Polymyositis (PM) & Dmratomyositis (DrM) Flashcards
What is Polymyositis (PM) & Dermatomyositis (DrM)
- Idiopathic disorder of connective tissues (tendon, ligaments, muscle covering)
- Inflammatory muscle disease with progressive symmetric proximal muscle weakness
PM=muscle
DrM=skin
What are some histological features that can differentiate polymyositis and dermatomyositis?
PM
1. Inflammatory infiltrate WITHIN fascicle and endomysial areas
2. Scattered or isolated necrotic fibers
DrM
1. Perivascular infiltrate AROUND fascicle
2. Muscle micro vasculature often involved
What areas are most commonly affected with PM and DrM?
- Proximal limbs, neck, and pharynx
- May affect heart, lungs, and GI systems
What is the presentation of PM and DrM?
- Progressive symmetrical proximal muscle weakness
- Usually painless
- Dysphagia
- Skin rash
- Poly arthralgias
- Muscle atrophy
What labs will aid in the diagnosis of PM and DrM?
- Creatine kinase
- Increased ESR
- +muscle bx (BC the disease is breaking down muscles)
- +Anti-Jo 1Ab
*associated with DrM, “mechanic hands” - +Anti-SRP Ab
*Seen with PM
*associated with more muscle weakness/atrophy and cardiac manifestations - +Anti-Mi-2Ab
*specific for DrM
What type of muscle biopsy’s are used for PM and DrM
PM
*endomysial involvement
DrM
*Perifascicular/Perivascular involvement
What is the first line treatment for DrM and PM?
- High-dose corticosteroids
What are the pathognomonic features of DrM?
- Heliotrope rash
*blue-ish purplish upper eyelid discoloration - Gottron’s papules
*raised scaly eruptions on the knuckles - Photosensitive poikiloderma (raised, small bumps)
*shawl or V pattern - Mechanic hands
*thickened and will appear dirty
What will be increased in DrM?
- Muscle enzymes
*aldolase
*creatine kinase - Increase ESR
- Increased incidence of malignancy
What is the difference between PMR, PM, and DrM?
With PMR there should not be weakness
