New Double Vision and Cancer History

A 72-year-old woman was referred to neurology due to a six-week history of double vision. Additionally, over the last couple of weeks, she has experienced pain behind her right eye, with associated painful eye movements and right eyelid swelling. The patient also reported weight loss of 6 kg in the last 3 months, as well as heavier breathing even at rest. Blood tests revealed microcytic anemia, but thyroid function was normal. The patient had a previous history of breast cancer, but she had been in long-term remission for over 10 years. Upon admission, a chest X-ray showed bilateral pleural effusions.