Dr. Greene, my 12-year-old son has a sore lump directly under his nipple. Could this be puberty related? This lump is tiny and hard and underneath the skin of the nipple. Thanks for your help!

Lumps of one kind or another are a common reason for a visit to the doctor's office. The lump might be in the neck (that the parents suspect is just a swollen gland), in the knee (that the parents think is from sliding into third base last month), or under the nipple (that the parents hope is due to puberty). I often enjoy seeing parents with these concerns in my own office. Sometimes the parents feel that they shouldn't even bother their doctor with this because it's probably normal. But underneath these hopeful, at-home diagnoses lies a common fear--it might be a tumor!

Most lumps in children are not cancerous and are not serious. Thankfully, childhood cancer is uncommon. But parents' fears are not unfounded. Childhood breast cancer is quite rare, but it certainly does occur, even in boys. In males of all ages, breast cancer accounts for less than 1% of all cancers (American Surgeon, 1999; 65:250--253). But if it is your son, any chance of cancer seems too much. And a lump might be the first sign noticed.

Breast lumps in children often give rise to two immediate fears--Could it be a tumor? Or could something be going wrong with puberty? (A third fear--Will my child be teased?--arises if the first two turn out to be no problem.)

I'll give you some guidelines for when to be concerned about a breast lump and when you can relax.

Puberty is a time of dramatic changes in the body, especially in the reproductive system. These transformations are brought about by surges of complex and precisely balanced hormones. The last time your 12-year-old had these tides of hormones was when he was a newborn--but then the hormones were yours. Coursing through his blood, your hormones matured his lungs, made him ready for life in the big outside world, and along the way may have given him baby acne and breast enlargement--even nipples that leaked milk. This precious newborn season was gone in a blink.

Now your 12-year-old is making surges of these same hormones on his own as his body turns into an adult's--a miracle not unlike when you helped turn his body into a newborn's.

There are five stages of the changes that occur during puberty, called Tanner stages or Sexual Maturity Rating (SMR) stages. Breast lumps in boys are common during SMR 3 and SMR 4.

In boys, SMR 3 usually begins at about age 12 or 13 years and lasts a year or so, although it can be normal in our culture to begin as early as 10 years or as late as 14.9 years, according to Tanner (Journal of Pediatrics, 1985; 107:317). SMR 3 is the time when the testes get clearly larger, the penis gets noticeably longer (then thicker in SMR 4), and the pubic hair (though still small in amount) gets darker and starts to curl.

Sperm is first produced during SMR 3.

Boys grow at their fastest during SMR 3 and SMR 4 (girls get their growth spurts earlier). With your son, you're probably seeing him outgrow his beginning-of-the-year school clothes already--especially his shoes. During SMR 3, the feet and hands usually grow first, then the arms and legs, and finally the trunk--giving them that adorable adolescent gawky look (don't tell my 12-year-old son I said that).

SMR 3 also marks the beginning of significant underarm perspiration (the odor, as you've probably noticed, can start much earlier).

And teenage acne usually begins at SMR 3, continuing on until the end of puberty.

In newborns, baby acne and breast buds often occur at about the same time.