The question of removal versus biopsy only would be one to ask your Surgeon. I'm guessing you either have an appointment with a Breast Surgeon or will make one soon. He/She will review your films and advise as to the type of biopsy and also if total removal of the nodule would be appropriate at that time. A biopsy is the ONLY way to differentiate between malignant and benign. Regards..
Hi there.
The usual protocol for this is to have a needle biopsy, but it is also perfectly reasonable to pursue a complete surgical excision of the nodule if you and your surgeon are amenable to it. Just remember that surgical excision has its risks and side effects, depending on the amount of tissue to be removed, but these complications can be minimized depending on the expertise of your doctor/surgeon.
Regarding the probability of malignancy, it is indeed very hard to tell through ultrasound. The mammogram reporting in terms of BIRADS can help us with determining this probability. The BIRADS score is a standardized reporting system and I think you should ask your radiologist about this (http://biradsclass.blogspot.com).
Regards.