MUSCLE WEAKNESS & SKIN RASH( DERMATOMYOSITIS )Dr. Mohammad Tanvir IslamAssistant Professor , Dept of MedicineBangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
IS THIS A CASE OF MYOPATHY?? Proximal muscle weakness evident by- Difficulty in standing from sitting position, combing hair etc. Normal tendon reflexes Pain & tenderness often present
WHAT MAY BE THE CAUSE OF THIS MYOPATHY Inflammatory myopathy Drug induced Endocrine Infection Alcohol
MYOPATHY WITH SKIN RASH Dermatomyositis Steroid induced myopathy Hypothyroidism Other CTDs
DERMATOMYOSITIS Double peak of onset Average age of onset is 40 In 40% individuals the skin disease is the sole manifestation at onsetMuscle disease may occur- Concurrently, Precede the skin disease, or Follow the skin disease by weeks to years.
Heliotrope rash-violaceous colour-Periorbital edemapresentSKIN RASH IN DERMATOMYOSITIS
Gottrone’s papulesInvolves the dorsal surface of MCP and IP jointsSKIN RASH OF DERMATOMYOSITIS
Periungual telengiectasiaSKIN RASH OF DERMATOMYOSITIS
Rash in Shawl distributionSKIN RASH OF DERMATOMYOSITIS
COMPLICATIONSDermatomyositis & malignancy 6-7 fold increase risk of malignacy Usually early within 3 years of diagnosis chances decreases thereafter Highest in patients diagnosed after 45yrs of age Ovarian and gastric cancer and lymphoma are most common
CLASSIFICATION CRITERIA FOR POLYMYOSITISAND DERMATOMYOSITIS*1. Skin lesions Heliotrope: red-purple edematous erythema on the upper palpebra Gottron’s sign: red-purple keratotic, atrophic erythema or macules on the extensor surface of finger joints Erythema on the extensor surface of extremity joints, slight raised red-purple erythema over elbows or knees2. Proximal muscle weakness (upper or lower extremity and trunk)3. Elevated serum creatine kinase or aldolase level4. Muscle pain on grasping or spontaneous pain5. Myogenic changes on electromyography (short-duration, polyphasic motor unit potentials with spontaneous fibrillation potentials)6. Positive anti-Jo-1 antibody test (histidyl-tRNA synthetase)7. Nondestructive arthritis or arthralgias8. Systemic inflammatory signs (temperature: more than 37°C [98.6°F] at axilla, elevated serum C-reactive protein level or accelerated erythrocyte sedimentation rate of more than 20 mm per hour by Westergren)9. Pathologic findings compatible with inflammatory myositis (inflammatory infiltration of skeletal evidence of active regeneration may be seen)
CLINICAL CRITERIA 1975, Bohan and Pete Set of 5 criteria to aid in the diagnosis and classification of dermatomyositis and polymyositis1. progressive proximal symmetrical weakness,2. elevated levels of muscle enzymes,3. an abnormal finding on electromyography,4. an abnormal finding on muscle biopsy5. Cutaneous disease.
SUBSETS OF MYOSITISBohan and Peter suggested 5 subsets of myositis, as follows : Dermatomyositis Polymyositis Myositis with malignancy Childhood dermatomyositis/polymyositis Myositis overlapping with another collagen-vascular disorder Others- postmyopathic dermatomyositis amyopathic dermatomyositis [ADM], or dermatomyositis sine myositis
HOW WILL YOU INVESTIGATEEnzymes – CK Aldolase LDH carbonic anhydrase isoenzyme III
ANTIBODIES ANA commonly positive (60-80%) Anti –Mi-2 highly specific but sensitivity only 25% Anti-Jo-1 more in polymyositis,associated with ILD,raynauds and arthritis (positive in 20%) autoantibody against p155 highly associated with cancer
IMAGING MRI- useful in diagnosing inflammatory myopathy(even in patients without weakness), it also helps in taking muscle biopsy in choosing proper site EMG- helps to differentiate from neuropathy and choosing biopsy site. CXR Barium swallow USG CT scan
HISTOPATHOLOGICAL FINDINGS Findings on muscle biopsy can be diagnostic. Perivascular and interfascicular inflammatory infiltrates with adjoining groups of muscle fiber degeneration/regeneration This contrasts with polymyositis infiltrates, which are mainly intrafascicular (endomysial inflammation) with scattered individual muscle fiber necrosis.
Figure 2A, B: Depletion of capillariesin dermatomyositis (A) withdilatation of the lumen of theremaining capillaries,compared with a normalmuscle (B). C: Perifascularatrophy in dermatomyositis.D: Endomysial inflammationin polymyositis and inclusion-body myositis withlymphocytic cells invadinghealthy fibres. E: The MHC-I/CD8 complex in polymyositisand inclusion-body myositis. HISTOPATHOLOGICAL FINDINGS OF DERMATOMYOSITIS & POLY MYOSITIS Source: The Lancet 2003; 362:971-982 (DOI:10.1016/S0140-6736(03)14368-1) Terms and Conditions
TREATMENT Oral prednisolone is the mainstay of treatment 0.5-1.5 mg/kg starting dose.given untill CK level is normal , then tapered slowly over 12 month period Prednisolone itself worsen myopathy in some cases and steroid induced myopathy is differentiated by sparing the neck flexor strength
TREATMENT Other drugs used- methotrexate,azathiprine, cyclophosphamide, cyclosporine IV immunoglobulin for refractory cases Physiotherapy
PROGNOSIS Spontaneous remission in 20% 5% have fulminant progression and eventual death Poor prognostic factor-recalcitrant disease, delay in diagnosis, older age, malignancy, fever, asthenia-anorexia, pulmonary interstitial fibrosis, dysphagia and leukocytosis. Cause of death-Malignancy, cardiac and pulmonary dysfunction, and infection