History
A 59-year-old woman visited her GP as she was concerned about unexplained weight loss. Her GP noted an erythematous rash around her eyes and over the dorsum of her hands and referred her to the dermatology clinic. On direct questioning she does com-plain about difficulty in getting up out of a chair and climbing the stairs. She denies any other symptoms apart from a persistent dry cough. She is a life-long smoker and drinks alcohol socially.
Examination
She has erythematous flattish papules over the extensor surfaces of her interphalangeal and metacarpal phalangeal joints (Fig. 38.1). In the periorbital region she has a violaceous erythema with subtle oedema (Fig. 38.2). There is an erythematous non-scaly macular rash affecting her neck and upper back. Neurological examination reveals proximal limb weakness.
Questions
• What is the cutaneous diagnosis?
• What may be the underlying condition?
• How should this patient be managed?
Medicine
The cutaneous manifestations of this disease may be striking or more subtle; therefore a high index of clinical suspicion is needed to make the diagnosis of dermatomyositis.
The erythematous, purplish, flat papules over the extensor surfaces of the interphalangeal joints are termed Gottron’s papules and are pathognomonic of dermatomyositis. The peri-orbital heliotrope rash with associated oedema is also highly suggestive of the diagnosis.
Erythema around the posterior and ‘V’ of the neck is the so-called Shawl’s sign. Periungal erythema with telangiectasia may also be classically seen.
Muscle involvement is usually manifest by muscle tenderness and weakness with a proxi-mal myopathy. Patients will describe difficulty rising from a supine position, climbing the stairs or combing their hair. In some cases muscle involvement of the bulbar, pharyn-geal and oesophageal areas can occur leading to difficulty in breathing and swallowing.
Muscle involvement may precede, follow or occur simultaneously with cutaneous disease.
Dermatomyositis is rare and the cause remains unknown. However, a high proportion of affected patients over the age of 50 years had an associated underlying malignancy. This patient was a smoker with weight loss and, following further investigations, was diag-nosed with a carcinoma of the bronchus. The most common types of malignancies asso-ciated with dermatomyositis involve the ovary, breast, lung and gastrointestinal tract.
A skin biopsy may be helpful but histopathology is not specific to dermatomyositis.
Raised muscle enzymes are typically seen including creatine kinase and lactate dehydro-genase. Non-specific antinuclear antibodies (ANA) are found in most patients, specific anti-Mi-1 is found in around 25 per cent and anti-Jo-1 in just a few. An electromyogram of an affected muscle will generally be abnormal and biopsy of an affected muscle can also be helpful. Magnetic resonance imaging is often the preferred investigation, if avail-able, to show focal muscle involvement.
A moderate to high dose of oral corticosteroids is usually the initial therapy given. Steroid sparing agents used in the second line include methotrexate, azathioprine, ciclosporin, mycophenolate, cyclophosphamide and high-dose intravenous immunoglobulin. The prognosis in most patients is relatively good except in those with respiratory myopathy or with an underlying malignancy. A better prognosis is seen in individuals who receive early immunosuppression. Most patients will require treatment for life; however, in about 20 per cent of patients the condition abates. Patients are advised to avoid excessive sun exposure and to use photoprotective measures. Patients should be followed up and screened regularly for the possibility of underlying malignancy which may reveal itself in time.
KEY POINTS
• Gottron’s papules are pathognomonic of dermatomyositis.
• An underlying malignancy should be excluded in older patients.
• Early intervention with immunosuppression leads to a better prognosis.
need an explanation for this answer? contact us directly to get an explanation for this answer