This document discusses muscle weakness and skin rash (dermatomyositis). It provides information on the clinical presentation, causes, diagnostic criteria and classification, investigations, histopathological findings, treatment and prognosis of dermatomyositis. Key points include that dermatomyositis involves proximal muscle weakness and a skin rash. Diagnosis involves elevated muscle enzymes, electromyography, muscle biopsy and the presence of a skin rash. Treatment primarily involves oral steroids. Prognosis depends on factors like age, presence of malignancy and disease recalcitrance.

1. MUSCLE WEAKNESS & SKIN RASH
( DERMATOMYOSITIS )
Dr. Mohammad Tanvir Islam
Assistant Professor , Dept of Medicine
Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh

2. 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

3. WHAT MAY BE THE CAUSE OF THIS MYOPATHY
 Inflammatory myopathy
 Drug induced
 Endocrine
 Infection
 Alcohol

4. MYOPATHY WITH SKIN RASH
 Dermatomyositis
 Steroid induced myopathy
 Hypothyroidism
 Other CTDs

5. DERMATOMYOSITIS
 Double peak of onset
 Average age of onset is 40
 In 40% individuals the skin disease is the sole
manifestation at onset
Muscle disease may occur-
 Concurrently,
 Precede the skin disease, or
 Follow the skin disease by weeks to years.

6. CLINICAL PRESENTATION
 Proximal myopathy
 Skin rash
 Systemic features-
 fever, malaise , arthralgia, arthritis, dyspnea,
dysphagia, arrhythmia, and dysphonia,
raynauds.
 Malignancy- lungs, GI tract, breast, overy etc

7. Heliotrope rash
-violaceous colour
-Periorbital edema
present
SKIN RASH IN DERMATOMYOSITIS

8. Gottrone’s papules
Involves the dorsal surface of MCP and IP joints
SKIN RASH OF DERMATOMYOSITIS

9. Periungual telengiectasia
SKIN RASH OF DERMATOMYOSITIS

10. Rash in Shawl distribution
SKIN RASH OF DERMATOMYOSITIS

11. COMPLICATIONS
Dermatomyositis & 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

12. COMPLICATIONS
 Cardiomyopathy & Cardiac conduction
defects
 Aspiration pneumonia
 Diffuse interstitial pneumonitis/fibrosis
 Large-bowel infarction
 Muscle atrophy & Muscle calcification
 Ocular complications including iritis,
nystagmus, cotton-wool spots, optic atrophy,
conjunctival, edema and pseudopolyposis

13. CLASSIFICATION CRITERIA FOR POLYMYOSITIS
AND 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 knees
2. Proximal muscle weakness (upper or lower extremity and trunk)
3. Elevated serum creatine kinase or aldolase level
4. Muscle pain on grasping or spontaneous pain
5. 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 arthralgias
8. 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)

14. CLINICAL CRITERIA
 1975, Bohan and Pete
 Set of 5 criteria to aid in the diagnosis and
classification of dermatomyositis
and polymyositis
1. progressive proximal symmetrical weakness,
2. elevated levels of muscle enzymes,
3. an abnormal finding on electromyography,
4. an abnormal finding on muscle biopsy
5. Cutaneous disease.

15. SUBSETS OF MYOSITIS
Bohan 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

16. HOW WILL YOU INVESTIGATE
Enzymes –
 CK
 Aldolase
 LDH
 carbonic anhydrase isoenzyme III

17. 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

18. 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

19. 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.

20. Figure 2
A, B: Depletion of capillaries
in dermatomyositis (A) with
dilatation of the lumen of the
remaining capillaries,
compared with a normal
muscle (B). C: Perifascular
atrophy in dermatomyositis.
D: Endomysial inflammation
in polymyositis and inclusion-
body myositis with
lymphocytic cells invading
healthy fibres. E: The MHC-
I/CD8 complex in polymyositis
and 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

21. 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

22. TREATMENT
 Other drugs used- methotrexate,azathiprine,
cyclophosphamide, cyclosporine
 IV immunoglobulin for refractory cases
 Physiotherapy

23. TREATMENT
For skin component
 Hydroxychloroquine
 Topical steroids
 sunprotection

24. 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

25. USEFUL LINKS
 http://www.aafp.org/afp/2001/1101/p1565.pdf
 http://emedicine.medscape.com/article/332783

26. The value of experience is not in seeing
much, but in seeing wisely.
SIR WILLIAM OSLER

27. Thank you all