A 58-year-old woman is admitted to hospital with a history of general muscle weakness of 12 months’ duration.

A 58-year-old woman is admitted to hospital with a history of general muscle weakness of 12 months’ duration. She also gives a history of pain in the small joints of her hand, which she has
had for more than 18 months. In addition, there is a history of difficulty swallowing.
Examination is normal except for tenderness of her upper arms and swelling of the small joints of her hands.
Her erythrocyte sedimentation rate (ESR) is 60 mm in 1 hour, her haemoglobin is 9.5 g/dl, and
her mean corpuscular volume (MCV) and mean cell haemoglobin concentration (MCHC) are
normal. Serum antinuclear antibodies and rheumatoid factor are positive. Creatine kinase is also
raised.

What is the most likely diagnosis?

A. RA
B. Sjögren syndrome
C. Polymyalgia rheumatic
D. Mixed connective tissue disease
E. Polymyositis

Answer:
E--Polymyositis

Discussion: Polymyositis is a disorder of the muscles characterize by necrosis of muscle fibres, together with regeneration and inflammation.
Dermatomyositis is the name given to the condition when a rash accompanies polymyositis. This shows an increased incidence of carcinoma of the bronchus in men and of the ovary in women.

Clinical features: It presents with proximal muscle weakness and wasting. Muscle pain and tenderness can occur in up to 50% of patients, but weakness is the main symptom. Arthralgia
affecting the small joints of the hands can occur in about half of all patients, pre-dating the muscle
weakness. Dysphagia due to oesophageal muscle spasm occurs in up to 50%. Raynaud’s phenomenon is commonly seen.

Diagnosis: Muscle enzymes (creatine phosphokinase and aldolase) are raised and can be used to
monitor the disease. Electromyography (EMG) shows short polyphasic motor potentials,
spontaneous fibrillation and high-frequency repetitive discharges. Patients have a raised
erythrocyte sedimentation rate (ESR), a normocytic and normochromic anaemia, and positive
rheumatoid factor and antinuclear antibodies.

Treatment: Patients should be treated with prednisolone at a dose of 60 mg daily, reducing to a
smaller maintenance dose. Physiotherapy to restore muscle strength can be helpful.
Immunosuppressants such as methotrexate or azathioprine may be needed.