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anti-Synthetase Antibody Syndrome


Versione in italiano

Polymyositis (PM), Dermatomyositis (DM), and anti-Synthetase Antibody Syndrome (aSS) belong to the idiopathic inflammatory myopathies (IIMs). These particular syndromes are characterized by an abnormal activation of the immune system against muscles and other organs.

Patients affected by PM, DM, and aSS are clinically heterogeneous, but they all exhibit a subacute onset of weakness in the proximal arm/leg muscles (typically symmetrical). Patients often complain of difficulties when standing up, climbing stairs, and/or lifting weights. DM patients also suffer from skin involvement before or after the onset of muscular symptoms. These skin manifestations can frequently present as:

  • Gottron’s papules (Violaceous papules and plaques over the hand, wrist and elbow)
  • Eliothropus rash (Periorbital erythema with edema, most often of the upper eyelids)
  • Calcinosis of the skin
  • Rash over sun-exposed skin
  • Telangiectasias around the nails

Patients with PM/DM may also suffer from lung involvement (either infective pneumonitis linked with difficult deglutition or interstitial inflammation), cardiac involvement, dysphagia (consequence of altered esophageal motility) and arthritis.
aSS is a recently defined disease characterized by the presence an anti-synthetase antibody, myopathy, non-destructive arthritis, Mechanic's hands (hyperkeratotic, scaling, and fissuring of fingers and/or palms), Raynaud’s phenomenon (Episodic vasospasm of fingers and toes in response to cold, with typical color changes) and Interstitial Lung Disease.
Diagnosis is based upon physical examination, laboratory findings (elevation of muscular enzymes like creatin phosphor kinase (CPK) and aldolase, and characteristic autoantibodies), electromyography, and muscular biopsy. In these pathologies it is also common to find mononuclear infiltration and necrosis/renewal of muscular fibers. In DM, B lymphocytes are usually found around blood vessels in the muscles. In PM, T lymphocytes and macrophages are found around muscle sheaths.
DM can be associated with other autoimmune disease and cancer (especially breast/uterus/ovarian cancer in women, lung/prostatic/gastrointestinal cancer in men) so cancer must be ruled out during diagnostic workup.

IIMs are rare connective tissue diseases. PM/DM usually affect people under 60 years old and women are affected 2-3 times more than men. There are 5 to 10 new cases per million people of DM every year with a prevalence of 6 to 7 cases per 100,000 people.
DM is usually diagnosed either in children between 4-14 years old or in adults between the ages of 40-60 years old.
The annual incidence of PM has been reported to be 4 to 7 per million people.

The hallmark of myositis treatment is corticosteroid therapy and is effective in 70% of patients. For treatment of corticosteroid-resistant patients and to avoid excess use of steroids, other immunosuppressive drugs are commonly used, like tacrolimus, methotrexate, micofenolate mofetil and intravenous immunoglobulins. In recent years several new drugs have been devised and are currently used like monoclonal agents e.g. rituximab, and anti B cell drugs.

REFERRING DOCTORS for this desease

at Ospedale San Raffaele

Ospedale San Raffaele - Milano, via Olgettina 60, 20132 Milano, Italia - Tel. 02 26 431
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