A 26-year-old man presented to the emergency department after having a five-minute tonic-clonic seizure. He was postictal for less than one hour and then returned to his baseline. Over the previous two days, he had experienced a mild diffuse headache and an intermittent blind spot in the center of his vision. For the previous three weeks, he had noticed left upper extremity weakness and dexterity issues in his left hand occurring after intense sessions of upper extremity weight lifting. He also reported having a lesion on his back that had been slowly growing for more than one year and occasionally bled. Otherwise, the patient appeared healthy. He had no history of recent travel.

Physical examination confirmed left upper extremity weakness and impaired fine motor skills of the fingers. The patient had normal heart sounds. The remainder of the neurologic examination was unremarkable. Magnetic resonance imaging (MRI) of the brain was performed (Figure 1). A pedunculated lesion measuring 4.0 × 3.5 × 1.5 cm (Figure 2) was found on his left upper back.

Question

Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?