EMERGENCY:Rapidly worsening weakness, difficulty swallowing, or new breathlessness in a patient with myositis (possible interstitial lung disease) —call040-46324365immediately — 24 hours, 7 days— 24/7
Inflammatory Myositis: Polymyositis, Dermatomyositis & Inclusion Body Myositis
A group of autoimmune inflammatory myopathies producing muscle weakness and raised CK — each with its own pattern, its own risks, and its own treatment. Myositis antibody panel, muscle MRI, muscle biopsy, and malignancy screening at KIMS Neuroscience, Secunderabad, Hyderabad distinguish the three and guide therapy.
G72.4 · M33.0–1 · G72.41
PM · DM · IBM
Inclusion Body Myositis
040-44885000
Inflammatory myositis is a group of autoimmune inflammatory myopathies in which the immune system attacks skeletal muscle, producing weakness and elevated creatine kinase (CK). Three subtypes are covered on this page. Polymyositis (PM) causes proximal weakness with inflammatory infiltrates on muscle biopsy and is treated with corticosteroids and immunosuppressants. Dermatomyositis (DM) adds characteristic skin involvement — the heliotrope rash around the eyes and Gottron's papules over the knuckles — and is associated with malignancy in adults, so a full cancer screen is performed at diagnosis; the anti-MDA5 antibody subtype carries a risk of rapidly progressive interstitial lung disease. Inclusion body myositis (IBM) is the most common inflammatory myopathy over the age of 50, with a distinctive pattern of finger flexor and quadriceps weakness, very slow progression, and a poor response to steroids. The myositis antibody panel, muscle MRI, and muscle biopsy differentiate the subtypes and determine treatment.
- What it is
- Autoimmune inflammation of skeletal muscle causing weakness and raised CK. Three subtypes on this page: polymyositis, dermatomyositis, and inclusion body myositis.
- Polymyositis
- Symmetric proximal weakness developing over weeks to months, with inflammatory infiltrates on biopsy. Responds to corticosteroids and immunosuppressants.
- Dermatomyositis
- Proximal weakness plus heliotrope rash and Gottron's papules. Associated with malignancy in adults — full cancer screen at diagnosis. Anti-MDA5 positive disease carries a risk of rapidly progressive interstitial lung disease.
- Inclusion body myositis
- The most common inflammatory myopathy over 50. Finger flexor and quadriceps weakness, often asymmetric, progressing over years. Poor response to steroids. Anti-cN1A antibody positive in around 30% of cases.
- Diagnosis at KIMS
- Serum CK · Myositis antibody panel · NCS/EMG · Muscle MRI to target the biopsy · Muscle biopsy · Malignancy screen for dermatomyositis · Lung assessment where ILD is suspected.
- Contact KIMS
- Outpatient: 040-44885000 · Emergency: 040-46324365 · No referral required.
| Fact | Details |
|---|---|
| Condition | Inflammatory Myositis — Polymyositis, Dermatomyositis & Inclusion Body Myositis |
| ICD-10 | G72.4 · M33.0–M33.1 · G72.41 |
| Shared features | Autoimmune muscle inflammation · Muscle weakness · Elevated CK in most |
| Polymyositis | Symmetric proximal weakness · Inflammatory infiltrates on biopsy · Corticosteroids and immunosuppressants |
| Dermatomyositis | Heliotrope rash and Gottron's papules · Malignancy association in adults · Anti-MDA5 subtype: risk of rapidly progressive ILD |
| Inclusion body myositis | Most common over 50 · Finger flexor and quadriceps weakness · Slow progression · Poor steroid response · Anti-cN1A in ~30% |
| Key investigations | Myositis antibody panel · Muscle MRI · Muscle biopsy · Cancer screen (DM) · Chest imaging and lung function where ILD is suspected |
| Detailed pages | Each subtype also has its own detailed page at KIMS — see the links below |
About This Condition
Three Conditions, One Question — Which One Is It?
The inflammatory myopathies share a common mechanism — the immune system attacking skeletal muscle — and a common presentation of weakness with raised CK. But they differ in the pattern of weakness, the associated features, the risks they carry, and, most importantly, how they respond to treatment.
Polymyositis and dermatomyositis typically cause symmetric weakness of the hips, thighs, and shoulders developing over weeks to months, and both usually respond to corticosteroids and immunosuppressants. Dermatomyositis adds skin signs and, in adults, an association with cancer that makes a structured malignancy screen essential at diagnosis. The anti-MDA5 antibody subtype needs particular vigilance because of its risk of rapidly progressive interstitial lung disease.
Inclusion body myositis is different. It is the most common inflammatory myopathy in people over 50, it selectively weakens the finger flexors and quadriceps — often asymmetrically — and it progresses slowly over years. It does not respond meaningfully to steroids, so identifying it avoids years of ineffective and harmful treatment.
