Worried about lump under armpit. I was recently diagnosed with the chek2 gene mutation

[Serene1974]

The golf ball size lump has been there for at least 4 months. I just thought I was getting fat and I was getting fat under my arm pit. It feels hard and doesn’t move. I’m very worried. I have an appointment with GP on Tuesday

Has anyone had a lump like this? If so what was it? Everything I’m reading on google says it’s probably cancer because it’s hard and has been there for at least 4 months.

Hi just wondered if you found out what this was as I have something similar 😟