Juvenile Dermatomyositis

INTRODUCTION

Siti is a 12-year-old Malay girl presenting with a one week-history of episodic pain on the inner thighs of both legs.

HISTORY

Presenting complaint

The pain is of a dull, cramping nature and is worse at night, disturbing her sleep. She is able to walk and perform her daily activities without much interference from the pain. There is discharging wound on her right knee of 2-weeks duration. She also had lethargy and loss of appetite over the same period.

She has no fever, chest pain, haematuria, shortness of breath, abdominal pain, joint pain or swallowing difficulties.

Past history

Siti had a past history of juvenile dermatomyositis first diagnosed at 6 years of age and since then she had multiple admissions for flare of dermatomyositis of which the last admission was on 12 June 2002.

Present problems

1.            Photosensitive rash: She first presented with photosensitive rash at 6 years of age, not associated with vesicles or fever. The rash improved after oral prednisolone and sun-block cream.

2.         Bilateral limb weakness:

�         First started at 9 years of age.

�         Difficulty in climbing stairs and walking to school.

�         Required uncle to help her carry school bag and bring her to school on bicycle.

�         No bladder or bowel symptoms.

�         No headache or sensorial changes.

�         Speech and swallowing are not affected.

3.         Arthritis and arthralgia:

�         Developed bilateral knee pain, stiffness and mild swelling.

�         Also has neck and backache.

4.         Infected calcinosis: She has multiple calcinosis, especially over her lower limbs and had several hospital admissions for infected calcinosis requiring IV antibiotics.

Family

There is no family history of connective tissue or skin disorders.

Siti�s father deserted her family when she was 3 years of age and her mother remarried 2 years later. She has four younger siblings � one 8-year-old sister and three 11, 6 and 3 year old brothers. She lives with her stepfather, mother and siblings in a three-room HDB flat at Circuit Road. She lives on the 12th floor and there is a lift to her floor. She requires financial and social support. She had missed school for several days and has not been taking part in outdoor activities.

Treatment

She is currently on:

�         Prednisolone with ranitidine and methotrexate.

�         Betnovate cream to face.

�         Aqueous cream to dry skin areas.

�         Physiotherapy to improve muscle strength.

CLINICAL EXAMINATION

General inspection

Siti is alert, comfortable at rest and able to respond to speech in full sentences. There is mild dysphonia, but there is no dysphagia or difficulties in articulation.

Her face is cushingoid and there is a heliotrope rash over both eyelids and malar facial rash.

There is a generalized rash over the extensor surfaces of both upper limbs, chest, neck and back. The rash is scaly and erythematous in some areas interspersed with areas of hypopigmentation.

Parameters

Her parameters are below the 10th percentile of her age group.

Vital signs

Her vital signs are stable.

Upper limb

There are Gottron papules over the metacarpophalangeal joints and the proximal phalangeal joints. There is synovial thickening over small joints of the hands. There are no deformities or joint contractures.

On palpation, the skin areas with the rash are warmer than those without. There is no tenderness or loss of function.

She is able to write, brush teeth, comb hair, turn taps on or off, feed and wash herself.

Lower limb

There are subcutaneous calcium deposits on the right knee beneath the discharging wound. There is synovial thickening over small joints of the knees. There are no deformities or joint contractures. There is tenderness over the inner thighs of both limbs. There is no loss of function. The gait is normal.

Complications of Steroid toxicity

�         Cushingoid facies.

�         Buffalo-hump, posterior scapular fatpads.

�         No abdominal striae, easy bruising, ecchymoses.

�         Paper-thin skin over the extensor surface of upper limb.

�         Proximal myopathy not present.

�         No hypertension.

�         No palpable liver.

SUMMARY

Siti is a 12-year-old Malay girl with a past history of juvenile dermatomyositis, now presenting with tenderness over the inner thigh of both lower limbs and a discharging wound on the right knee. She is otherwise well with no limitation of joint movement or impairment of daily activities.

QUESTIONS

What are the diagnostic criteria of juvenile dermatomyositis?

�         Gottron papules, scaly red papular areas over the knuckles (metacarpophalangeal joints) and interphalangeal joints.

�         Heliotrope rash, a violaceous or purplish edematous discoloration around the eyes, particularly around the eyelids, it may cross the nasal bridge and include the nasolabial folds.

�         Other rashes: scaly red rash on the face, neck and upper chest (V-sign), the shawl area and over the extensor tendons, particularly of the hands.

�         Symmetrical proximal muscle weakness.

�         Elevated muscle-derived enzymes.

�         Muscle histopathology confirming chronic inflammation.

�         EMG changes of inflammatory myopathy.

What are the other complications of juvenile dermatomyositis?

�         GI: impaired speech from tongue involvement, decreased esophageal motility with impaired swallowing, esophageal reflux, aspiration pneumonia, ulceration, perforation, haemorrhage and malabsorption.

�         Respiratory: pulmonary fibrosis.

�         Vasculitis involving CNS.

�         Retinopathy: retinal exudates, optic atrophy, visual impairment.

�         Renal failure secondary to myoglobinuria from muscle breakdown.

What are the medications used in the management of juvenile dermatomyositis?

�         First-line: prednisolone.

�         Second-line: azathioprine, methotrexate, cyclosporin, cyclophosphamide. IVIG.

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