What are the most important skin signs in dermatomyositis?

Heliotrope discolouration (violaceous periorbital oedema), Gottron's papules (erythematous papules over the knuckles and extensor surfaces), and V-sign or shawl-sign photosensitive rash over the chest and shoulders are the classic features. Mechanic's hands — hyperkeratotic fissured skin on the radial fingers — are associated with anti-synthetase antibodies including anti-Jo-1 and indicate high interstitial lung disease risk. These skin signs may precede or co-occur with muscle weakness. Any patient presenting with this combination needs urgent rheumatology referral.

How much cancer risk does dermatomyositis carry, and how is surveillance done?

Dermatomyositis carries a 25–30% cancer risk within 3–5 years of diagnosis; with anti-TIF1-γ antibody the risk reaches approximately 50%. Polymyositis has lower but measurable risk. Recommended surveillance includes CT chest/abdomen/pelvis, PET-CT where available, plus age and sex-appropriate screening (mammogram, pap smear, PSA, colonoscopy). In Australia, referral to a rheumatologist for a surveillance plan is standard. Cancer may present before, simultaneously with, or after the myositis diagnosis.

When should a GP stop a patient's statin if myositis is suspected?

Statins should be ceased immediately if immune-mediated necrotising myopathy (IMNM) is suspected. Anti-HMGCR IMNM is a statin-triggered autoimmune condition where the statin must be permanently stopped — unlike statin myopathy, where weakness resolves on cessation. Anti-HMGCR IMNM does not resolve with statin cessation alone and requires immunosuppression. Any patient on a statin presenting with proximal muscle weakness and raised CK that does not resolve within 4–6 weeks of statin cessation warrants rheumatology referral and anti-HMGCR antibody testing.

What role does intravenous immunoglobulin play in dermatomyositis?

IVIG is established second-line therapy for dermatomyositis. The ProDERM trial (NEJM 2022) confirmed that IVIG maintenance significantly improved muscle and skin disease scores in refractory dermatomyositis. In Australia, IVIG is funded through the National Blood Authority under specific criteria for inflammatory myopathy. GPs generally do not initiate IVIG; it is prescribed and monitored in rheumatology or neurology. GPs may assist with infusion referrals once initiated and monitor for adverse effects including thrombosis and renal impairment.

What is anti-MDA5 myositis and why does it require urgent review?

Anti-MDA5 (melanoma differentiation-associated gene 5) antibody-positive dermatomyositis is associated with rapidly progressive interstitial lung disease (RP-ILD), which can be fatal within weeks of onset. Paradoxically, muscle involvement may be mild or absent (amyopathic dermatomyositis). Skin ulceration and tender palmar papules are other clues. Any patient with dermatomyositis features and new breathlessness, particularly with an anti-MDA5 positive result, needs same-day respiratory and rheumatology assessment. RP-ILD requires aggressive combined immunosuppression.

Idiopathic inflammatory myopathy (polymyositis/dermatomyositis)

Polymyositis and dermatomyositis: autoimmune muscle disease in general practice

By Dr HB Lo, FACRRM Reviewed 21 October 2026 6 min read

Dermatomyositis and polymyositis are autoimmune inflammatory myopathies presenting with proximal muscle weakness, raised muscle enzymes (CK, LDH), and in dermatomyositis, characteristic skin changes including heliotrope rash and Gottron's papules. Myositis-specific antibodies — anti-Jo-1, anti-MDA5, anti-TIF1-γ — define clinical subgroups with differing cancer risk, interstitial lung disease risk, and treatment response.

Most patients need urgent rheumatology referral. GPs play a key role in early recognition, initial investigation, cancer surveillance coordination, and long-term immunosuppressant monitoring.

Proximal muscle weakness so insidious it reads as ageing or deconditioning. A rash over the knuckles dismissed as eczema. Shortness of breath attributed to poor fitness. These are the presentations of inflammatory myopathy in general practice — and the window between first symptoms and diagnosis is often 6–12 months.

Idiopathic inflammatory myopathies (IIM) include dermatomyositis (DM), polymyositis (PM), immune-mediated necrotising myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM). The 2017 EULAR/ACR classification criteria distinguish these subtypes, each with a distinct antibody profile, organ complication pattern, and cancer risk. Getting the subtype right changes management.

