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 onset

Muscle disease may occur- Concurrently, Precede the skin disease, or Follow the skin disease by weeks to years.

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

SKIN RASH IN DERMATOMYOSITIS

Heliotrope rash

-violaceous colour-Periorbital edema present

SKIN RASH OF DERMATOMYOSITIS

Gottrone’s papules

Involves the dorsal surface of MCP and IP joints

SKIN RASH OF DERMATOMYOSITIS

Periungual telengiectasia

SKIN RASH OF DERMATOMYOSITIS

Rash in Shawl distribution

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

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

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 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 polymyositis

1. 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 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

HOW WILL YOU INVESTIGATE

Enzymes – 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 2

Source: The Lancet 2003; 362:971-982 (DOI:10.1016/S0140-6736(03)14368-1)

Terms and Conditions

HISTOPATHOLOGICAL FINDINGS OF DERMATOMYOSITIS & POLY MYOSITIS

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.

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

TREATMENT

For skin component

Hydroxychloroquine

Topical steroids

sunprotection

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

USEFUL LINKS

http://www.aafp.org/afp/2001/1101/p1565.pdf

http://emedicine.medscape.com/article/332783

The value of experience is not in seeing much, but in seeing wisely.

SIR WILLIAM OSLER

Thank you all