This document provides an overview of polymyositis and dermatomyositis. Polymyositis is an idiopathic inflammatory myopathy that causes symmetrical proximal muscle weakness. It is caused by defective cellular immunity and can be associated with viral infections, malignancies or drugs. Symptoms include proximal muscle weakness in the upper and lower limbs and may include extra skeletal symptoms. Investigations include blood tests, EMG and muscle biopsy. Treatment involves corticosteroids and immunosuppressive agents. Dermatomyositis is a similar condition with additional characteristic skin manifestations. Both conditions are treated with corticosteroids, immunosuppressants and addressing any skin symptoms.

2. POLYMYOSITIS
Dr.QURA_TUL_AIN

3. CONTENTS
DEFINITION
ETIOLOGY
PATHOGENISIS
SYMPTOMS AND SIGNS
INVESTIGATIONS
MANAGEMENT
PROGNOSIS

4. DEFINITION
Polymyositis is an idiopathic inflamatory myopathy
that causes symmetrical proximal muscle weakness,
elevated skeletal muscle enzyme levels,characteristic
electromyograhic pattern and muscle biopsy findings.

5. ETIOLOGY
Polymyositis is an immune-mediated syndrome secondary
to defective cellular immunity that is most commonly
associated with other systemic autoimmune diseases. It
may be due to diverse causes that occur alone or in
association with
 Viral infections
 Malignancies
 Drugs

6. CLASSIFICATION

7. PATHOGENSIS

8. SYMPTOMS
Proximal muscle weakness of both upper
and lower limbs causes
Difficulty in raising arms,lifting objects
and combing hairs
Difficulty in climbing and descending
stairs,sitting on curb and raising from
sitting posture

9. EXTRA SKELETAL SYMPTOMS
 GIT
Dysphagia(30%)
Bloating
Concipation
 Cardiac
Arrythmias
Conduction defects
 Pulmonary
Aspiration pneumonia
Interstitial lung disease(Anti jo-1)
Bronchiolitis obliterans

10.  Renal
 Acute tubular necrosis
 Joint involvement
 Arthralgia(5-25%)

11. INVESTIGATIONS
1. CBC
• Leukocytosis(50%)
1. ESR
2. Elevated muscle enzyme
level(CK,LDH,AST,ALT,ALDOLASE)
3. Antibody Findings(ANA,Myositis Specific Antibodies)
4. Electromyography(EMG)
5. Muscle Biopsy

12. DIFFERENTIAL DIAGNOSIS
 Cushing Syndrome
 Fibromyalgia
 Hyperthyroidism
 Hypothyroidism
 Polymyalgia Rheumatic
 Rheumatoid Arthritis
 Sarcoidosis
 SLE

13. TREATMENT
1. Corticosteroids
• Prednisolone(1mg/kg/day for 4to8 weeks)
• Monitor the response by
• Muscle Strength
• CK Levels
• Immunosuppressive Agents
• Indications
• No response with steroids upto 4 weeeks
• Extra Skeleton Manifestations
• Azathioprine, cyclophosphamide, chlorambucil, and
cyclosporine

14. 3. Other Agents
Intravenous immunoglobulin (IVIG)
TNF inhibitors(infliximab)
anti-CD20 monoclonal antibody(rituximab)
4. Diet
5. Activity
6. Consultations
Cardiologist
Radiologist

15. DERMATOSITIS
DEFINITION:-
Dermatomyositis is an idiopathic inflammatory myopathy
with characteristic cutaneous findings.
ETIOLOGY:-
 Genetic
 Immunologic
 Infectious
 Environmental

16. PATHOGENSIS
Dermatomyositis is considered to be the result of a humoral attack
against the muscle capillaries and small arterioles (endothelium of
the endomysial blood vessels).

17. SYMPTOMS
 Proximal Muscle Weakness
 Skin Manifestations
 Systemic Systems
SIGNS
 Heliotrope Rash
 Gottron Papules
 Dilated capillary loops at base of finger nails

19. TREATMENT
 GENERAl MEASuRES:-
 Diet
 Physiotherapy
 Skeletal muscle weakness
 Prednisone (0.5-2mg/kg/day)
 Methotrexate,Azathioprine,Cyclophosphamide,Cyclospor
ine,Mycophenolate mofetil,Leflunomide,Chlorambucil

20. TREATEMENT OF SKIN DISEASES
FIRST lINE THERAPY
 Sun avoidance
 Sun protection measures
 Hydroxychloroquine/chloroquine
 Methotrexate is fist line therapy if anti malarial are
contraindicated
 Consultation