Connective Tissue Diseases

Question 1

Juvenile dermatomyositis (JDM)

Answer 1

• Is a systemic, autoimmune inflammatory muscle disorder and vasculopathy that affects children younger than 18 years.
• JDM primarily affects the skin and the skeletal muscles.
• Characteristic findings include Gottron papules, a heliotrope rash, calcinosis cutis, and symmetrical, proximal muscle weakness.

Question 2

Pathophysiology of JDM

Answer 2

Humoral attack against the muscle capillaries and small arterioles.

Question 3

Genetics of JDM

Answer 3

Several protective DQA1 alleles have been identified in JDM

Question 4

JDM is a polygenic disorder, and other polymorphic loci appear to be risk factors in Caucasian JDM patients…

Answer 4

… These include the tumor necrosis factor-a (TNF-a) polymorphism TNFa-308A, which is associated with increased stimulated peripheral blood mononuclear cell production of TNF-a.

Question 5

anti-p155 autoantibody associated with DQA1*0301 is ….

Answer 5

a risk factor allele

Question 6

DQA1 alleles….

Answer 6

has been found to be a severity factor,

associated with the development of calcinosis and a chronic illness course

Question 7

HLA-DRB1*0301 risk-factor allele is for …

Answer 7

Hispanic patients.

Question 8

In, the majority of children with JDM report an antecedent

Answer 8

respiratory or gastrointestinal infection within 3 months before symptom onset, further supporting environmental factors affecting disease development.

Question 9

Noninfectious exposures associated with the onset of individual cases of JDM …

Answer 9

ultraviolet light, growth hormone, drugs (D-penicillamine and carticaine), and vaccines (hepatitis B,
influenza, and MMR), but these require confirmation in case controlled studies.

Question 10

Clinical features cardiac

Answer 10

arrhythmias, pericarditis or myocarditis

Question 11

Clinical features pulmonary

Answer 11

pneumomediastinum or pneumothorax

Question 12

Gastrointestinal complications

Answer 12

hepatitis and cholestasis

Question 13

Hematologic sequelae

Answer 13

hemolytic anemia, thrombocytopenia, and myelofibrosis

Question 14

neurologic manifestations

Answer 14

central nervous

system vasculitis, peripheral neuropathy, and retinopathy

Question 15

GU manifestations

Answer 15

myoglobinuria, testicular inflammation, and ureteral necrosis of the middle segment of the renal pelvis

Question 16

Etiology of JDM

Answer 16

Coxsackie B virus
Parvovirus B19 (Herpes)
Enteroviruses
Streptococcus species
Mycoplasma

Question 17

Diagnosis of JDM (Labwork)

Answer 17

• Laboratory studies include an erythrocyte sedimentation rate (ESR); muscle enzyme levels; lupus profile (ie, antinuclear antibody [ANA], extractable nuclear antigens [ENA]);
• Myositis-specific antibody assays such as antibodies against the aminoacyl t-RNA synthetases (ie, anti-Jo-1 antibody),
• Antisignal recognition particle (anti-SRP antibody), and nuclear helicase (anti-Mi-2 antibody).

Question 18

Anti-p155 may become an important…

Answer 18

diagnostic test when clinical assays become available.

Question 19

The p155/140 kDa doublet protein, a myositis-associated autoantibody, has been identified in…

Answer 19

…29% of patients with JDM and may correlate with more extensive cutaneous involvement, including ulcerations and edema.

Question 20

Which levels of muscle enzymes will elevated early in the disease course…

Answer 20

aspartate aminotransferase,
lactate dehydrogenase,
creatine kinase,
aldolase.

Question 21

Dx of using nailfold capillaroscopy:

periungual capillary changes are present in….

Answer 21

… up to 90% of JDM patients, although the abnormalities are not specific to
JDM and may be seen in other systemic connective tissue diseases, especially scleroderma and mixed connective tissue
disease

Question 22

Are muscle biopsies used in diagnosis?

Answer 22

A muscle biopsy is not usually performed to confirm the diagnosis of JDM, as it is for adult myositis. However, it is needed in the workup of juvenile polymyositis.

Question 23

Tx of JDM

Answer 23

Patients with acute, life-threatening complications such as severe dysphagia, gastrointestinal ulceration, myocarditis
or severe, early interstitial lung disease may benefit from repeated pulses of high-dose intravenous methylprednisolone, IVIG, and/or cyclophosphamide. Patients with dysphagia often require dietary modifications, including pureed foods,
eating upright, or nasojejunal feeding

Question 24

Although similar in many respects to adult dermatomyositis with characteristic skin findings and muscle weakness, JDM is often associated …

Answer 24

…with calcinosis cutis, cutaneous ulcerations, and vasculopathy characterized by intimal proliferation of small blood vessels and infarctions.

Question 25

Diagnosis of JDM has been based on the following 5 criteria, specified by Bohan and Peter in 1975

Answer 25

``` Characteristic skin rash Proximal muscle weakness Elevated muscle enzymes Myopathic changes on electromyography Abnormal muscle biopsy findings ```

Question 26

Diagnosis of JDM has been based on the following 5 criteria, specified by Bohan and Peter in 1975

Answer 26

``` Characteristic skin rash (Heliotrope rash, Gottron papules) Proximal muscle weakness Elevated muscle enzymes Myopathic changes on electromyography Abnormal muscle biopsy findings ```