Characteristic presentations of adult onset overlap myositis

Sharing is caring!

What are the characteristic presentations of adult onset overlap myositis?

  • • Antisynthetase antibody (ASA) syndrome
    • a. Proximal muscle weakness is typically the first manifestation. CPK usually 5 to 10 times upper limit of normal.
    • b. Mechanic’s hand is common: characterized by cracking and fissuring of the skin of the finger pads, especially the radial side of the index finger.
    • c. Some patients may have DM-like rash with heliotrope or Gottron’s papules and no mechanic’s hands.
    • d. ILD, arthritis, Raynaud’s phenomenon, and fever can also occur. Rare association with cancer in older patients. ILD can be first and most severe manifestation in some clinical subsets of ASA syndrome.
    • e. MSAs identify specific clinical subsets. Patients with both an MSA and anti-SSA/Ro (52kD) antibodies (30%) have worse disease.
    • f. Muscle pathology: defined as immune myopathy with perimysial pathology with or without perifasicular atrophy. Looks more like DM but no complement deposition. A few patients may have a biopsy that looks more like PM (endomysial inflammation) or IMNM. HLA-DRβ1∗0301 is more common in these patients.
    • g. Prognosis: 5YS 80%. Up to 33% of patients with ILD will lose lung function in spite of treatment.
  • • Myositis associated with another connective tissue disease
    • a. Most common overlap is myositis associated with systemic sclerosis. These patients frequently have MAA (anti-PM-Scl, anti-U1-ribonucleoprotein (RNP), anti-Ku, anti-U3RNP [fibrillarin]).
    • b. Other connective tissue diseases associated with myositis include mixed connective tissue disease and SLE (frequently with anti-U1-RNP) and Sjögren’s syndrome. The MAA, anti-SSA/Ro (52kD), is also frequently seen.
    • c. Some patients with a defined connective tissue disease and myositis can have MSA antibodies associated with an ASA syndrome. Suspect in connective tissue disease patients who develop myositis and/or ILD.

Sharing is caring!

You cannot copy content of this page


Sign up to receive the trending updates and tons of Health Tips

Join SeekhealthZ and never miss the latest health information

Scroll to Top