Case vignette

A 52-year-old man with hepatitis C and a remote history of recreational drug abuse presents with several days of shortness of breath, cough and malaise. He was seen at an outside hospital and diagnosed with pneumonia given his cough and shortness of breath. Subsequently, he was seen again and found to have a small abscess of his arm that was drained. On review of systems, he endorses nausea and generalised weakness but denies abdominal pain, chest pain, numbness, fever, headache or dizziness. On physical exam, he is afebrile but tachypnoeic, has decreased breath sounds at the bases, and has an appropriately healing incision site. Neurologically, he had drooping eyelids, decreased ability to adduct his right eye, blurred vision, a normal sensory exam and 4/5 diffuse muscle strength. He may have had worse proximal muscle strength, but this was difficult to distinguish due to poor effort.

Key questions

1. What is the differential diagnosis for this patient?

2. How should this patient be evaluated? …