This woman's proximal muscle weakness (pelvic and shoulder girdle), erythematous, slightly scaly papules on the extensor surfaces of the hands (Gottron papules), and facial rash make dermatomyositis the most likely diagnosis.
This patient presents with symptoms of dermatomyositis. The condition is associated with an increased risk of certain malignancies, the reasons for which are not yet fully understood. Ovarian cancer, which characteristically shows elevated serum CA-125 levels, is the most commonly reported malignancy alongside gastric cancer and lymphoma. Since ovarian cancer can remain asymptomatic until reaching advanced disease stages, it may well have developed in this patient.