Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!

For further information, see CMDT Part 26-32: Gynecomastia

Key Features

Essentials of Diagnosis

  • Palpable enlargement of the male breast, often asymmetric or unilateral

  • Fatty gynecomastia is typically nontender

  • Glandular gynecomastia is tender

  • Gynecomastia must be distinguished from carcinoma or mastitis

General Considerations


  • Endocrine (Table 26–14)

    • Hyperprolactinemia

    • Hyperthyroidism

    • Klinefelter syndrome

    • Hypogonadism

  • Systemic disease: chronic liver or kidney disease

  • Neoplasm

    • Testicular

    • Adrenal

    • Lung

    • Liver (rare)

  • Drugs (selected)

    • Alcohol, marijuana

    • Amiodarone

    • Cimetidine, omeprazole

    • Diazepam

    • Digoxin

    • Estrogens, progestins, testosterone

    • Finasteride

    • Flutamide

    • Isoniazid

    • Ketoconazole

    • Opioids

    • Spironolactone

    • Tricyclic antidepressants

  • Pubertal gynecomastia

  • HIV infection treated with antiretroviral therapy (ART), especially efavirenz or didanosine; breast enlargement resolves spontaneously in 73% within 9 months

Table 26–14.Causes of gynecomastia.


  • Incidence appears to be increasing in all age groups

  • About 60% of boys develop pubertal gynecomastia, especially boys taller and heavier than average

  • Particularly common in teenagers who are very tall or overweight

  • About 20% of adult gynecomastia is caused by drug therapy

  • Fatty pseudogynecomastia is common among elderly men, particularly when there is associated weight gain

  • Develops in ~50% of athletes who abuse androgens and anabolic steroids

Clinical Findings

Symptoms and Signs

  • Female-appearing male breast

  • Graded according to severity: I (mild), II (moderate), III (severe)

  • Breast enlargement may be

    • Fatty

      • Usually diffuse

      • Nontender

    • Glandular

      • Asymmetric or unilateral, "lumpy"

      • Glandular enlargement beneath the areola, may be tender

  • Pubertal gynecomastia: tender discoid enlargement of breast tissue beneath the areola, 2–3 cm in diameter

  • The following characteristics are worrisome for malignancy

    • Asymmetry

    • Location not immediately below the areola

    • Unusual firmness

    • Nipple retraction, bleeding, or discharge

  • Testicular examination must be done, may reveal neoplasm

  • Examination must also include

    • An ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.