📊 Definition & Physiologic Gynecomastia
• Benign enlargement of male breast tissue due to increased estrogen/androgen ratio
• Physiologic pubertal gynecomastia: occurs in up to 60% of boys age 10-16, usually bilateral, breast tissue <4 cm, resolves spontaneously within 2 years
• Physiologic neonatal gynecomastia: from maternal estrogen, resolves weeks
🩺 Pathologic Causes – Red Flags
• Onset before puberty or after age 17
• Macrogynecomastia (>4-6 cm) or persistent >2 years
• Unilateral, hard, fixed, or asymmetric masses
• Associated with hypogonadism (small testes), cryptorchidism, gynecomastia + small testes → Klinefelter syndrome
• Galactorrhea → hyperprolactinemia
⚠️ Common Pathologic Etiologies
• Klinefelter syndrome (47,XXY): tall stature, small firm testes, gynecomastia, infertility, learning disabilities, hypergonadotropic hypogonadism
• Hypogonadism (any cause): androgen deficiency → increased estrogen/androgen ratio
• Testicular tumors: Leydig cell tumor (estrogen-secreting), Sertoli cell tumor (Peutz-Jeghers syndrome)
• Liver disease: decreased estrogen metabolism, increased SHBG
• Hyperthyroidism: increased aromatization, increased sex hormone-binding globulin
• Drugs: estrogens, antiandrogens, spironolactone, cimetidine, ketoconazole, marijuana, anabolic steroids, HAART
📋 Evaluation
• History: medications, illicit drugs, family history, Klinefelter symptoms
• Physical: testicular size (small in Klinefelter, mass in tumor), gynecomastia characteristics
• Labs: LH, FSH, testosterone, estradiol, prolactin, hCG, DHEAS, LFTs, TSH, karyotype if small testes or suspicion of Klinefelter
📌 Decision strategy: Physiologic pubertal gynecomastia is most common. Red flags: prepubertal onset, macrogynecomastia, persistent >2 years, small testes, unilateral firm mass → evaluate for Klinefelter, tumor, hypogonadism.