Recent Left Mastectomy, Lump Under Right Arm Pit

I’ve woken up this morning with a lump under my right arm pit, which I feel a bit panicked about. Just over two weeks ago I had a left sided mastectomy and still recovering from that. In addition to this I am waiting for my breast sample to come back from being oncotyped to see if I need chemotherapy on top of radiotherapy and tamoxifen. 


Any ideas or advise on what the lump could be? I’m going to give it until tomorrow and will probably go to my GP x

Hi Sunflower

It’s not something I’ve experienced, so I can’t help in that respect. But I would say give your bc nurse/team a call, as they will have more of an idea than your gp.

Hugs xx 

I agree the specialist breast care nurse would be able to advise you about this Sunflower.


I’ve not had a mastectomy but even with the 2 wounds I have on the right breast and arm pit, my left breast is coming out in sympathy with twinges and similar sensations, bless em.


Hope you find everything is ok, do let us know what the nurse says and how you get on.


Luv n Hugs :heart:



Hi Sunflower, it could be a number of things related to the surgery, but not the cancer. Best get it checked ASAP. The hospital where the surgery was done would be best, as if there’s anything surgery related you are in the best place straight away. Have you a BC nurse you can phone? Hope it’s sorted soon. X

Hi Sunflower, 


As others have said, best to get it checked out with your specialist nurse, but it could be a seroma, which I was warned about before my surgery. I’ve had a double mastectomy (3 weeks ago) and developed a number of large areas of seroma. A seroma’s a collection of serous fluid (healing fluid, like the fluid you get in a large blister) which can collect under and around the wound after a mastectomy. It’s harmless though, and it usually starts to develop about a week after surgery bif you develop it. Your body gradually reabsorbs it over 4-6 weeks, but a specialist nurse/surgeon can drain it if it becomes troublesome.


Mine’s now starting to go down a bit, but at its worst it looked as though my breasts were growing back!! :smileysurprised:  Fortunately my surgeon warned me I was at a higher risk of developing a seroma before my op, so when it started I knew what it was. Though it’s going down slowly but surely now, I still have a number of large collections of it around my chest, and I have still a large collection of it, which looks like a lump, just above the end of my wound in my arm pit.