What is the appearance of gynecomastia on ultrasound and mammogram?

Gynecomastia Appearance on Ultrasound and Mammogram

Gynecomastia typically appears on ultrasound as a hypoechoic, triangular or flame-shaped retroareolar mass in early stages, while on mammography it presents as a retroareolar density with three distinct patterns: nodular, dendritic, or diffuse, corresponding to different stages and causes of the condition. 1

Ultrasound Findings of Gynecomastia

• Early, focal gynecomastia appears sonographically as a triangular or flame-shaped, hypoechoic mass in the retroareolar area 2, 3
• As gynecomastia becomes more diffuse and chronic, it results in a hyperechoic increase in the glandular parenchyma 2
• Typical sonographic features include:
  • Retroareolar location (100% of cases) 3
  • Hypoechoic appearance (78% of cases) 3
  • Avascular on Doppler imaging (73% of cases) 3
  • Orientation parallel to the chest wall (82% of cases) 3
  • No posterior enhancement or shadowing (64% of cases) 3
• When no discrete mass is present (67% of cases), increased anteroposterior depth at the nipple (>1 cm) is seen in 97% of cases 3

Mammographic Findings of Gynecomastia

• Gynecomastia is visualized on mammography as a subareolar opacity 1
• Three distinct mammographic patterns are recognized, each corresponding to different stages or causes:
  • Nodular pattern: Corresponds to florid gynecomastia of early onset 1
  • Dendritic pattern: Corresponds to fibrous persistent gynecomastia 1
  • Diffuse pattern: Corresponds to gynecomastia due to exogenous estrogen administration 1

Diagnostic Considerations

• Most men with breast symptoms can be diagnosed based on clinical findings without imaging 4
• For men with indeterminate breast masses:
  • Men younger than 25: Ultrasound is the initial recommended imaging study 4
  • Men 25 and older: Mammography or digital breast tomosynthesis is recommended 4
• It is essential to differentiate true gynecomastia from pseudogynecomastia (fatty tissue deposition rather than glandular tissue enlargement), especially in patients with elevated BMI 4, 5
• Breast cancer in males is rare (accounting for <1% of all breast cancers) but should be ruled out, especially in older men (median age 63 years) 4

Imaging Findings Suggestive of Malignancy vs. Gynecomastia

• Suspicious features that may indicate malignancy rather than gynecomastia include:
  • Eccentric location (not directly behind the nipple) 1
  • Irregular margins 1
  • Posterior acoustic shadowing 1
  • Microcalcifications 1
  • Skin thickening or retraction 1
• Figure 2 in the Mayo Clinic Proceedings demonstrates diagnostic mammograms showing a round high-density retroareolar mass in a transgender woman, with ultrasound showing an irregular hypoechoic mass with blood flow - features suspicious for cancer that were confirmed as invasive ductal carcinoma 6

Common Pitfalls in Imaging Evaluation

• Unnecessary imaging in clear cases of gynecomastia can lead to additional unnecessary benign biopsies 4
• Failing to distinguish between true gynecomastia and pseudogynecomastia, especially in obese patients 5
• Not recognizing the various sonographic patterns of gynecomastia, which could lead to unnecessary biopsy based on sonographic findings 3
• Overlooking potential underlying causes of gynecomastia, such as medications, hormonal disorders, or systemic diseases 5

Special Considerations

• Gynecomastia is bilateral in approximately 50% of patients 4
• In patients with BRCA2 mutations and Klinefelter syndrome, there is a higher risk of male breast cancer, warranting careful imaging evaluation 5
• Imaging findings should be classified according to the BI-RADS (Breast Imaging Reporting and Data System) based on their malignant potential 1