Dealing with fairly big pouch under armpit post-mastectomy?

A family member of mine has had a mastectomy after being diagnosed with breast cancer. It has been two weeks since the operation and she has a fairly large pouch which has appeared on the side of her body, under the armpit, on the same side as where the breast was removed. It’s causing her considerable discomfort and is not reducing in size. It feels soft. It is about 10cm long vertically and protruding 5cm horizontally from where her skin would normally rest. We have been to see her breast cancer doctor and nurse, and they say there is nothing they can do about it. They say that this is not the common build-up of fluid which occurs after such a treatment and so can’t be drained. (She has been drained where her operation was, in the breast area, and about 200ml of fluid came out a few days ago.) I have not come across other patients having such pouches appear in the tens of thousands of words I’ve read about breast cancer and mastectomies. Does anybody know such a pouch appearing under the armpit area and what can be done about it please? Thank you very much. I appreciate your advice.

Hi, At first I thought it may be a Seroma which is a build up of fluid which can either re-absorb itself or be drained (according to the opinion of the surgeon etc). But if they say it is not that it could just be an area of baggy skin. I have something similar and although I had my mx almost a year ago it has just appeared recently. My consultant said it could just be swelling (like the onset of lymphodema)… Does she also have any swelling on her arm at all - it may not be really noticeable, but measure both arms in several places and you can easily see a difference of an inch in places. Did she have her lymph nodes removed too? Mine feels as if I have a wad of material stuck under my arm/side at times - can you ask her if this also feels like that? I am seeing my surgeon again tmrw, so if I get a positive answer I will get back to you. In the meantime, if you want to PM me about anything please do so (just click on my user name to send a private message). It is very early days since her op and things will still be settling down. If it persists I think they can do a tidy up op to remove the surplus skin, but as it hasn’t been very long they will not offer this at the moment. Hopes this help a little bit