Juvenile Dermatomyositis
Myra Lalas Pitt
9/26/11
Definition
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Systemic inflammatory and noninflammatory
vasculopathy likely due to a combination of genetic
& environmental factors
The most common pediatric inflammatory
myopathy (85%)
Bimodal age distribution (ages 5–9 yr and 10–14 yr)
Incidence 0.5/100,000
♀:♂ ratio 2:1
Predominance in Caucasian > Hispanics and AfricanAmerican children in the US
Signs and Symptoms
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Symmetrical and
progressive proximal
muscle weakness (±
dysphagia and
respiratory
involvement)
Calcinosis
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Heliotrope rash
Scaly and erythematous
dermatitis over the
dorsum of the hands
(Gottron's sign);
involvement of the
knees, elbows, medial
malleoli, face, neck, and
upper torso;
Nonpalpable macular
rash
Heliotrope rash
Gottron Papule
Calcinosis
Periungual Capillary Changes
Seen in over 90% of patients with juvenile
dermatomyositis, include dilated, tortuous
capillaries and areas of capillary loss along the
nailfold
Diagnosis
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In 1975, Bohan and Peter proposed a diagnostic criteria for JDM:
Symmetrical weakness of the proximal muscles
Characteristic cutaneous changes, consisting of heliotrope
dermatitis (reddish-purple rash on the upper eyelids with
periorbital edema) and Gottron's papules (erythematous,
papulosquamous eruption over the dorsal surfaces of the
knuckles)
Elevation of the serum level of one of the muscle enzymes
Electromyography (EMG) demonstrating denervation and
myopathy
Muscle biopsy displaying necrosis and inflammation
Differential Diagnosis
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Inherited muscular
dystrophies
Metabolic
abnormalities
(Hypokalemia,
hypocalcemia,
hypercalcemia,
uremia)
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Mitochondrial
myopathies
Endocrine:
Hypothyroidism,
hyperthyroidism
Cushing
syndrome/exogenous
steroid myopathy
Diabetes mellitus
Neurologic disorders:
Myasthenia gravis
Guillain-Barre syndrome
Multiple sclerosis
•
Infections:
Viral
Lyme disease
Parasitic (Trichinosis,
toxoplasmosis, filariasis,
trypanosoma,
cysticercosis)
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Autoimmune
SLE
JIA
PAN
Crohn
UC
Celiac disease
Psoriasis
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Treatment
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Aims:
suppress the inflammatory response
prevention loss of muscle function
maintain joint range of motion
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1st line: Corticosteroids
May add: methotrexate, cyclosporine, and,
in severe cases, cyclophosphamide
Hydroxychloroquine and IVIG are
particularly helpful in managing the skin
manifestations.
Sun protection
PT/ OT
Prep Question
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A 16-year-old boy presents with diffuse muscle
pain and dark urine after a summer football
practice. On physical examination, he appears
uncomfortable, and his arm and leg muscles
are painful to palpation.
Of the following, the MOST likely cause of this
boy's findings is
A.
B.
C.
D.
E.
Bacterial abscess of the quadriceps
Genetic mitochondrial disorder
Inflammatory dermatomyositis
Limb girdle muscular dystrophy
Myositis due to influenza
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First, the event occurred after a football practice, where
exercise often is extreme. Some rare mitochondrial
conditions affecting energy metabolism tend to present
in precisely this setting.
Second, there is the darkening of the urine.
Myoglobinuria indicates rhabdomyolysis or breakdown
of muscle fibers. Accordingly, the adolescent in the
vignette most likely has a genetic disorder affecting
mitochondrial function (carnitine palmitoyl transferase
II deficiency).
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A bacterial abscess of the quadriceps would not produce diffuse
pain of the arms and legs.
Inflammatory dermatomyositis presents with proximal
weakness, pain, and characteristic skin findings.
Neither dermatomyositis nor limb girdle muscular dystrophy
presents acutely with rhabdomyolysis.
Influenza can present with myositis, but this adolescent has
been at summer football practice and had no signs of systemic
illness prior to this dramatic presentation.
References
Lowry AW, Bhakta KY, Nag PK, "Chapter 26. Rheumatology" (Chapter).
Lowry AW, Bhakta KY, Nag PK: Texas Children's Hospital Handbook of
Pediatrics and Neonatology:
http://www.accesspediatrics.com/content/7448943.
Rider Lisa G, "Chapter 205. Juvenile Dermatomyositis" (Chapter). Colin
D. Rudolph, Abraham M. Rudolph, George E. Lister, Lewis R. First, Anne A.
Gershon: Rudolph's Pediatrics, 22e:
http://www.accesspediatrics.com/content/7019537.
Soep Jennifer B, "Chapter 27. Rheumatic Diseases" (Chapter). William W. Hay, Jr.,
Myron J. Levin, Judith M. Sondheimer, Robin R. Deterding: CURRENT Diagnosis &
Treatment: Pediatrics, 20e: http://www.accesspediatrics.com/content/6586500.
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