Gynecomastia & Anabolic Steroid Misuse
Separating benign breast growth from tumors, drugs and hidden androgen use
Overview and mechanism
Definition. Gynecomastia is benign proliferation of glandular (ductal and stromal) male breast tissue. Estrogen stimulates it and androgens restrain it, so it follows anything that raises estrogen action relative to androgen action: more estradiol (estrogen-secreting tumors, hCG-driven Leydig-cell aromatase, aromatization in fat), less testosterone (hypogonadism), androgen-receptor blockade, or a higher SHBG, which binds testosterone more tightly than estradiol and lowers the free testosterone:estradiol ratio.
Natural history. Recent tissue is proliferative and often tender. After about 12 months it becomes fibrotic and seldom regresses spontaneously or with drugs, so duration decides between medical therapy and surgery.
Examination: true, pseudo, or cancer?
Technique. With the patient supine and his hands behind his head, bring thumb and forefinger together from opposite edges of the breast toward the nipple. True gynecomastia is a rubbery-to-firm disk concentric with the areola that keeps the fingers apart; it is usually bilateral, often asymmetric, and tender when recent. In the pseudogynecomastia of obesity the fingers meet without a disk, and no hormonal evaluation is needed. Obese men can also have true gynecomastia (adipose aromatase); ultrasound or mammography settles an unclear examination.
Male breast cancer. Carcinoma features (table) call for diagnostic mammography, often with ultrasound, and core-needle biopsy. BRCA2 mutation and Klinefelter syndrome carry the highest risk; about 90% of male breast cancers are hormone receptor–positive.
| Feature | True gynecomastia | Pseudogynecomastia | Male breast cancer |
|---|---|---|---|
| Tissue | Rubbery-to-firm glandular disk | Soft fat, no disk | Hard mass |
| Position | Concentric beneath the areola | Diffuse | Eccentric to the nipple |
| Laterality | Usually bilateral | Bilateral | Usually unilateral |
| Skin and nipple | Normal; tissue mobile | Normal | Fixation, dimpling, retraction, bloody discharge, axillary nodes |
| Pain | Common when recent | Absent | Usually painless |
| Next step | History, exam ± hormone testing | Reassurance | Mammography and core biopsy |
Typical bilateral, centrally placed gynecomastia does not need mammography and is not a precancerous lesion.
Causes
Physiologic peaks. Newborns: maternal estrogen crossing the placenta produces breast buds that fade within weeks. Mid-puberty (about ages 13–14): estradiol rises ahead of testosterone, and most cases regress within 6 months to 2 years, so a boy with normal testes and examination is reassured and re-examined in 3–6 months; prepubertal onset, abnormal testes, very large tissue, or persistence beyond 2 years deserves evaluation. Older men: falling testosterone, more adipose aromatase, rising SHBG, and polypharmacy.
Drugs cause roughly 10–25% of cases and are the most correctable cause:
- spironolactone (androgen-receptor blockade, reduced testosterone synthesis): switch to eplerenone in heart failure; amiloride is the usual substitute for cirrhotic ascites
- cimetidine (antiandrogenic): switch to famotidine or a PPI
- ketoconazole (inhibits testosterone synthesis)
- prostate cancer therapy: bicalutamide, flutamide, enzalutamide, GnRH agonists such as leuprolide; 5α-reductase inhibitors (finasteride, dutasteride)
- digoxin, marijuana, alcohol, opioids, efavirenz, prolactin-raising antipsychotics
- hormones: estrogens, hCG, testosterone and anabolic steroids (aromatized to estradiol)
Systemic disease. Cirrhosis: poor hepatic clearance of androstenedione increases its peripheral aromatization, SHBG rises, alcohol injures Leydig cells, and spironolactone is often prescribed. CKD and dialysis: uremic Leydig-cell failure with low testosterone and high LH. Hyperthyroidism: higher SHBG and aromatase activity.
