Elderly female with rash, limb muscle weakness for 1 month, dysphagia, and chest tightness for half a month. Physical examination reveals violaceous eyelid plaques with periorbital edema, coarse breath sounds in both lungs, fine rales in lower lungs, tenderness in left hand 2nd and 4th PIP joints, muscle strength grade 3 in upper limbs, and grade 2 in lower limbs. Based on analysis, the preliminary diagnosis is: