Nipple pain during puberty is generally likely due to unstable hormone levels in the body, causing a condition called gynecomastia in males. Gynecomastia is caused by hormonal stimulation, and any factors that disrupt the balance of sex hormones, growth hormones, prolactin, etc., can lead to the development of male breasts.

However, in clinical practice, most patients do not have a found cause, so the etiology is divided into two categories: primary, which means there are no abnormalities in reproductive organ development or other organic changes, and hormone levels are normal with no obvious causes found clinically; and secondary, which refers to cases where a clear cause is evident in clinical practice.