Specimen case presentation:

Learn about dermatomyositis:

Dermatomyositis belongs to a group of muscle disease called myopathies characterized by inflammation and muscle weakness. The idiopathic inflammatory myopathy is a systemic disorder affecting muscles and skin mostly, but joints, esophagus, lungs and rarely heart may also be involved. While the exact etiology is not known, infectious, genetic, immunologic, environmental and drug-induced aspects are all contributory factors. Possible triggers may be:

• Viruses, toxoplasma and borrelia species;
• Genetic components like specific HLA types;
• Polymorphisms of TNF (-308A specifically is linked to photosensitivity);
• Immunologic abnormalities;
• Abnormal T cell activity;
• Antinuclear antibodies;
• Statins;
• Penicillamine;
• Interferon;
• Anti-TNF drugs;
• Cyclophosphamide;
• Quinidine.

The cardinal symptom of the disease is a skin rash, with 40% of the patients presenting with skin disease as the sole complaint. This rash could be preceded, followed or accompanied with a muscle weakness. Other symptoms include:

• Patchy rashes with purple or red discolorations on eyelids, knuckles, elbow, knees and toes;
• Red rashes on face , neck, shoulders, upper chest, back and other regions along with swelling;
• Proximal muscle weakness (initially in climbing stairs, rising from sitting position);
• Muscle tenderness;
• Weight loss;
• Arthralgia;
• Arthritis;
• Dyspnea;
• Arrhythmia;
• Dysphagia;
• Dysphonia;
• Malignancy (in people >60);
• GI ulcers and infections in children;
• Tiptoe gait (children);
• Joint contractures;
• Subcutaneous calcifications (frequency higher in juvenile dermatomyositis).

Clinical signs like Heliotrope rash (symmetrical distribution of an erythematous rash, rare in other diseases) and Gottron papules (flat topped papules on bony prominences) are pathognomonic of the disease. Other signs include:

• Malar erythema;
• Periungual and cuticular changes;
• Poikiloderma;
• Dilated capillary loops at the base of finger nails.

Investigations carried out to confirm the diagnosis are blood tests assessing muscle enzymes, autoantibodies and imaging tests including:

• MRI;
• Chest X-ray;
• Ultrasonography;
• EMG;
• CT;
• Muscle and skin biopsy.

While there is no cure for the condition, symptomatic management involves medication, physiotherapy, surgery and treatment of systemic manifestations and complications. This makes use of:

• Administering steroids;
• immunosuppressive agents to reduce inflammation;
• Avoiding sun exposure;
• Topical steroids;
• Immunomodulatory medications;
• Methotrexate;
• Physical therapy prevents atrophy.

Surgical intervention is sometimes used for the removal of calcinosis which children are more prone to develop, which may cause nerve pain and recurrent infections.

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