Each of the three conditions has its own detailed page at KIMS Neuroscience. This page brings them together so that patients and families can see how they relate and why the subtype matters.
Book a Consultation
Speak directly with our neuromuscular team — CK and myositis antibody panel, NCS/EMG, muscle MRI, muscle biopsy with neuropathological review, malignancy screening, lung assessment, and subtype-specific immunotherapy. No referral required. Monday to Saturday.
040-44885000Emergency line: 040-46324365The Three Subtypes
Polymyositis (PM)
Symmetric proximal muscle weakness — difficulty climbing stairs, rising from a chair, or lifting the arms — developing over weeks to months, with elevated CK and inflammatory infiltrates on biopsy. Treated with corticosteroids and immunosuppressants.
Dermatomyositis (DM)
The features of PM plus characteristic skin involvement: the heliotrope rash (violaceous discolouration of the upper eyelids, named after the heliotrope flower) and Gottron's papules over the knuckles. In darker skin tones the rash can be subtle.
Dermatomyositis and cancer
In adults, dermatomyositis is associated with an underlying malignancy. A full cancer screen is performed at diagnosis at KIMS and repeated during follow-up, with particular attention to the cancers common in the Indian population.
Anti-MDA5 dermatomyositis
A subtype that may have little muscle weakness but carries a risk of rapidly progressive interstitial lung disease. New breathlessness or cough in a patient with this antibody is an emergency.
Inclusion body myositis (IBM)
The most common inflammatory myopathy over 50. Weakness of the deep finger flexors (difficulty gripping) and quadriceps (knee buckling, falls), often asymmetric, with swallowing difficulty in many patients. Very slow progression over years.
Why IBM is different
IBM combines inflammation with a degenerative process in the muscle fibres, and it responds poorly to corticosteroids. Many patients arrive having received steroids for years under a different label — correct diagnosis stops that harm.
Diagnosis at KIMS
Diagnosis at KIMS
Clinical pattern and serum CK
The distribution of weakness (symmetric proximal versus finger flexor and quadriceps), the time course, and any skin, lung, or swallowing involvement, together with serum CK. Vitamin D and thyroid function are checked, as deficiency and thyroid disease can mimic myopathy.
Myositis antibody panel
Antibodies such as anti-Jo-1, anti-Mi-2, anti-MDA5, anti-TIF1-γ, and anti-cN1A help classify the subtype, predict complications such as interstitial lung disease, and indicate cancer risk.
NCS/EMG and muscle MRI
EMG confirms a myopathic pattern and excludes nerve disease. Muscle MRI shows the distribution of inflammation and identifies the best site for biopsy.
Muscle biopsy
Histology distinguishes the subtypes — including the perifascicular atrophy of dermatomyositis and the combined inflammatory and degenerative features of IBM. Performed at KIMS under local anaesthesia with neuropathological expertise.
Cancer and lung assessment
A full malignancy screen for adults with dermatomyositis, and chest imaging with lung function testing wherever interstitial lung disease is suspected.
Treatment
Treatment by Subtype
Corticosteroids and Immunosuppression
High-dose corticosteroids are the first-line treatment for polymyositis and dermatomyositis, with a gradual taper guided by strength and CK.
Azathioprine or methotrexate are added as steroid-sparing agents; mycophenolate is preferred when interstitial lung disease is present. IVIG is used for refractory disease.
Skin, Lung, and Cancer Care
Skin disease is managed alongside the muscle disease, with photoprotection and targeted therapy.
Anti-MDA5 disease with lung involvement needs early, intensive combination immunotherapy, and any cancer found at screening is treated in coordination with oncology.
Inclusion Body Myositis — Supportive Care
There is no proven drug treatment for IBM, and corticosteroids are not used. Patients arriving on steroids from a previous diagnosis are tapered off in a structured way.
Management focuses on physiotherapy, falls prevention, knee-bracing where helpful, and swallowing assessment and support.
Rehabilitation and Monitoring
Supervised exercise and physiotherapy maintain strength and function once inflammation is controlled.
Regular review of strength, CK, swallowing, and — where relevant — lung function and cancer surveillance.
Related Conditions
Each inflammatory myopathy also has its own detailed page at KIMS Neuroscience:
FAQs
Frequently Asked Questions
Weakness climbing the stairs. A rash on the eyelids. A grip that keeps failing. Inflammatory myositis takes three different forms — and the right treatment depends on knowing which one it is.
At KIMS Neuroscience, Secunderabad, Hyderabad, inflammatory myositis is diagnosed with serum CK, the myositis antibody panel, NCS/EMG, muscle MRI, and muscle biopsy, with malignancy screening for dermatomyositis and lung assessment where needed — then treated by subtype: corticosteroids and immunosuppression for polymyositis and dermatomyositis, and supportive rehabilitation without steroids for inclusion body myositis. Call 040-44885000. No referral required.
International enquiries: info@kimsneurosciences.com