Evaluation and Management of Axillary Lumps

Initial Assessment and Imaging

The American College of Radiology recommends beginning with ultrasound of the axilla as the initial imaging modality to differentiate benign from malignant masses and determine if the lesion is solid or cystic 1
Key historical features to elicit include duration of the lump and whether it is increasing in size, which is a red flag for malignancy 2
Associated symptoms such as breast changes, nipple discharge, skin alterations, chest pain, and arm swelling should be assessed 3
A personal history of breast cancer or other malignancies is relevant, as it increases the risk of metastatic disease 3, 5
Family history of breast, ovarian, or other cancers is also important to consider 3
Physical examination must include bilateral breast examination for masses, skin changes, nipple abnormalities, and assessment of both axillae for size, mobility, and characteristics of lymph nodes 1, 3, 6

Ultrasound of the axilla can determine if the mass is solid, cystic, or a lipoma, and assess lymph node architecture and cortical thickness 1
For women ