Thanks to all that commented. I was surprised at the level of interest. Your creative suggestions made me laugh, which is exactly as I would have expected on this Forum.
The medical people knew exactly what it was they were removing, quite rare apparently and with a long name difficult to remember or even pronounce. I can imagine the plastic surgeons queuing up to get it on their bucket list, or at least their C.V.
It started in Nov'21 when I had a blood sample taken. The wound bled and needed a small dressing. The following morning a lump started to grow and kept on growing at quite a pace. By the time of the operation, it was 2" long across the width of my arm and stuck up. It was like having a third testicle, but in a place more prone to impact. I don't normally care what anyone else thinks except for friends and family, but I became self-conscious about it and started wearing long sleeved shirts in the Summer, or some tape that my grandson wears to secure his diabetes kit to his arm while he's playing rugby. Yes, I know there will be a scar, but I'd rather have a scar that when people see it, they recognise it as a scar and instantly dismiss it. Nothing to see here! But an angry looking red lump catches their eye and they can't help but look to see if they can tell what it is. My mature adult brain says to let them look, but for reasons I can't explain (maybe it's the childish part, deep inside my monkey brain), it unsettled me, so I covered it up.
By the time of the operation, I had seen two skin consultants, a vascular surgeon, and two plastic surgeons. Along the way, I'd had three ultra sound scans and a 6mm punch biopsy. And yes, that is a 6mm diameter punch driven into the lump to take a core sample, which is why they know exactly what it was. Then after an intervention by my GP, who felt that I had waited long enough, I had to go for a pre-operation assessment, to see if I was fit enough for an operation under a general anaesthetic. I passed everything except the ECG that said that I had a problem with my heart! (!!!!!). They suspected a Left Branch Bundle Block. I had no symptoms but it was still a worry. It took 2 months to get the echo-cardiogram (a sort of ultra sound scan) of my heart. And another six weeks to get the result. Absolutely clear! Nothing wrong with my heart, absolutely normal. Joy unconfined.
Anyway, after all of this hanging about, I now have an interesting scar, know for certain that my heart is 100% healthy, my blood pressure is an almost unwavering 125/80 (+/- 2 or so) and my SPO2 (blood oxygen level) is a healthy 96-100%, not bad for 73!
Once I've had the stitches out in a week or so, I'll be ready to start falling off my bike again. Can't wait!