Hypogonadism. Klinefelter syndrome (47,XXY) is the classic primary cause: tall stature, small firm testes, azoospermia, low testosterone with high LH and FSH, and a greatly increased breast cancer risk. A karyotype confirms it.
Tumors. hCG acts on Leydig-cell LH receptors and stimulates aromatase, so estradiol rises out of proportion to testosterone while LH is suppressed. Sources are testicular or extragonadal (mediastinal, retroperitoneal) germ cell tumors and, rarely, nontrophoblastic cancers such as lung carcinoma. Leydig and Sertoli cell tumors and feminizing adrenocortical tumors secrete estrogen directly. About a quarter of all cases remain idiopathic.
Evaluation
Who needs testing. Incidental, long-standing, painless gynecomastia with a normal history and examination needs only observation. New, painful, enlarging, or large tissue, or any abnormal finding, needs a targeted evaluation.
- HistoryMedications, supplements, alcohol, marijuana, anabolic steroids
- ExaminationBreasts (exclude cancer), testes (mass, atrophy), liver stigmata, thyroid
- Basic labsLFTs, creatinine, TSH
- HormonesMorning total testosterone, LH, estradiol, hCG; prolactin if testosterone and LH are both low
| Pattern | Likely cause | Next step |
|---|---|---|
| ↑ hCG, LH suppressed | Testicular or extragonadal germ cell tumor | Testicular ultrasound; if normal, CT chest and abdomen |
| ↑ Estradiol, ↓ or normal LH | Leydig or Sertoli cell tumor; feminizing adrenal tumor | Testicular ultrasound; if normal, adrenal CT or MRI |
| ↓ Testosterone, ↑ LH | Primary hypogonadism (Klinefelter, CKD) | Karyotype when Klinefelter is suspected |
| ↓ Testosterone, ↓ or normal LH | Secondary hypogonadism | Prolactin, pituitary MRI |
| Suppressed LH and FSH, high hematocrit | Exogenous androgens | Ask directly; counsel to stop |
Management
Treat the cause. Stop or substitute the offending drug, treat hyperthyroidism, remove a tumor, or replace testosterone in confirmed hypogonadism; recent drug-induced tissue usually regresses within months.
Tamoxifen or surgery. For recent (<12 months) painful gynecomastia, tamoxifen 10–20 mg daily for about 3 months reduces pain and size in most men; raloxifene is an alternative, and aromatase inhibitors such as anastrozole work poorly. Long-standing fibrotic tissue, very large gynecomastia, or failed medical therapy calls for subcutaneous mastectomy, often with liposuction. Men starting bicalutamide monotherapy can receive prophylactic tamoxifen or low-dose breast-bud radiation.
Anabolic steroid misuse
Recognition. Supraphysiologic androgens (testosterone esters, nandrolone, stanozolol, oxandrolone) are used in cycles by bodybuilders and athletes. Suspect them in a muscular young man with acne, gynecomastia, and small testes.
- Reproductive: suppressed GnRH, LH, and FSH cause testicular atrophy, oligospermia or azoospermia, and infertility; aromatization to estradiol causes gynecomastia
- Blood and heart: erythrocytosis with thrombotic risk, very low HDL, high LDL, hypertension, LVH, early MI and stroke
- Skin and mood: acne, male-pattern hair loss, irritability, aggression
- Liver (oral 17α-alkylated agents such as methyltestosterone, oxandrolone, stanozolol): cholestatic jaundice, hepatic adenoma, peliosis hepatis (blood-filled cysts that can rupture), hepatocellular carcinoma
- Women: virilization (deep voice, clitoromegaly, hirsutism) that may be permanent; adolescents: premature epiphyseal closure
Labs. LH and FSH are suppressed. Testosterone is high with testosterone esters but low when only synthetic agents such as nandrolone or stanozolol are used.
After androgens are stopped, the suppressed hypothalamic–pituitary–gonadal axis can take months to years to recover. The resulting hypogonadism (low libido, erectile dysfunction, fatigue, depression) often drives relapse, so management is counseling plus follow-up of gonadal function, hematocrit, and lipids.