Documentation and Assessment of the Axillary Region
Ultrasound of the axilla is the most appropriate initial imaging modality for documenting and evaluating axillary masses or lymphadenopathy. 1
Approach to Axillary Assessment
Initial Evaluation
- Axillary ultrasound (US) should be the first-line imaging modality for evaluating palpable axillary masses, as it can differentiate between solid and cystic lesions and characterize lymph nodes 1
- Diagnostic mammography and/or digital breast tomosynthesis (DBT) should complement axillary US to evaluate for underlying breast lesions, especially when axillary lymphadenopathy is present 1
Documentation of Axillary Findings
- When documenting axillary findings, specify the anatomic location within the axilla (e.g., level I, II, or III lymph nodes) 1
- Note the size, shape, cortical thickness, and hilum appearance of lymph nodes 2
- Document the relationship of suspicious nodes to surrounding structures including vessels, nerves, and chest wall 1, 3
Imaging Protocol for Axillary Assessment
Ultrasound Technique
- Position the patient supine with arm hyperabducted 4
- Use a high-frequency linear transducer (7.5 MHz or higher) 4, 2
- Scan in both transverse and sagittal planes, with special attention to the axillary vessels 4
- Use the pectoral muscles as guiding structures to locate important lymph node groups 4, 3
Suspicious Findings on Ultrasound
- Cortical thickening >3mm 2
- Loss of fatty hilum 2
- Round rather than oval shape 2
- Irregular margins or extracapsular extension 2
Management of Axillary Findings
Biopsy of Suspicious Nodes
- US-guided core biopsy or fine needle aspiration (FNA) is recommended for suspicious axillary nodes 1
- When performing biopsy, document the location of the biopsied node with a clip if the patient is a candidate for neoadjuvant chemotherapy 1
Surgical Approach to the Axilla
- For patients with breast cancer and clinically negative axilla, sentinel lymph node biopsy (SLNB) is the standard approach 1
- For clinically positive axilla with biopsy-confirmed metastasis, axillary lymph node dissection (ALND) may be indicated 1
- Separate incisions should be used for breast conservation surgery and axillary surgery to avoid unnecessary deformity 1
Special Considerations
- In patients receiving neoadjuvant chemotherapy with initially positive nodes, targeted axillary dissection of the previously biopsied and clipped node in addition to sentinel nodes is recommended 1
- For patients with ductal carcinoma in situ (DCIS) requiring mastectomy, consider sentinel node biopsy at the time of mastectomy since the procedure cannot be performed after mastectomy if invasion is later found 1
Common Pitfalls and Caveats
- Relying solely on clinical examination of the axilla is insufficient; imaging is necessary for accurate assessment 1
- Not all enlarged lymph nodes are malignant; many non-malignant etiologies exist including infection, inflammatory disease, and autoimmune conditions 1, 5
- Frozen section examination of image-guided needle biopsies for non-palpable lesions or microcalcifications should be avoided as it may compromise final diagnosis 1
- Stripping of the axillary vein during surgery should be avoided as it increases the risk of lymphedema 1
- The long thoracic nerve, thoracodorsal nerve, and medial pectoral nerve should be preserved during axillary surgery to prevent functional deficits 1