Post-mastectomy underarm boob?

@kabash since my lumpectomy (May 2019) I have had a more prominent swollen underarm when I raise my arm. Not a lump so much as a swollen area which stuck out a bit. The underarm goes out instead of in. I had a lymphodema massage before Christmas (preemptive, I don't have signs of lymphoedema) and the therapist suggested it might be a seroma. I swam in the sea a lot the last few weeks using my arms to swim over the waves, quite physical, and I think it has gone down a little and I'm hoping it will resolve by itself. That area was radiated in November and perhaps that has affected it too. Good luck with yours. Thanks for posting as I've been wondering if my thing was common.

Today I saw the surgeon and a breast care nurse and they seemed to think that I have a seroma extending right along the scar line. There was also a small dehiscence in the middle of the scar. I forgot to ask whether it is likely that the underarm lump will remain as I was a bit distracted by the small wound opening and by learning that the pathology results weren't quite what I had hoped. I only had tiny viable tumours in the breast (3.5mm) and in one lymph node (1mm) (5/28 had looked like they had been previously cancerous/enlarged). So now I have to see the oncologist tomorrow for a review and some Herceptin and also get the seromas drained on Friday. Considering my diagnosis of inflammatory breast cancer spread over an 8cm area across the whole boob I should be grateful that my response to the treatment was good. However I was hoping that the doc would say the magic words pathological complete response. It was not to be. I came so close!

So now maybe I will need to have more chemo or Kadcyla, and as it is not on the PBS, it might be very costly if I have to do it privately. I will have to raise the underarm boob question again when I have my next surgical review next week, when hopefully it will be clear whether it is fat or fluid. Thanks for all the advice and help.

I didn't feel particularly fat shamed by the nurses when they said I was a bit overweight, as it is true and I felt they were just being matter of fact about it. However I do remember once being told by a doctor that I was obese, when I was much lighter than I am today (around 70kg). On that occasion I did feel fat shamed, mostly because she seemed kind of disgusted by my slightly overweight frame.

I had a roll of fat under my arm after right sided mastectomy, because the weight of my removed breast was no longer there to pull it forward. It was uncomfortable because it was just where the top side part of my bra sat, so it couldn't decide if it wanted to stay in or out, especially if I lifted my arm. So I had a scar revision about 2 years after the mastectomy, and feel much more comfortable now, although it did mean the scar was extended a bit further around towards my back to give a smoother transition. I was told this would happen.
It is early days for you, and yours might be swelling, fluid, or fat (fat is not a dirty word, we've all got it!).
Good luck with your recovery.

Yep. Mine varies according to my weight, but they usually look like half a cup of soft butter in a sandwich bag. Attractive. Not. Noone has every offered to do anything about them.
It's worth keeping an eye on that armpit though, seroma are a nuisance and can appear to be fatty lumps when they are actually collections of fluid. If anything changes get your breast care nurse to have a look.

Yep. I had implant reconstruction but still have this as the breast doesn't drag it forward. 
I am having a different type of reconstruction in the future now and they will address this for me. It is very uncomfortable I have to drag it physically forward in the bra. 
Sometimes referred to as dog ears I believe.
They said some liposuction or possibly extending the scar  and remove more tissue could resolve this for me. Mine remains there even 2 kg above healthy bmi but much worse when I gain. It's my leftover of huge boobs and not related just to weight. It's particularly a pain in really hot weather.

Post-mastectomy fat shaming is surely a new low in medical care???? I hope they fix it for you @kabash

It’s most likely swelling. Also a little fat under the arm can look different after a mastectomy and axillary clearance, doesn’t quite fit the same way. The other possibility is a seroma, fluid accumulation (your body trying to assist, just like fluid forms on a blister if you scrape your heel). The latter is usually easy to determine and will usually disperse of its own accord. Your surgeon knows about it; if it continues for too long, just give her another nudge! Best wishes.

I had this and my PS did some liposuction when he did some revision surgery.  Do bare in mind that you're not long after having surgery and it could all just be swelling.