The diagnosis is based on

• Medical history of symptoms or proven pathology
  • Lungs
  • Muscles
  • Arthritis (Arthritis)
  • Skin
  • Antibodies
• Pulmonary abnormalities
• Myositis
• Antibodies
• Exclude another reason (Differential diagnosis)

Disease history

• Debut (time) for onset of symptoms: dry cough, dyspnea at physical stress

• Lungs

  • Dry cough
  • Dyspnea at physical stress
  • Quickly progressive symptoms from lungs (increase from week to week)?

• Muscles (Myositis)

  • Pain
  • Weakness
  • Dysphagia (esophagus affection)
  • Proximal (classical) and / or distal affection

Immunomodulatory treatment to date

• Methyl prednisolone (SoluMedrol)
• Prednisone (Maximum and actual dose)
• Cyclophosphamide (Sendoxan; treatment duration and dose), Rituximab (Rixathon, MabThera), Mycophenolate (CellCept), Azathioprine (Azathioprine), methotrexate, others)

Clinical examination

• Lungs

  • Crepitations over lungs by auscultation?

• Skin

  • Mechanic's Hands (Cracked dry skin on hands)
  • Gottron's sign or papules (red-violet color over MCP joints)
  • V-shaped sign (chest and throat) (Red-blue color)
  • Shawl-shaped characters (neck and back) (Red-blue color)
  • Heliotropic rash (eyelid)
  • Raynaud's phenomena (Three-phasic)

• Joint

  • 90-90 deformity in thumb
  • Rheumatoid arthritis like courses occur

• Muscles

  • Muscular atrophy and reduced force (rising from chair / squat without support?)
  • Weaker muscle strength (proximal) in the thighs, arms or neck?
  • Reduced walking function?

Laboratory tests

• Creatine kinase (CK) is usually moderately elevated
• AST and LD (usually elevated)
• Antibodies ( "Myositis-specific)
  • Jo-1, P1-7 or P1-12 (+ some very rare) are usually present
  • ANA (antinuclear antibody) of 50%
  • SSA (Ro 52) is often positive in low titer without at the same time Sjögren's syndrome or SLE may be present

Supplementary Medical Examination

• Lung function tests (including DLCO)

• Radiological

  • HRCT examinations of lungs
  • X-ray examination may be normal even in case of major lung changes
  • MRI examination (with contrast) of proximal muscles, most of both thighs
    • MRI locates muscle groups with the most manifestations. Localization for biopsy (see below)
  • X-ray or manometry of esophagus (swallowing)

• Laboratory

  • Rutine (Hb, Erythrocyte Sedimentation Rate (ESR), CRP, leukocytes, platelets, liver enzymes, K, Na, Cl, Ca, Creatinine, TSH, T4, creatine kinaseCK)
  • Myositite specific autoantibodies (a-Jo-1 in 80-90%, Pl-7 and Pl-12 and others are less frequent)
  • Anti-SSA (Ro) antibody (as by Sjögren's syndrome og SLE) is not uncommon

• Capillaroscopy 

  • Pathological findings are somewhat less frequent than at Systemic sclerosis

• Muscle Biopsy

  • Will be performed if increased CK, edema on MRI, or positive EMG (electromyography).

Malignancy

• Malignancy investigations should be considered (especially in adult dermatomyositis)
  • Gynecological examination, CT abdominal examination, electrophoresis urine / serum, stool of blood test, colonoscopy, other investigations if clinical suspicion
  • Alternatively: PET / CT

Differential diagnosis

• Differential diagnoses of the antisynthetase syndrome are described here

Referral to specialist

Patients resident in Oslo and the Health Region South-East will be given priority Rheumatology Department, Rikshospitalet: Mailbox 4950 Nydalen, 0424 OSLO. The department also receives patients from the country otherwise as far as capacity is concerned. If urgent, doctors can confer with the guard doctor (via switchboard on phone 02770)

Myositis (BINDEVEVSSYKDOMMER.no)

Antisynthetase syndrome, BINDEVEVSSYKDOMMER.no

• Bindevevssykdommer.no
• Vaskulitt.no