A. Clinical presentation and initial GP assessment

Proximal muscle weakness is the core feature shared across most subtypes. Patients report difficulty rising from a chair, climbing stairs, lifting overhead, or combing their hair. Distal hand strength is typically preserved early — unlike motor neurone disease — but IBM is an exception. Weakness is typically symmetrical.

Associated features that raise the index of suspicion:

Heliotrope rash (violaceous periorbital discolouration and oedema)
Gottron’s papules: erythematous papules over the metacarpophalangeal and proximal interphalangeal joints
V-sign and shawl-sign: photosensitive erythema over the anterior chest and upper back/shoulders
Mechanic’s hands: hyperkeratotic fissuring of the radial digits (anti-Jo-1, antisynthetase)
Calcinosis cutis: dystrophic calcium deposits, particularly in juvenile DM
Raynaud’s phenomenon
Dysphagia: pharyngeal and oesophageal involvement in severe DM/PM
Arthralgia or non-erosive arthritis

Investigations to request before referral:

Test	What it tells you
Serum CK	Elevated in most IIM; may be normal in anti-MDA5 DM or IBM
LDH, aldolase, AST	Supportive muscle enzyme elevation
FBC, UEC, LFTs	Baseline; IIM can affect kidneys indirectly
ANA, anti-Jo-1	Screening; anti-Jo-1 is the most common myositis-specific antibody
ESR, CRP	Variable; inflammation markers often mild
TSH	Exclude hypothyroid myopathy before committing to IIM diagnosis
High-resolution CT chest	Interstitial lung disease in antisynthetase and anti-MDA5 subtypes
ECG	Cardiac involvement can occur

Full myositis-specific antibody (MSA) panel is ideally ordered by or in conjunction with rheumatology. MSA panels include anti-Jo-1, anti-MDA5, anti-TIF1-γ, anti-NXP-2, anti-Mi-2, anti-SRP, anti-HMGCR, and anti-PL-7/PL-12.

B. Differential diagnosis and antibody-guided subtyping

Conditions to exclude:

Hypothyroid myopathy (high yield — TSH is mandatory)
Statin myopathy and rhabdomyolysis
Inclusion body myositis (IBM: asymmetric, finger flexor weakness, quadriceps atrophy, older males; does not respond to immunosuppression)
Motor neurone disease (lower motor neurone or mixed; EMG essential)
Limb-girdle muscular dystrophy (genetic testing, dystrophin deficiency)
Overlap connective tissue disease (SLE, MCTD, systemic sclerosis)
Paraneoplastic myopathy (cancer-associated)

Antibody-to-phenotype mapping (clinically important):

Antibody	Association
Anti-Jo-1 (most common antisynthetase)	ILD, arthritis, mechanic’s hands, Raynaud’s — antisynthetase syndrome
Anti-MDA5	Amyopathic/hypomyopathic DM + rapidly progressive ILD; skin ulceration
Anti-TIF1-γ	Dermatomyositis + cancer association (~50% cancer risk); classic skin features
Anti-NXP-2	Juvenile DM calcinosis; adult DM cancer association
Anti-HMGCR	Statin-associated IMNM; does NOT resolve on statin cessation alone
Anti-SRP	Severe IMNM; statin-unrelated; cardiac involvement
Anti-Mi-2	Classic DM; good treatment response; lower cancer risk

C. Cancer surveillance

Dermatomyositis carries a 25–30% cancer association (standardised incidence ratio 3–7 compared to the general population), with the highest risk in the first 1–3 years. Anti-TIF1-γ positive DM approaches 50% cancer risk. Cancer types mirror the general population pattern: lung, breast, ovarian, colorectal, and haematological.

Polymyositis carries a lower but real cancer risk (SIR approximately 1.4–2). Anti-HMGCR IMNM has low cancer association. IBM is not cancer-associated.

Surveillance approach (rheumatology-guided):

CT chest/abdomen/pelvis at diagnosis and 6–12 monthly for 3–5 years
PET-CT for high-risk patients (anti-TIF1-γ, anti-NXP-2 male)
Age- and sex-appropriate screening: mammogram (MBS Item 59300), bowel cancer screening (NBCSP), cervical screening (MBS Item 73070), PSA discussion for males over 50
Tumour markers: CA-125, CA19-9, CEA where indicated by clinical context

The GP’s role is to coordinate the surveillance schedule and ensure results are acted upon alongside the rheumatologist’s review calendar.

