What is the appropriate workup for a unilateral breast mass in a male?

Workup for Unilateral Breast Mass in Males

The appropriate workup for a unilateral breast mass in a male should begin with diagnostic mammography or digital breast tomosynthesis (DBT) as the initial imaging study, followed by ultrasound if the mammogram is indeterminate or suspicious. 1

Initial Evaluation

Clinical Assessment

• Evaluate for concerning features:

  • Painless mass (more concerning for malignancy) 2
  • Nipple discharge or retraction 1
  • Axillary adenopathy 1
  • Personal history of cancer (present in 18% of male breast cancer cases) 2
  • Family history of breast cancer (present in 36% of male breast cancer cases) 2

• Assess for potential causes of gynecomastia:

  • Medications (particularly spironolactone, antiandrogens, 5-alpha reductase inhibitors) 3
  • Liver disease, renal insufficiency, obesity 3
  • Hormonal imbalances 3

Imaging Algorithm

1. First-line imaging: Diagnostic mammography or DBT

   • Highly sensitive (92-100%) and specific (90-96%) for distinguishing benign from malignant disease 1
   • Negative predictive value of 99-100% 1
   • Bilateral mammogram is routinely performed to assess symmetry and detect contralateral abnormalities 1

2. Second-line imaging: Ultrasound

   • Indicated when mammogram is indeterminate or suspicious 1
   • Assists in lesion characterization and guides biopsy 1
   • May be less sensitive than mammography (88.9% vs 95%) but similarly specific (95.3%) 1
   • Particularly useful for distinguishing solid from cystic masses 1

3. MRI is generally not indicated for evaluation of male breast masses 1

Tissue Sampling

• Core needle biopsy is recommended for:
  • Suspicious or indeterminate findings on imaging 4
  • Masses that cannot be confidently classified as benign 1
  • Core biopsy is safe and effective for diagnosing unilateral male breast swelling 4

Interpretation of Findings

Mammographic Findings

• Benign findings (gynecomastia):

  • Nodular pattern (34%)
  • Dendritic pattern (35%)
  • Diffuse glandular pattern (31%) 5

• Suspicious findings:

  • Irregular mass
  • Focal asymmetry
  • Microcalcifications (though less common in men) 1
  • Note: Even circumscribed masses should be viewed with suspicion in male patients 1

Ultrasonographic Findings

• Malignant features:
  • Hypoechoic solid masses with irregular borders
  • Irregular contours (present in 80% of male breast cancers) 5
  • Complex cystic and solid masses 1

Important Considerations

• Male breast cancer is uncommon (only 3% of unilateral breast masses in men) but must be excluded 6
• Gynecomastia is the most common cause (83-93%) of unilateral breast masses in men 6, 4
• Men with breast cancer typically present later than those with gynecomastia (median 33 vs 3.4 months) 2
• Physical examination has been documented to be as effective as mammography in distinguishing benign from malignant lesions, but both should be used when there is uncertainty 7
• Absence of pain does not reliably distinguish between benign and malignant conditions 6

Pitfalls to Avoid

• Do not assume a unilateral mass is benign in older men, even with a history of medications known to cause gynecomastia 2
• Do not miss breast cancer obscured by gynecomastia (can occur partially or totally) 5
• Do not dismiss relatively benign imaging findings (such as circumscribed masses) as these should still be considered suspicious in male patients 1
• Do not rely solely on clinical features to distinguish gynecomastia from cancer; imaging is essential 5