Mitch here, just reporting that Robyn's had the surgery and is recovering pretty well. Straight afterward she was looking a bit blue, but the methylene blue they inject to trace the lymph nodes will do that to you. It looks as though the worst (for a musician) hasn't happened, as she still has full sensation and control in her arm, so she's now looking forward with confidence to getting back into playing at the session and the Morris.
Thanks for all your good wishes - it's great to have a worldwide support group.