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Gynecomastia Gynecomastia refers to enlargement of the male breast. It is caused by excess estrogen action and is usually the result of an increased estrogen/androgen ratio. True gynecomastia is associated with glandular breast tissue that is 4 cm in diameter and often tender. Glandular tissue enlargement should be distinguished from excess adipose tissue: glandular tissue is firmer and contains fibrous-like cords. Gynecomastia occurs as a normal physiologic phenomenon in the newborn (due to transplacental transfer of maternal and placental estrogens), during puberty (high estrogen to androgen ratio in early stages of puberty), and with aging (increased fat tissue and. | r m Ấ 7- r Nữ Hóa Tuyên Vú Gynecomastia Gynecomastia refers to enlargement of the male breast. It is caused by excess estrogen action and is usually the result of an increased estrogen androgen ratio. True gynecomastia is associated with glandular breast tissue that is 4 cm in diameter and often tender. Glandular tissue enlargement should be distinguished from excess adipose tissue glandular tissue is firmer and contains fibrous-like cords. Gynecomastia occurs as a normal physiologic phenomenon in the newborn due to transplacental transfer of maternal and placental estrogens during puberty high estrogen to androgen ratio in early stages of puberty and with aging increased fat tissue and increased aromatase activity but it can also result from pathologic conditions associated with androgen deficiency or estrogen excess. The prevalence of gynecomastia increases with age and body mass index BMI likely because of increased aromatase activity in adipose tissue. Medications that alter androgen metabolism or action may also cause gynecomastia. The relative risk of breast cancer is increased in men with gynecomastia although the absolute risk is relatively small. Pathologic Gynecomastia Any cause of androgen deficiency can lead to gynecomastia reflecting an increased estrogen androgen ratio as estrogen synthesis still occurs by aromatization of residual adrenal and gonadal androgens. Gynecomastia is a characteristic feature of Klinefelter syndrome Chap. 343 . Androgen insensitivity disorders also cause gynecomastia. Excess estrogen production may be caused by tumors including Sertoli cell tumors in isolation or in association with Peutz-Jegher syndrome or Carney complex. Tumors that produce hCG including some testicular tumors stimulate Leydig cell estrogen synthesis. Increased conversion of androgens to estrogens can be a result of increased availability of substrate androstenedione for extraglandular estrogen formation CAH hyperthyroidism and most feminizing adrenal .