Dermatomyositis and polymyositis By: Brittni McClellan

Classifications Dermatomyositis Polymyositis Perimysial Inflammation and Atrophy Endomysial Inflammation and Atrophy CD4 Lymphocytes CD8 Lymphocytes perimysium is closer to the skin and therefore has cutaneous manifestations – “dermato” endomysium is farther from the skin and therefore has no cutaneous manifestations

Polymyositis/dermatomyositis - description Inflammatory Myopathy (Myositis) Symmetric proximal muscle weakness and rash Number of Conditions in which muscle becomes damaged by non-suppurative lymphocytic inflammatory process. Pathophysiology: Autoimmune Genetics: HLA-DQ0301 Etiology: Unknown

Polymyositis/dermatomyositis - description Pathophysiology: Focal Infiltration of T-Cells Dermatomyositis: Perimysial Polymyositis: Endomysial Small number of macrophages Muscle fiber degeneration and atrophy

Polymyositis/dermatomyositis – H&P Patient History: Diagnosis: Rash + 3 Additional Criteria Fever Progressive, Symmetric Weakness of Proximal Muscles Dermatitis: Anorexia/Weight Loss Heliotrope Rash over Eyelids Fatigue Gottron Papules over Extensor Surfaces of Joints Dysphonia Elevated Muscle Enzymes Weakness EMG: Myopathy and Denervation Difficulty Rising from Floor Biopsy: Inflammatory Myositis Difficulty Climbing Stairs Difficulty Swallowing/Regurgitation through Nose Physical Exam: Rash (Dermatomyositis) Above Symptoms Nailfold Telangiectasia Straight Leg Raise <20s

Polymyositis/dermatomyositis - Diagnosis Imaging: MRI: Inflamed Muscles – Signal Enhancement Used to direct biopsy Video Swallow Study Identify Palatal or Proximal Esophageal Weakness Pulmonary Function Tests Evaluates Pulmonary Musculature and Interstitial Lung Disease Diagnosis: Autoantibodies: Normal Rheumatoid Factor Normal Complement Normal dsDNA ANA: 10-50% PM-1: 60% of Adults, Rare in Children Jo-1: Associated with Interstitial Lung Disease Enzymes: Elevated in 95% of Cases Creatinine Kinase Aspartate Aminotransferase (AST) Aldolase Lactate Dehydrogenase (LDH)

Polymyositis/dermatomyositis – treatment Medication +/- Radiotherapy Prednisone 2 mg/kg/d for 1 month Taper over months to years IV Gamma Globulin (Rash) Plaquinel (Rash) Methotrexate Cyclosporine Mycophenolate Mofetil Reticulocyte count increases in 3-4 days

Polymyositis/dermatomyositis – treatment Associated Conditions Interstitial lung disease Malignancy: Strong Association with Dermatomyositis, Less with Polymyositis Breast or Ovarian Cancer Prostate Cancer Lung Cancer Other Connective Tissue Diseases