D. Treatment overview and MBS/PBS items

Treatment is initiated and supervised by rheumatology. The GP’s role is monitoring, coordinating cancer surveillance, managing comorbidities, and recognising complications.

First-line: High-dose prednisolone (0.5–1 mg/kg/day). PBS Item 2356 (prednisone 1 mg, 5 mg, 25 mg tablets).

Steroid-sparing (second-line immunosuppressants):

Methotrexate (PBS Item 2059 — listed for inflammatory arthritis; may be used off-label for myositis or under rheumatology PBS authority)
Azathioprine
Mycophenolate mofetil (particularly for ILD in antisynthetase syndrome)
Hydroxychloroquine for skin-predominant DM (PBS Item 4721)

IVIG (ProDERM trial — Aggarwal, NEJM 2022): IVIG significantly improved Total Improvement Score (TIS) versus placebo in dermatomyositis. In Australia, funded under National Blood Authority criteria for refractory inflammatory myopathy. Initiation requires NBA authorisation; GPs may facilitate infusion referrals once authorised by rheumatology.

Rituximab (RIM trial — Oddis, Arthritis Rheum 2013): The RIM trial showed that most rituximab-treated patients with refractory DM/PM improved, though the primary endpoint was not met. Rituximab is used off-label in refractory cases. The anti-Jo-1 and anti-Mi-2 antibody-positive subgroups showed the strongest responses.

Anti-HMGCR IMNM: Statin must be permanently ceased. Immunosuppression is required regardless — anti-HMGCR IMNM will not remit on statin cessation alone. This is a critical education point for patients who expect weakness to improve after stopping the statin.

Anti-MDA5 RP-ILD: Aggressive combined immunosuppression (high-dose corticosteroids + calcineurin inhibitor + cyclophosphamide or rituximab). Outcomes are poor with delayed treatment; same-day escalation to respiratory medicine or ICU is appropriate for deteriorating respiratory function.

E. Monitoring in general practice

Once established on treatment, the GP plays an important role in shared care:

Prednisolone: blood pressure, fasting glucose/HbA1c, bone mineral density (osteoporosis prevention), eye review (cataracts, glaucoma), weight, infection risk
Methotrexate: FBC, UEC, LFTs every 3 months; folate supplementation (5 mg daily); avoid NSAIDs and alcohol
Azathioprine: FBC every 3 months; check TPMT enzyme activity before starting; LFTs
Hydroxychloroquine: baseline ophthalmology review (retinopathy screening) and every 5 years if long-term use
IVIG: monitor for thromboembolism, haemolysis, renal impairment post-infusion
Vaccination: influenza annually (MBS Item 10655); pneumococcal (MBS Item 10659); zoster (Shingrix, two-dose, recommended pre-immunosuppression if possible); COVID-19 boosters; avoid live vaccines on immunosuppressants

Muscle enzyme monitoring (CK) is useful for tracking disease activity but must be interpreted alongside clinical assessment — CK may normalise while disease remains active in treated patients.

When to escalate urgently

Send to emergency or arrange urgent same-day review if:

Acute respiratory deterioration in anti-MDA5 DM or antisynthetase syndrome (rapidly progressive ILD)
Severe dysphagia causing aspiration risk or dehydration
Cardiac involvement: arrhythmia, pericarditis, myocarditis
Rhabdomyolysis with very high CK (>10,000 U/L), renal impairment, myoglobinuria
Severe weakness preventing ambulation
Signs of sepsis in immunosuppressed patients

For new diagnoses or patients with constitutional symptoms and skin or muscle features: urgent (within 2 weeks) rheumatology referral is appropriate. Do not delay for an MSA panel result — begin the referral and order investigations concurrently.

What this article is and is not

This article is a clinical orientation for GPs who may be the first to recognise inflammatory myopathy or who are providing shared-care follow-up under rheumatology supervision.

It is not a substitute for specialist assessment, MSA interpretation, treatment initiation, or cancer surveillance planning. All patients with suspected inflammatory myopathy need rheumatology review.

Information is consistent with eTG Rheumatology (2024), EULAR/ACR 2017 classification criteria, National Blood Authority criteria for IVIG, and cited trials as at the date of publication. Clinical guidelines evolve; verify current recommendations before applying to individual patients.

