Myositis

Myositis is inflammation of muscle. The commonest autoimmune forms — polymyositis, dermatomyositis, inclusion body myositis, immune-mediated necrotising myopathy — cause weakness (mostly of shoulders and hips), sometimes with a rash, swallowing trouble, or breathing symptoms. Early diagnosis and treatment preserve function.

Features

• Symmetrical weakness — difficulty climbing stairs, getting out of a car/floor, raising arms to wash hair.
• Rising and stable (polymyositis) or fluctuating (dermatomyositis) pattern.
• Muscle tenderness — sometimes; often minimal.
• Skin rash in dermatomyositis — heliotrope (purplish) rash around eyes; Gottron papules on knuckles; "shawl sign" on upper back.
• Swallowing difficulty, hoarseness — pharyngeal muscle involvement.
• Breathlessness — diaphragm weakness or associated interstitial lung disease.
• Joint pain, Raynaud's phenomenon.

Evaluation

• CPK very elevated (often).
• Autoantibodies — myositis-specific and myositis-associated antibodies guide subtype.
• EMG shows characteristic pattern.
• Muscle MRI.
• Muscle biopsy — gold standard.
• Screen for associated cancer in dermatomyositis (particularly over 50) — CT chest/abdomen, PAP, mammogram, PSA; evaluation depends on age/sex.
• Screen for lung disease (HRCT + pulmonary function).
• Evaluate swallowing, heart.

Treatment

• High-dose steroids initially; taper.
• Steroid-sparing immunosuppressants — several oral options under rheumatology supervision.
• IVIG or biologics for severe or refractory disease.
• Physiotherapy throughout — maintain strength and range.
• Swallowing therapy when needed.
• Screen and treat associated conditions — cancer, ILD, cardiac.
• Vaccines, bone health, fall prevention — steroids add risks.
• Care at a rheumatology / neuromuscular centre preferred.

Myositis is often misdiagnosed initially as "weakness from age/fatigue." New proximal weakness, rising CPK, or the characteristic dermatomyositis rash deserves prompt rheumatology review — early treatment preserves substantial function.