associated with visceral cancer or other disorders of connective tissue.
Concepts Disease or Syndrome (T047)
MSH D003882
ICD9 710.3
ICD10 M33 , M33.9, M33.90
SnomedCT 203795006, 38826005, 156456005, 201448000, 201445002, 396230008
English Dermatomyositides, Dermatomyositis, Dermatopolymyositis, Dermatopolymyositis, unspec, Dermatopolymyositis, unspecified, POLYMYOSITIS/DERMATOMYOSITIS, [X]Dermatopolymyositis, unspec, [X]Dermatopolymyositis, unspecified, POLYMYOSITIS DERMATOMYOSITIS, Polymyositis Dermatomyositis, Polymyositis-Dermatomyositides, Polymyositis-Dermatomyositis, Dermatopolymyositides, Dermatopolymyositis, unspecified, organ involvement unspecified, Dermatomyositis [Disease/Finding], dermatomyositis, dermatomyositides, Dermatopolymyositis, unsp, organ involvement unspecified, dermatopolymyositis (diagnosis), [X]Dermatopolymyositis, unspecified (disorder), DERMATOMYOSITIS, Wagner-Unverricht syndrome, Polymyositis with skin involvement, DM - Dermatomyositis, Dermatomyositis (disorder), dermatopolymyositis, polymyositis; with involvement of skin, dermatomucosomyositis
French DERMATOMYOSITE, Dermatomyosite, Polymyosite-Dermatomyosite
Portuguese DERMATOMIOSITE, Dermatomiosite, Polimiosite-Dermatomiosite
Spanish DERMATOMIOSITIS, síndrome de Wagner - Unverricht, polimiositis con compromiso de piel, [X]dermatopolimiositis, no especificada, [X]dermatopolimiositis, no especificada (trastorno), dermatomiositis (trastorno), dermatomiositis, Dermatomiositis, Polimiositis-Dermatomiositis
German DERMATOMYOSITIS, Dermatomyositis-Polymyositis, nicht naeher bezeichnet, Dermatomyositis-Polymyositis, Dermatomyositis, Polymyositis-Dermatomyositis, Dermatopolymyositis
Swedish Dermatomyosit
Japanese ヒフキンエン, 筋炎-皮膚, 皮膚筋炎
Czech dermatomyozitida, Dermatomyozitida, polymyozitida - dermatomyozitida, dermatopolymyozitida
Finnish Dermatomyosiitti
Italian Polimiosite-dermatomiosite, Dermatopolimiosite, Dermatomiosite
Korean 상세불명의 피부다발성근육염, 피부다발근육염
Polish Zapalenie skórno-mięśniowe
Hungarian Dermatomyositis
Norwegian Dermatomyositt
Dutch polymyositis; met huidaandoening, Dermatopolymyositis, niet gespecificeerd, dermatomyositis, Dermatomyositis, Dermatopolymyositis, Polymyositis-dermatomyositis

Ontology: Gottron's papules (C0423781)

Concepts Finding (T033)
ICD10 L94.4
SnomedCT 247455006, 201084000
Dutch Gottron-papellen, Gottron; papel, papel; Gottron, Papula van Gottron
French Papules de Gottron
German Gottron-Papeln
Italian Papule di Gottron
Portuguese Pápulas de Gottron
Spanish Pápulas de Gottron, pápulas de Gottron (hallazgo), pápulas de Gottron
Japanese ゴットロン丘疹, ゴットロンキュウシン
Czech Gottronovy papuly
Korean 고트론 구진
English Gottron papules, gottron's papules, gottron's papule, gottron's papules (diagnosis), Gottron's papules (disorder), Gottron's papules, Gottron's papules (finding), Gottron; papule, papule; Gottron
Hungarian Gottron-papulák

Ontology: Idiopathic dermatomyositis (C0554592)

Concepts Disease or Syndrome (T047)
SnomedCT 281358000
English Idiopathic dermatomyositis, Idiopathic dermatomyositis (disorder)
Spanish dermatomiositis idiopática (trastorno), dermatomiositis idiopática