Sources cited

Therapeutic Guidelines: Rheumatology — eTG (2024). Inflammatory myopathy. https://tgldcdp.tg.org.au
Lundberg IE et al. (2017). European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies. Arthritis Rheumatol. https://doi.org/10.1002/art.40230
Australian Rheumatology Association. Clinical practice guidelines for inflammatory myopathy. https://rheumatology.org.au
Aggarwal R et al. (2022). Inclusion of endurance exercise in physical therapy treatment improved outcome in patients with moderate to severe dermatomyositis (ProDERM). N Engl J Med. https://doi.org/10.1056/NEJMoa2117349
Oddis CV et al. (2013). Rituximab in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis (RIM trial). Arthritis Rheum. https://doi.org/10.1002/art.37998
Mammen AL. (2016). Statin-associated autoimmune myopathy. N Engl J Med. https://doi.org/10.1056/NEJMra1515163
Sato S et al. (2013). Distinct features of anti-MDA5 dermatomyositis from anti-Jo-1 dermatomyositis. Rheumatology. https://doi.org/10.1093/rheumatology/ket149
National Blood Authority Australia. (2024). Conditions, Criteria, Indications and Dosing for IVIG. https://www.blood.gov.au/system/files/Conditions-and-criteria.pdf
Hill CL et al. (2001). Frequency of specific cancer types in dermatomyositis and polymyositis. Lancet. https://doi.org/10.1016/S0140-6736(01)05443-8
Australian Medicines Handbook. (2024). Myositis: disease-modifying agents. https://amhonline.amh.net.au

Frequently asked questions

What are the most important skin signs in dermatomyositis?

Heliotrope discolouration (violaceous periorbital oedema), Gottron's papules (erythematous papules over the knuckles and extensor surfaces), and V-sign or shawl-sign photosensitive rash over the chest and shoulders are the classic features. Mechanic's hands — hyperkeratotic fissured skin on the radial fingers — are associated with anti-synthetase antibodies including anti-Jo-1 and indicate high interstitial lung disease risk. These skin signs may precede or co-occur with muscle weakness. Any patient presenting with this combination needs urgent rheumatology referral.
How much cancer risk does dermatomyositis carry, and how is surveillance done?

Dermatomyositis carries a 25–30% cancer risk within 3–5 years of diagnosis; with anti-TIF1-γ antibody the risk reaches approximately 50%. Polymyositis has lower but measurable risk. Recommended surveillance includes CT chest/abdomen/pelvis, PET-CT where available, plus age and sex-appropriate screening (mammogram, pap smear, PSA, colonoscopy). In Australia, referral to a rheumatologist for a surveillance plan is standard. Cancer may present before, simultaneously with, or after the myositis diagnosis.
When should a GP stop a patient's statin if myositis is suspected?

Statins should be ceased immediately if immune-mediated necrotising myopathy (IMNM) is suspected. Anti-HMGCR IMNM is a statin-triggered autoimmune condition where the statin must be permanently stopped — unlike statin myopathy, where weakness resolves on cessation. Anti-HMGCR IMNM does not resolve with statin cessation alone and requires immunosuppression. Any patient on a statin presenting with proximal muscle weakness and raised CK that does not resolve within 4–6 weeks of statin cessation warrants rheumatology referral and anti-HMGCR antibody testing.
What role does intravenous immunoglobulin play in dermatomyositis?

IVIG is established second-line therapy for dermatomyositis. The ProDERM trial (NEJM 2022) confirmed that IVIG maintenance significantly improved muscle and skin disease scores in refractory dermatomyositis. In Australia, IVIG is funded through the National Blood Authority under specific criteria for inflammatory myopathy. GPs generally do not initiate IVIG; it is prescribed and monitored in rheumatology or neurology. GPs may assist with infusion referrals once initiated and monitor for adverse effects including thrombosis and renal impairment.
What is anti-MDA5 myositis and why does it require urgent review?

Anti-MDA5 (melanoma differentiation-associated gene 5) antibody-positive dermatomyositis is associated with rapidly progressive interstitial lung disease (RP-ILD), which can be fatal within weeks of onset. Paradoxically, muscle involvement may be mild or absent (amyopathic dermatomyositis). Skin ulceration and tender palmar papules are other clues. Any patient with dermatomyositis features and new breathlessness, particularly with an anti-MDA5 positive result, needs same-day respiratory and rheumatology assessment. RP-ILD requires aggressive combined immunosuppression.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.