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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 67-year-old man with lung cancer notices symptoms of weakness in his arms and legs. He describes difficulty in rising out of chair or going upstairs, but no pain or discomfort. On examination, proximal muscle strength is 4 out of 5 in the upper and lower limbs, but the reflexes, tone, and sensation are normal. He has a colored rash on his eyelids, and raised papules on his knuckles.For the above patient with muscle weakness, select the most likely anatomic site for the disorder.
assistant
The correct answer is  Dermatomyositis is one of the inflammatory myopathies that has a characteristic rash on the eyelids (heliotrope) and knuckles (Gottron papules). It is associated with certain cancers as a paraneoplastic syndrome. The muscle enzyme creatine kinase (CK) is elevated is most cases, but the condition is painless. Symptoms are those of proximal muscle weakness, with normal reflexes and tone on examination.