### Date : 2024-06-16 15:43 ### Topic : Dermatomyositis #medicine #rheumatology ---- ### Dermatomyositis Overview **Dermatomyositis** is an inflammatory disease characterized by muscle weakness and a distinctive skin rash. It affects both children and adults and can be associated with other autoimmune diseases or malignancies.  <Photo from: https://healthcare.utah.edu/dermatology/services/autoimmune-skin-diseases/dermatomyositis> ### Pathophysiology Dermatomyositis involves immune-mediated muscle inflammation and damage. The exact cause is unknown, but it is believed to involve a combination of genetic predisposition and environmental triggers, such as infections or certain medications. The immune system mistakenly attacks muscle and skin tissues, leading to inflammation and damage. ### Clinical Features **Muscle Symptoms:** - **Muscle Weakness:** Symmetrical, proximal muscle weakness, particularly affecting the shoulders, hips, thighs, and neck. Patients may have difficulty climbing stairs, rising from a chair, or lifting objects. - **Muscle Pain:** Myalgia or tenderness in affected muscles. **Skin Symptoms:** - **Heliotrope Rash:** A violet or dusky rash on the upper eyelids, often accompanied by swelling. - **Gottron’s Papules:** Raised, scaly bumps over the knuckles, elbows, and knees. - **Shawl Sign:** A red or purplish rash over the shoulders, upper back, and neck, resembling the shape of a shawl. - **V-sign:** A similar rash in a V-shaped pattern on the chest. - **Mechanic's Hands:** Rough, cracked skin on the sides of the fingers. **Other Symptoms:** - **Fatigue:** Generalized tiredness and malaise. - **Fever:** Low-grade fever in some cases. - **Dysphagia:** Difficulty swallowing due to involvement of esophageal muscles. - **Pulmonary and Cardiac Involvement:** Interstitial lung disease and cardiac arrhythmias can occur in severe cases. ### Diagnosis Diagnosis of dermatomyositis involves a combination of clinical evaluation, laboratory tests, imaging, and sometimes biopsy: 1. **Clinical History and Physical Examination:** - Assess for characteristic skin rashes and muscle weakness. 2. **Laboratory Tests:** - **Creatine Kinase (CK):** Elevated levels indicate muscle damage. - **Aldolase:** Another enzyme elevated in muscle damage. - **Autoantibodies:** Specific antibodies like anti-Jo-1, anti-Mi-2, and anti-MDA5 can be associated with dermatomyositis. 3. **Imaging Studies:** - **MRI:** Detects muscle inflammation and edema. - **Chest X-ray or CT:** Evaluates for interstitial lung disease. 4. **Electromyography (EMG):** - Assesses electrical activity of muscles and can detect abnormalities consistent with inflammatory myopathy. 5. **Muscle Biopsy:** - Confirms diagnosis by showing inflammation, muscle fiber degeneration, and other characteristic changes. ### Example Case Study **Patient Profile:** - **Name:** Jee Hoon Ju - **Age:** 40 - **Occupation:** Office Worker **Medical History:** - **Symptoms:** Jee Hoon Ju reports progressive muscle weakness over the past few months, particularly in his shoulders and thighs. He has difficulty climbing stairs and lifting objects. He also notices a reddish-purple rash around his eyes and on his knuckles. - **Skin Examination:** Heliotrope rash on the eyelids, Gottron’s papules on the knuckles, and a shawl sign rash on the upper back. **Laboratory Tests:** - **CK Level:** Elevated at 1500 U/L (normal range: 20-200 U/L). - **Autoantibodies:** Positive for anti-Mi-2 antibody. **Imaging:** - **MRI:** Shows muscle edema and inflammation in the thighs. **EMG:** - Abnormal electrical activity consistent with inflammatory myopathy. **Muscle Biopsy:** - Shows perivascular inflammation, muscle fiber necrosis, and perifascicular atrophy. **Diagnosis:** Based on clinical findings, elevated CK levels, positive autoantibodies, imaging, EMG, and muscle biopsy results, Jee Hoon Ju is diagnosed with dermatomyositis. ### Management 1. **Medications:** - **Corticosteroids:** First-line treatment to reduce inflammation (e.g., prednisone). - **Immunosuppressive Agents:** Methotrexate, azathioprine, or mycophenolate mofetil for patients who do not respond adequately to corticosteroids or need steroid-sparing therapy. - **Biologics:** Intravenous immunoglobulin (IVIG) or rituximab for refractory cases. 2. **Physical Therapy:** - Regular exercises to maintain muscle strength and flexibility. 3. **Skin Care:** - Sun protection to prevent rash exacerbation. - Topical corticosteroids or antimalarial drugs (e.g., hydroxychloroquine) for skin symptoms. 4. **Monitoring and Follow-Up:** - Regular follow-up visits to monitor disease progression and treatment response. - Monitoring for potential complications like interstitial lung disease and malignancies. 5. **Addressing Complications:** - Treat associated conditions such as interstitial lung disease, cardiac issues, and swallowing difficulties. ### Conclusion Dermatomyositis is a chronic inflammatory condition affecting muscles and skin. Early diagnosis and comprehensive management, including medications, physical therapy, and regular monitoring, are crucial to control symptoms, prevent complications, and improve the quality of life for patients like Jee Hoon Ju. Multidisciplinary care involving rheumatologists, dermatologists, and physical therapists is often required for optimal management.