Patient: 30-year-old female, 17 years ago, gradually developed walking pad, lumbar disc protrusion, weakness of limbs, difficulty in lifting, difficulty in squatting, walking like a duck, easy to fall, gastrocnemius hypertrophy, muscle pain, lumbago, cold, cold hands and feet, etc. 15 years ago, diagnosed with polymyositis, taking prednisone, inosine, calcium gluconate, B6, no significant effect, and then gave up treatment. Currently not taking any medication. Wang Qian: First of all, we need to identify whether it is myositis or myopathy. The onset of the disease is only 13 years old, the onset is slow, and the effect of treatment such as hormone is not good, so hereditary or congenital myopathy should be considered. It is recommended to first go to the neurology department to check for myopathy such as myotonic dystrophy (can have gastrocnemius pseudohypertrophy). If the hospital diagnosis is correct, chronic migratory myositis should be considered as a possibility. The principle of treatment for this disease is the slow reduction of large doses of hormones in adequate amounts and courses, with methotrexate being the preferred immunosuppressant. At that time, hormones (for at least 1 year) and methotrexate should be continued and the lungs should be screened. Considering the long duration of the disease and the development of muscle atrophy, recovery may be slow and requires patience and cooperation with rehabilitation therapy, not an acute illness. In addition if anti-SSA and anti-RNP antibodies are positive, a review is recommended and it is likely that other autoimmune diseases (such as systemic lupus erythematosus) are hidden behind the myositis.