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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 26–15)

    • 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, especially efavirenz or didanosine; breast enlargement resolves spontaneously in 73% within 9 months

Table 26–15.Causes of gynecomastia.


  • Incidence is increasing in all age groups

  • Pubertal gynecomastia develops in 60% of boys, more commonly in teenagers who are 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

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 assessment of masculinization

    • Examination of the testes for size and masses

    • Examination of the penis for hypospadias

Differential Diagnosis

  • Male breast cancer

  • Fatty breast ...

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