A 58-year-old-woman presented with a 2 month history of progressive asymmetrical extrapyramidal symptoms and signs predominantly affecting her right side, suggestive of Parkinson's disease. Specifically, she had a pill-rolling resting tremor in conjunction with bradykinesia and cogwheel rigidity of her right upper limb. A Brain MRI was performed (Figure 1) and demonstrated a large contrast-enhancing lesion most suggestive of: