“Myositis” is an umbrella term for several conditions in which the immune system attacks muscle, and sometimes the skin, lungs, and joints. Getting the type right matters, because it changes the treatment.
Your team works out which type you have from your history and examination, your bloodwork (including CK and a myositis-antibody panel), and, where needed, nerve and muscle testing (EMG), MRI, or a muscle biopsy. The pattern of weakness, the skin findings, whether the lungs are involved, and your antibodies all help place you in the right group, which points to the right treatment.
Muscle weakness together with distinctive skin changes: a purple eyelid rash (heliotrope), raised patches over the knuckles (Gottron’s papules), and rashes across the shoulders and chest. It can involve the lungs, and it carries a higher risk of certain cancers, so screening is part of care. It usually responds to immune treatment.
Weakness of the muscles closest to the trunk, the hips, thighs, and shoulders, without the skin changes of dermatomyositis. With careful testing it is now diagnosed less often than in the past, and many cases are reclassified as necrotizing myopathy or an overlap condition. It responds to immune treatment.
Severe, sometimes rapid weakness with very high muscle-enzyme (CK) levels and muscle-fibre death seen on biopsy. It is linked to specific antibodies (anti-SRP or anti-HMGCR), and the HMGCR type is sometimes triggered by statin exposure. It often needs prompt, combined immune treatment.
Usually starts after age 50 and progresses slowly. Weakness is often uneven and affects grip (finger flexors) and the front of the thigh (quadriceps), with swallowing difficulty over time. Unlike the others, IBM generally does not respond to immune-suppressing medication, so exercise, therapy, and managing swallowing and falls are the mainstay.
Defined by antisynthetase antibodies (such as anti-Jo-1). It often combines myositis, interstitial lung disease, and arthritis, along with “mechanic’s hands,” Raynaud’s, and fever. Because lung involvement can shape the outlook, it is watched closely.
Juvenile dermatomyositis affects children and teenagers, and the Centre supports the move to adult care. Myositis can also overlap with other autoimmune conditions such as lupus, scleroderma, or Sjogren’s, which shapes the treatment plan.
Myositis can reach beyond muscle. It can affect the skin, the lungs (interstitial lung disease), swallowing, and, rarely, the heart. That is why the Centre brings rheumatology, neurology, and rehabilitation together and keeps direct pathways to the lung, skin, and other services, so organ involvement is caught and managed without a fresh set of referrals and waits.
To read about the treatments used across these types, see the medication guides, including the medicines used when the lungs are involved.