What is the evaluation and management approach for axillary lymphadenopathy?

Evaluation and Management of Axillary Lymphadenopathy

Ultrasound of the axilla is the primary imaging modality for evaluating axillary lymphadenopathy, complemented by age-appropriate breast imaging (diagnostic mammography/DBT for patients ≥30 years, ultrasound alone for patients <30 years) to identify potential breast primaries. 1, 2

Initial Clinical Assessment

• Perform a complete clinical evaluation to assess for systemic disease, other sites of adenopathy, and non-breast etiologies of lymphadenopathy 1
• Document vaccination history (vaccine type, date, and injection site) as COVID-19 and other vaccines can cause axillary lymphadenopathy lasting over 100 days 3, 4
• Determine whether the presentation is unilateral or bilateral, as this affects the differential diagnosis 1

Age-Stratified Imaging Approach

Patients <30 Years Old

• Start with axillary ultrasound as the primary imaging modality 1
• Add diagnostic mammography or DBT only if ultrasound reveals suspicious findings requiring further breast parenchymal evaluation 1

Patients 30-39 Years Old

• Perform both axillary ultrasound AND diagnostic mammography or DBT at the initial evaluation 1
• These modalities are complementary and should be done together 1

Patients ≥40 Years Old

• Perform diagnostic mammography or DBT with complementary axillary ultrasound regardless of mammographic findings 1
• This combination evaluates both for occult breast malignancy and characterizes the lymph nodes 1

Ultrasound Interpretation and Next Steps

Benign-Appearing Nodes

• Normal fatty hilum, oval shape, and appropriate size suggest benign reactive lymphadenopathy 1
• Clinical management depends on clinical suspicion; observation may be appropriate for low-risk presentations 1

Suspicious Sonographic Features

• Proceed directly to ultrasound-guided core needle biopsy for nodes with: 1, 2

  • Loss of fatty hilum
  • Rounded shape
  • Length >33 mm (strongly associated with malignancy, 97% specificity) 5
  • Ill-defined or spiculated margins 5
  • Generalized increased density 6

• Core needle biopsy provides high specificity (98-100%) for definitive diagnosis 2

Special Considerations

Bilateral Axillary Lymphadenopathy

• The differential includes reactive lymphadenopathy from infectious/inflammatory processes, lymphoma, leukemia, and metastatic breast cancer 1
• If systemic disease or lymphoma is suspected, CT chest/abdomen/pelvis may be indicated to assess for additional lymphadenopathy and organ involvement 1
• FDG-PET/CT is not recommended as an initial test but may be useful for staging confirmed malignancy 1

Vaccine-Associated Lymphadenopathy

• If lymphadenopathy persists >3 months after COVID-19 vaccination, perform sonographic follow-up after an additional 3 months 3
• Do not delay biopsy or cancer staging for follow-up intervals if breast cancer is confirmed or highly suspected 3
• Biopsy is indicated for nodes that are persistent, progressive, or remain suspicious on follow-up imaging 3

When Breast Cancer is Confirmed

• If core biopsy shows metastatic breast adenocarcinoma but mammography and ultrasound are negative for a breast primary, perform breast MRI which detects occult breast cancer in approximately 70% of cases 1, 2
• Do not delay preoperative staging or treatment planning with prolonged follow-up intervals 3

Management Based on Biopsy Results

Metastatic Breast Cancer

• Complete breast imaging workup with diagnostic mammography/DBT and breast MRI 2
• Follow NCCN Guidelines for Breast Cancer for axillary management 1

Lymphoma or Other Malignancy

• Appropriate staging with CT chest/abdomen/pelvis or PET/CT 2, 7
• Excisional biopsy may be preferred over fine needle aspiration for lymphoma to provide adequate tissue for immunophenotyping 7

Benign Findings

• Common benign causes include reactive changes (most common at 29%), collagen vascular disease, sarcoidosis, and infection 5
• Manage clinically based on underlying etiology 1

Critical Pitfalls to Avoid

• Do not rely on physical examination alone for axillary node assessment, as sensitivity and specificity are limited 2
• Do not delay biopsy of suspicious nodes, as early diagnosis significantly impacts treatment planning and prognosis 2
• Do not assume vaccine-related lymphadenopathy without proper investigation, especially in high-risk patients or when nodes persist beyond expected timeframes 3, 4
• Do not use FDG-PET/CT or MRI as initial imaging tests for axillary lymphadenopathy evaluation 1
• In patients with breast implants, be aware that silicone adenitis can cause a "snowstorm" appearance on ultrasound and mimic malignancy 1