breast hematoma

I was standing at my sink doing dishes and felt a sharp pain in my right breast. This was 2 days ago. The pain left as fast as it came and I really didnt think much else about it. About 30 minutes later I was changing my clothes, and noticed that there was a lump the size of a large egg in my right breast and was turning blue on the skin. My doctor said it was a hematoma. I had been on a baby aspirin once a day for the past month (I had been off the asa for a month due to having knee surgery)and just recently went back on it. He took me off the aspirin and told me to put ice on it. There has been no injury of anykind to that breast. What can cause a spontaneous hematoma like that? Now the entire top of my breast is purple and blue with a lump the size of a quarter and there is more discomfort in the area of the lump. Any information would be greatly appreciated. Thank you.

[CCF-RN,MSN-rf]

Dear kitten:  Hematomas (blood filled pockets) usually occur with some type of injury or even occassionally with biopsy or other surgery.  It is possible that there may be a weak blood vessel within the breast that may have even been bumped without notice.  The aspirin, being a blood thinner, could have made a tiny bit of bleeding more exagerated causing the large bruise you see now.  Of course, without evaluation, we cannot say whether this is the case.  A lump needs evaluation by a physician.  Sometimes ultrasound may be recommended as part of the evaluation to determine the nature of the lump.  If it is a hematoma, these can take months to resolve.