I was sent home for the weekend. The biopsy was planned for the coming Monday (27th of February). Since I was feeling fine, and nothing medical was happening during the weekend, I could leave and come back Sunday evening.
Over the weekend I had some more time to think and discuss the situation. I started to doubt about the biopsy. Maybe waiting, a follow-up scan, and perhaps a lumbar puncture, would be a less risky approach. I was feeling fine, and what are the chances for this situation. It felt like an unlikely presentation of MS was still more likely than a very rare type of cancer.