So what could that lump be?  The most common type of lump found in teens is called a fibroadenoma.  Usually a fibroadenoma is smooth and hard and can move around easily.  It is not cancer, but you will need to let a doctor examine you to see if it needs to be biopsied or removed, just to be sure.

You might have a cyst, a fluid-filled sac in the breast tissue.  Cysts may come and go with a woman’s menstrual cycle.  They are not dangerous, but if they get too large or painful, a doctor can drain the fluid.

If you have found a lump in your breast, it is safe to wait for a month to see if it goes away or changes over the course of your menstrual cycle.  However, if you have a lump that doesn’t change or gets larger, contact a doctor to find out what type it is.  Don’t panic.  Worry doesn’t help anyone, and the odds that your problem is dangerous are very small.

Part of growing up is becoming responsible for your own health, so it’s a good idea to notice how your breasts feel at different times of the month.  Check them out in a mirror, and pay attention to how they feel when you shower.  If you notice changes that concern you, let your mother, the school nurse, or another adult know.  She can help you decide if this problem needs a doctor’s attention.

You may want to read more about puberty.  Here are a few books I found helpful when I was writing this article.

The What’s Happening to My Body? Book for Girls:  A Growing Up Guide for Parents and Daughters by Lynda Madaras with Area Madaras.  This book has complete information about all aspects of puberty.  Although the focus is on girls, it also includes information about what the boys are going through.

Body Drama by Nancy Amanda Redd.  This book is organized by questions girls have about the changes in their bodies.  If you wonder whether your breasts look “normal,” you’ll find photos of real girls, real breasts and other body parts in all shapes, sizes and colors so that you can see how wide the range of “normal” is.

Dr. Susan Love’s Breast Book by Susan M. Love, with Karen Lindsey.  This is a big, thick book, and most of it is about breast cancer, but there are also excellent sections on normal breast development and about non-cancerous problems that women may have.

The Center for Young Women’s Health at Children’s Hospital in Boston has an excellent website with information about all aspects of teen health.  Check them out at http://www.youngwomenshealth.org.