Overview of Juvenile
Dermatomyositis
Pediatric Rheumatology
Red Team Resident
Teaching Series
What is Juvenile Dermatomyositis?
“A multisystem disease of uncertain origin that results in chronic
inflammation of striated muscle and skin.” (Cassidy and Petty, 2011)
• A rare pediatric autoimmune disease, but the most common
inflammatory myopathy in children
• Average annual incidence rate: 3.2 cases per 1 million children
(Mendez, EP, et al. 2003)
• 16-20% of all dermatomyositis patients have onset in childhood
• Girls > boys (2.2:1)
• Peak age of onset: 7.6 years old, peak range: 5-14 years of age
• No difference in incidence in different ethnicities
What is Juvenile Dermatomyositis?
• Systemic small vessel vasculopathy
• Mainly muscle and skin involvement, but can involve other
organ systems
• Presentation: insidious onset malaise, fever, fatigue, rash,
muscle weakness/pain
• Don’t always have skin AND muscle manifestations at the same
time
• Amyopathic JDM = JDM without evidence of muscle involvement
Differential Diagnosis of Juvenile
Idiopathic Inflammatory Myopathies
Feldman et al, Lancet 2008; 371, 2201-12
JDM - Etiology & Pathogenesis
• Cause unknown
• Likely autoimmune angiopathy
• Environmental and genetic factors implicated
• A history of infection prior to onset is common
• 65- 70% of patients have a history of a significant infection
during the three months prior to first onset of symptoms
• Proposed triggers include various infectious agents, vaccines,
medications, UV light
• Cellular and humoral immunity implicated
• Complement-mediated injury important
• Innate immune response: type I interferons and dendritic
cells
Cellular and Humoral Immunity
• Autoimmunity
• ~70-80% JDM patients have positive ANA
• ~10% children have classic myositis specific antibodies (MSA)
compared to >50% adults
• Some auto-antibodies that you might see positive in these
patients: anti-Jo1, anti-SSA, anti-SSB, anti-topoisomerase, antiU1RNP
• Abnormalities of cell-mediated immunity
• MHC class I antigens strongly expressed by muscle cells of JDM
patients but not normal controls
• Association with immunodeficiency
• Occurrence in children with hypogammaglobulinemia,
selective IgA deficiency, & C2 deficiency
Clinical Features of JDM Patients
• Constitutional
• Fever: 16-65%
• Adenopathy: 20%
• Lethargy: 10%
• Musculoskeletal
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Weakness: 95%
Myalgia or arthralgia: 25-73%
Arthritis: 23-58%
Contractures: 26-27%
Raynaud’s disease: 9-14%
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Gottron’s papules: 57-100%
Heliotrope rash: 66-100%
Nailfold capillary changes: 91%
Malar or facial rash: 42-73%
Mouth ulcers: 35%
Skin ulcers: 23-30%
Limb edema: 11-32%
Calcinosis: 6-30%
Lipodystrophy: 10-14%
• Cutaneous
• Pulmonary
• Dyspnea: 7-43%
• Gastrointestinal
• Dysphonia or dysphagia: 18-44%
• Gastrointestinal symptoms: 22-37%
Feldman et al, Lancet 2008; 371, 2201-12
Dermatomyositis – other organ
involvement
• Gastrointestinal vasculitis- gut wall perforation
• Arthritis - common but usually early and mild, nonerosive
• Cardiac - inflammation, fibrosis, conduction defects
• Renal - glomerular hypercellularity
• Pulmonary - fibrosis, pneumothorax
• Central nervous system - behavior changes, seizures
• Alopecia
• Eyes - exudative vasculitis of retina
• Derm – calcinosis, subcutaneous nodules, ulcerations
• Lipodystrophy
The Pictures of Juvenile
Dermatomyositis
Heliotrope Rash
with periorbital
edema
V Sign
Gottron’s Papules
Shawl Sign
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Malar rash
Rash on extensor
surfaces
Calcinoses
Heliotrope: The flower for which
the rash is named!
Periorbital edema and heliotrope
rash
The heliotrope rash occur over the upper eyelids and is violaceous, reddishpurple in coloration (see last slide). It is often associated with periorbital
edema, and is often accompanied by a malar rash (see next slide). It is one
of the most common rashes seen in JDM.
Facial and extremity rash
The facial rash of JDM appears in a malar-distribution (bilateral cheeks,
extending across the nasal bridge, sparing the nasolabial folds), similar to the
malar rash seen in lupus but usually less well-demarcated. The chin and
forehead can also be involved. This tends to be a photosensitive rash. This
patient also has rash on her bilateral elbows, consistent with Gottron’s papules
(see next slide).
Gottron’s papules
Gottron’s papules are shiny, erythematous, scaly plaques seen in a
symmetrical distribution on the extensor surfaces of the upper and lower
extremities (often over the MCPs, PIPs, and DIPs of the hands, also occur on
the elbows, knees, and sometimes on the malleoli of the ankles). They can
start initially as flat erythematous lesions. It is one of the most common rashes
seen in JDM. Note also the erythema around the nailbeds, reflecting nailbed
capillary abnormalities, another common finding (see next slide).
