My son has a lump in his breast right behind the nipple. We were told it is nothing to worry about, that it is normal in 12- to 14-year-old boys. Is normal this breast development?
Breast development in boys
Your son is not alone. Fully 60-70% of male teens experience breast enlargement (gynecomastia) between 12-15 years of age.
Breast tissue grows whenever the ratio of the body’s estrogen is increased relative to the body’s androgen. Although estrogen is thought of as the female hormone and androgen the male hormone, males and females have both in differing amounts.
Early in a boy’s pubertal development, he has not yet experienced much androgen secretion. Because he has relatively more estrogen present in his body, one or both breasts may be stimulated to enlarge. The breast enlargement disappears spontaneously within 6-24 months.
Less commonly, medical conditions such as tumors, thyroid disease and marijuana or heroin abuse can cause pathologic male breast enlargement.