E.W.
Hi R.,
I had my first mammogram at 16. I, too, felt a large lump in my breast. I hid it for a long time because I was so young and so scared. And then one night I had some discharge (or what I thought was discharge). I really got scared and told my mom right away. She took me to a doctor and I had my mammogram. It did prove to be a fibroid cyst and one that didn't cause any concern from the doctor. Mine was so big that it caused a difference in the size of my breasts. I ended up getting implants to make up for that but never had the cyst removed because my doctor didn't see it as necessary. It does get sensitive and tender at times. I just continue to do an exam myself and also by my doctor.
It can be such a scary thing. Mammograms are not that pleasant either (as it squishes you in a spot that is already tender!) But I am glad she is going to get it checked out. That is the most important thing for her health and her psyche. I have heard that lumps that might be more suspicious are almost like little pebbles or rocks. My cyst was softer.
I wish you and your sister luck. Let me know if you have anymore questions.