Nailbed Capillary Abnormalities
A common finding in JDM, this reflects active vasculitis of the nailbed
capillaries. Upper left, a normal nailfold capillary pattern. Upper right, shows
dilation of capillary loops, with loss of surrounding loop structures (“dropout”). Lower right, dilated capillary loops are present with areas of arborized
clusters of loops. Lower left, dilated and prominent capillary loops.
Other Skin Manifestations
• Photosensitive rash can also occur on the chest, neck, extremities, scalp (this is
the V-sign and shawl sign seen on Slide #7)
• May evolve into poikiloderma (hyper or hypopigmentation with atrophy and
telangiectasia)
• Mechanic’s hands
• Pruritis, psoriasiform scalp dermatitis
Poikiloderma: Confluent
violaceous papules with mottled
dyspigmentation and
telangiectasias
Mechanic’s hands: Scaly, fissured,
hyperkeratotic skin suggestive of
manual labor
Other Skin Manifestations
Lipodystrophy (below): reported in ~ 20% of
JDM patients . Can be generalized, partial,
or localized; characterized by a progressive,
slow, and symmetrical loss of subcutaneous
fatty tissue, which is often most noticeable
over the face and the limbs.
Calcinosis (above): seen in 12-43% of JDM patients,
this tends to be a sign of chronic disease and rarely
presents at diagnosis. These are calcium salt
deposits from muscle inflammation that deposit in
subcutaneous tissues, often over pressure-bearing
surfaces. These can be superficial and can open to
the environment, expressing calcium material, and
can become superinfected. These can self-resolve,
lessen in size, or remain unchanged. Trauma can be
associated with formation. If they occur over joints
they can cause joint contractures.
Muscle Weakness
• Probably affects all muscle groups, but proximal
> distal
• Most obvious in limb-girdle, neck flexors, and
trunk muscles
• May be tender, edematous, indurated
• Respiratory weakness
• In one report, ~ ¼ patients had involvement of
pharyngeal, hypopharyngeal, and palatal muscles
• Difficulty swallowing, dysphonia, nasal speech,
regurgitation of liquids through nose
• Aspiration risk
• May have Gowers’ or Trendelenberg’s sign
Gowers’ Sign
Trendelenberg’s Sign
How is it diagnosed?
1.
2.
Symmetrical weakness of the proximal musculature
Characteristic cutaneous changes consisting of heliotrope
discoloration of the eyelids, which may be accompanied by periorbital
edema and erythematous papules over the extensor surfaces of joints,
including the dorsal aspects of the metacarpophalangeal and proximal
interphalangeal joints, elbows, knees, or ankles (i.e. Gottron papules)
3. Elevation of the serum level of one or more of the following skeletal
muscle enzymes: CK, AST, LDH, Aldolase
4. EMG demonstration of the characteristics of myopathy and
denervation
5. Muscle biopsy documenting histological evidence of necrosis
*** MRI of thigh muscles is preferred modality to establish presence of
myositis in many centers (symmetrical muscle edema on fat-suppressed T2weighted or STIR sequences), but is not specific for myositis as edema
associated with other myopathies can appear similar on MRI.
Definite JDM: rash + 3 other criteria
Probable JDM: rash + 2 other criteria
Revisiting the Criteria for JDM
• Although criteria used for JDM, sensitivity and
specificity not validated in children (estimated
45-90% & 90%)
• For JDM diagnosis, require rash and 2 of 4
other criteria for diagnosis
• Most institutions don’t do EMG or biopsy if
diagnosis is clear.
• MRI often being used in difficult cases, less
painful and invasive than EMG or biopsy
Typical Laboratory Findings:
• Elevated muscle enzymes: Creatinine Kinase, Aldolase, LDH, AST,
ALT
• Elevated inflammatory markers: ESR, CRP
• May have lymphopenia, but leukopenia and anemia are
uncommon at onset of disease
• Positive ANA in ~ 70-80% of patients
• Other autoantibodies commonly tested that might be positive in
JDM patients:
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Anti-Jo1 – 2-5%
Anti-Ro (SSA) – 2-8%
Anti-La (SSB) – 1%
Anti-U1RNP – 5-6%
So what happens to these kids?
• Prior to steroids: 1/3 self-resolved, 1/3 would resolve but develop
significant morbidity, 1/3 would die
• Morbidity and mortality rates have improved with the use of
steroids and DMARDs
• Mortality < 3%, 28-41% with functional disability, 37-41% with
monocyclical course
• Some patients do continue to have persistent chronic skin changes
Treatment:
• First line:
• Prednisone/Methylprednisone
• Methotrexate
• Additional treatment options:
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IVIG
Cyclosporine
Tacrolimus
Mycophenolate Mofetil
Azathioprine
Cyclophosphamide
• Adjunctive therapies:
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Physical therapy
Hydroxycholorquine
Sun protection
Calcium/Vitamin D
Board Review Question
A 7 year old girl has a 2 month history of generalized
weakness and a rash. Findings on exam include a
violaceous discoloration of the malar regions,
erythematous papules over the interphalangeal joints,
and nailfold telangiectasias. Proximal muscle strength
is 3/5.
Of the following, the MOST appropriate intial step in
evaluating this patient’s symptoms is to obtain a(n):
a. antinuclear antibody titer
b. creatine kinase concentration
c. electromyogram
d. magnetic resonance image of muscle
e. muscle biopsy