Complications
May complicate long-term corticosteroid treatment. Prophylaxis with calcium and vitamin D supplementation is recommended.
May complicate long-term corticosteroid administration, resulting in progressive muscle weakness, typically after an initial improvement in muscle strength. Normal creatine kinase levels and an absence of muscle irritability on needle EMG favor corticosteroid myopathy (a type 2 fiber myopathy) over myositis relapse.
May complicate long-term corticosteroid treatment. Initial fasting blood glucose and regular blood glucose levels are recommended prior to starting corticosteroid therapy.
Serious routine and opportunistic infections and septicemia from bacterial and fungal agents may complicate the course of immunosuppressive therapies. Early antibiotic or antifungal therapy should be initiated. Prophylaxis with trimethoprim/sulfamethoxazole or pentamidine to prevent Pneumocystis jiroveci infection should be considered in patients receiving moderate- to high-dose corticosteroids and who are heavily immunosuppressed.
Arrhythmias and cardiomyopathies may complicate idiopathic inflammatory myopathy.[87] The patient may present with shortness of breath, syncope, or respiratory failure. ECG and cardiac ultrasound are key tests to detect these conditions.
Interstitial lung disease may occur, especially in patients with anti-MDA5 and antisynthetase syndrome-related antibodies. Of note, anti-MDA5 positivity is associated with highly lethal rapidly progressive interstitial lung disease.
Risk for malignancy in patients with idiopathic inflammatory myopathy (IIM) depends on IIM subtype, presence of high-risk MSAs (specifically anti-TIF1 gamma and anti-NXPs), and age of onset of IIM.[74]
There is also variation in the associated malignancies depending on sex and geographic location.
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