medskl.com is a free, global medical education site (FOAMEd) covering the fundamentals of clinical medicine with animations, lectures and concise summaries. medskl.com is working with over 170 award-winning medical school professors to provide content in 200+ clinical presentations. Endocrinology – Gynecomastia: What You Need to Know Whiteboard Animation Transcript with Adam Millar, MD, MScCH https://medskl.com/Module/Index/gynecomastia Gynecomastia is benign enlargement of glandular breast tissue in the male. It’s a common condition, with a reported prevalence of 36% in men between the ages of 17-58. Even higher prevalence rates have been noted in newborns, teenagers and older men due to normal physiologic changes. True gynecomastia is due to the effect of an imbalance of androgenic and estrogenic hormones on glandular breast tissue. An important point is that one doesn’t need to have frankly low testosterone levels or high estradiol levels to develop gynecomastia. Patients with acute gynecomastia will often note unilateral or bilateral breast enlargement with tenderness on palpation. Over time, patients may report decreased enlargement and tenderness – this suggests that the affected tissue may have entered the chronic or fibrotic stage. Although male breast cancer is rare, one must first exclude this condition before proceeding with further investigations into gynecomastia. Physical findings that indicate a potentially malignant lesion include unilateral breast involvement, presence of a hard, fixed mass that is located peripherally to the areola rather than circumferentially, accompanying skin rashes, nipple discharge and axillary lymphadenopathy. In cases where carcinoma is a concern, mammography can help distinguish malignant lesions from benign ones. After exclusion of carcinoma, the next step is differentiating true gynecomastia from pseudogynecomastia (or lipomastia, which is excess fat tissue in the breast). The texture of the mass on exam can help in distinguishing these conditions Initial lab investigations to determine etiology include total testosterone, lutenizing hormone, estradiol, and prolactin. One may also add hCG and bioavailable testosterone. Thyroid, renal, and liver function tests are also important initially. An accurate medication and supplement history is essential, as many of these substances are known to cause gynecomastia. The majority of cases, however, are idiopathic. Management involves treating any underlying condition found on lab testing, or removing offending medications. In other cases, estrogen blocking medications (such as tamoxifen) or surgical intervention may be required for more permanent effect.