A male teenager with breast tissue is normal or gynecomastia?

Whether or not norm-: -al doesn't really matter as much as the psychological effect: no teenage or any age male wants to have breasts. Sometimes, the problem is transient and therefore does not indicate treatment and it may also simply be fat if the individual is over wt. If practical, in the remaining cases, most males would benefit from treatment. The best treatment in my opinion, is slim lipo.

Teen Gynecomastia: Teenagers often have excess breast tissue also call gynecomastia. It is best to wait until after puberty as it often self corrects.

Define "normal": Gynecomastia comes from the greek meaning "gyne" meaning woman and  "mastos"  meaning breasts.  it refers to abnormal development of large mammary glands in males. Although there may be many “causes”, most cases are idiopathic (no specific cause). The use of certain medications, drugs, organ dysfunction (kidney or liver), hormonal imbalances etc. May also be causative.