Other potential causes of male breast enlargement such as mastitis, lipoma, sebaceous cyst, dermoid cyst, hematoma, metastasis, ductal ectasia, fat necrosis, or a hamartoma are typically excluded before making the diagnosis. Imaging
Mammography is the method of choice for radiologic examination of male breast tissue in the diagnosis of gynecomastia when breast cancer is suspected on physical examination. If a mass/lump is felt during a physical exam some features of the lump that would point to malignancy would be painless, non moveable (fixed), irregularly shaped, and skin changes. Mammography is rarely indicated for men since breast cancer is an unlikely diagnosis. If mammography is performed and does not reveal findings suggestive of breast cancer, further imaging is not typically necessary. If a tumor of the adrenal glands or the testes is thought to be responsible for the gynecomastia, ultrasound examination of these structures may be performed. Histology
Early histological features expected to be seen on examination of gynecomastic tissue attained by fine-needle aspiration biopsy include the following: proliferation and lengthening of the ducts, an increase in connective tissue, an increase in inflammation, and swelling surrounding the ducts, and an increase in fibroblasts in the connective tissue. Chronic gynecomastia may show different histological features such as increased connective tissue fibrosis, an increase in the number of ducts, less inflammation than in the acute stage of gynecomastia, increased subareolar fat, and hyalinization of the stroma.
During pregnancy, the placenta converts the androgenic hormones dehydroepiandrosterone (DHEA) and DHEA sulfate to the estrogenic hormones estrone and estradiol, respectively; after these estrogens are produced by the placenta, they are transferred into the babys circulation, thereby leading to temporary gynecomastia in the baby. In some infants, neonatal milk (also known as "witchs milk") can leak from the nipples. The temporary gynecomastia seen in newborn babies usually resolves after two or three weeks. Adolescents
Hormonal imbalance (elevated ratio of estrogen to androgen) during early puberty, either due to decreased androgen production from the adrenals and/or increased conversion of androgens to estrogens, leads to transient gynecomastia in adolescent males. It can occur in up to 65% of adolescents as early as age 10 and peaks at ages 13 and 14. It is self-limited in 75-90% of adolescents and usually resolves spontaneously within 1 to 3 years as pubertal progression increases testosterone levels and cause regression of breast tissue. By age 17, only 10% of adolescent males have persistent gynecomastia. Older adults
Declining testosterone levels and an increase in the level of subcutaneous fatty tissue seen as part of the normal aging process can lead to gynecomastia in older males. Increased fatty tissue, a major site of aromatase activity, leads to increased conversion of androgenic hormones such as testosterone to estrogens. Additionally, levels of sex hormone binding globulin (SHBG) increase with age and bind with less affinity to estrogen than androgens.