A 14-year-old boy presents with gynecomastia (bilateral breast tissue enlargement) for 6 months. There is no galactorrhea, testicular mass, or hepatomegaly. He is Tanner stage 3 for genital development. What is the MOST likely explanation for his gynecomastia?
- A Klinefelter syndrome (47,XXY) — most likely cause in this age group
- B Physiological pubertal gynecomastia due to transient estrogen/androgen imbalance ✓
- C Drug-induced gynecomastia (suspect spironolactone use)
- D Testicular Leydig cell tumor secreting estrogen
Explanation
Physiological pubertal gynecomastia is the most common cause of bilateral gynecomastia in adolescent boys, occurring in up to 50–65% of pubescent males during Tanner stages 2–3 as a result of transient relative excess of estrogen over androgens during early puberty (peripheral aromatization of adrenal androgens to estrogen temporarily exceeds testicular androgen production). It is bilateral, typically <4 cm, non-tender, and self-resolving within 2 years. Klinefelter syndrome should be considered if gynecomastia is severe/persistent with small testes. A testicular mass, liver disease, or drug history must be excluded, but in this clinical context physiological gynecomastia is most likely.
Reference: Ghai Essential Pediatrics, 10th ed.
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