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How are polymyositis and dermatomyositis associated with other autoimmune diseases?

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muscle disease The causative agent of tetanus, *Clostridium tetani*.

Polymyositis and dermatomyositis are inflammatory myopathies categorized as autoimmune diseases, meaning they result from the immune system attacking the body's own tissues.12

These conditions frequently occur in association with other autoimmune diseases, most notably rheumatoid arthritis and progressive systemic sclerosis. While the exact cause of the autoimmune reaction against striated muscle remains unknown, the presence of these overlapping conditions highlights the complex nature of systemic immune dysfunction in patients with inflammatory myopathies.1

Additionally, it is important to note that these diseases—particularly dermatomyositis—are sometimes associated with cancer. In a significant proportion of older patients, these conditions may manifest alongside malignancies, such as those of the lung, breast, or gastrointestinal tract, necessitating careful clinical evaluation.12