Will the hard lump left behind after hematoma improve or heal?

For this question - definitely check back in with your surgeon.  Most hematomas resolve within 2 months - but scar tissue can remain or even form.  I generally recommend massaging scar tissue - firmly, 5 minutes twice a day - if this is what it is.  But definitely get it checked out to make sure it is something simple!  Best of luck!

In general, hematoma that is left alone with eventually liquefy and be absorbed by the body.  In some cases the hematoma with lead to scar formation as you are describing.  With time these will usually resolve.  They can be encouraged with massaging of the area as well.However, if there is an implant associated with the hematoma things change.  If the hematoma is present in the implant pocket, when left alone could lead to capsular contracture.I would recommend following up with your plastic surgeon or with a board certified plastic surgeon to determine if you are developing capsular contracture.  If caught early enough, there are times that it can be prevented from getting worse and in some cases can be reversed.Hope that helps.

I highly recommend that you see your surgeon and have him assess this in person.  This may be scar tissue, fat necrosis or even the start of a capsule so make sure you see your surgeon soon.