Sad and serious news. I've talke about my cat a little bit, and how she was found by me when she was a disabled, malnourished kitten, she would have died if I found her a day later. I had to hand feed her to give her strength. I had no cat food so for until she was up to weight she was eating human quality tuna and raw steak slices.
She has developed a large cyst, it happened quickly, after it didn't go away for a week I asked for help irl with getting her an appointment. She has one now. Her spirits are high even though she has a limp, and the cyst has opened up and hair has started falling out. The worry is cancer, but hopefully it isn't and is something she will recover from. I'm sorry if this bummed anybody out.
And I can't stop worrying if it was something in the area that gave her the cancer, if that's what it is. Something in the air, water or ground.