Dermatomyositis

History Taking

Chief Complaint

• Persistent rash on hands and face

• Progressive muscle weakness

History of Presenting Complaint

• Describes a heliotrope rash (purplish color) on the upper eyelids

• Gottron's sign - rash over the knuckles, elbows and knees

• Complaints of muscle weakness, especially in proximal muscles like the hips and shoulders

• Dysphagia or difficulty swallowing

• Possible fatigue, fever, and unintended weight loss

System Review

• Musculoskeletal: Symmetrical proximal muscle weakness, difficulty getting up from a sitting position or climbing stairs

• Dermatological: Rash on sun-exposed areas, photosensitivity, dry and itchy skin, mechanic's hands (cracked and rough skin on the hands)

• Respiratory: Shortness of breath, possible interstitial lung disease

• Gastrointestinal: Dysphagia, possible risk of aspiration due to muscle weakness

• Cardiac: Irregular heart rhythms or congestive heart failure in severe cases

Past Medical History

• Could have a history of other autoimmune diseases (SLE, Rheumatoid Arthritis, etc.)

• History of Raynaud’s phenomenon

Drug History

• No significant findings unless the condition is drug-induced (rare), in which case there might be a history of use of certain drugs like statins, hydroxyurea, penicillamine, etc.

Family History

• Family history of autoimmune diseases could be a potential indicator

Personal History

• Lifestyle factors, such as sunlight exposure, could be relevant if patient mentions a relationship between sun exposure and skin symptoms

OBG History

• If female and of childbearing age, query about changes in menstrual cycle as autoimmune diseases can sometimes cause irregular cycles

• Dermatomyositis may flare during pregnancy or postpartum

Physical Examination

General Examination

• Heliotrope rash (purplish discoloration) on upper eyelids

• Erythematous rash on face, chest, and back (in a "shawl-like" distribution)

• Gottron's papules or sign - raised, red patches over the knuckles, elbows, and knees

• "Mechanic's hands" - cracked and rough skin on the sides of the fingers

Hands and Arms

• Gottron's papules over the knuckles

• Possible muscle atrophy in severe, chronic cases

Mouth

• Erythema or ulceration in the hard palate (rare)

Neck

• Muscle weakness could make the neck flexors weak, leading to difficulty in lifting the head off the pillow

Cardiac Examination

• Signs of heart failure such as elevated jugular venous pressure, peripheral edema might be present in case of cardiac involvement

• May have arrhythmias or other cardiac manifestations in severe cases

Respiratory Examination

• May show signs of interstitial lung disease (ILD) like bibasal fine crackles, if ILD is present

• Decreased chest expansion could be a sign of myositis involving the respiratory muscles

Abdominal Examination

• Typically not relevant in a case of dermatomyositis unless there are gastrointestinal symptoms

Neurological Examination

• Decreased muscle power, especially in proximal muscles

• Normal sensory examination, as sensory nerves are typically not involved

• Normal deep tendon reflexes, unless there is severe muscle wasting

Additional Examination

• Skin examination might reveal calcinosis (hard, calcium deposits under the skin)

• Examine the skin in sun-exposed areas and covered areas to compare the rash

• Muscle strength testing to determine the severity and extent of muscle weakness

• Joint examination for arthritis

Investigations

Laboratory Investigations

• Complete Blood Count: May show elevated white blood cells in cases of inflammation or infection

• Creatine Kinase (CK): Increased in muscle inflammation

• Aldolase: Increased in muscle inflammation

• Liver function tests: Aspartate transaminase (AST) and alanine transaminase (ALT) may be elevated due to muscle damage

• Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP): May be elevated indicating systemic inflammation

• Autoantibodies: Antinuclear antibody (ANA), anti-Jo-1, anti-Mi-2, anti-SRP, anti-PL-7, and anti-PL-12 can be positive in dermatomyositis

• Electromyography (EMG): Can show myopathic changes (short duration, low amplitude motor unit potentials)

Imaging

• MRI of muscles: Can show muscle inflammation

• Chest X-ray or High-resolution CT chest: To assess for associated interstitial lung disease or malignancy

Invasive Tests

• Muscle Biopsy: Can confirm diagnosis by showing inflammatory cell infiltrates and muscle fiber necrosis

• Pulmonary Function Tests: If there are respiratory symptoms or signs, to assess for restrictive lung disease secondary to ILD or muscle weakness

Other Tests

• Cancer screening tests: Because of the association of dermatomyositis with malignancy, appropriate screening tests like mammography, colonoscopy, pelvic ultrasound, or CT scans may be needed depending on the patient's age and risk factors

• Skin biopsy: May show interface dermatitis, a finding consistent with dermatomyositis

Management

General Management

• Patient education: Explaining the nature of the disease and the importance of adherence to medication

• Sun protection: Because of the photosensitive nature of the rash, patients should be advised to avoid direct sun exposure and use sunscreens

Medical Management

• Corticosteroids: First-line therapy for initial treatment and for flares

• Immunosuppressants: Used in conjunction with steroids or as steroid-sparing agents. Options include methotrexate, azathioprine, mycophenolate mofetil, and cyclosporine

• Intravenous immunoglobulin (IVIG): For patients who are refractory to first-line treatments or with severe disease

• Rituximab: For patients with refractory disease or intolerant to other therapies

• Topical therapies: Topical corticosteroids and calcineurin inhibitors may be helpful for skin manifestations

Surgical Management

• There are generally no specific surgical interventions for dermatomyositis unless for management of complications or associated conditions like malignancy

Other

• Physiotherapy: To maintain muscle strength and flexibility and to prevent contractures

• Speech and swallowing therapy: For those with involvement of the throat muscles leading to dysphagia

• Regular screening: For associated malignancies

• Regular follow-ups: To monitor disease progression and response to therapy