Could 13 year old boys develop breast cancer?

Not likely at all: Although possible, breast cancer is rare in premenopausal women, and it is extremely, extremely rare in teenagers. In a teenage girl, a breast lump is more likely maturing breast tissue, or a benign mass. In addition, breast cancer is about 100 times less likely in men than women. If there is a concern, he should see his primary care physician.

Never heard of it: About 1/3 to 1/2 of males will undergo transient nipple or breast enlargement on one or both sides as they transition into puberty. It is a hormonal thing, not a cancer thing & usually fades within 6mo to a year. Rarely it can persist & require removal of breast tissue.A visit to the doc can confirm this.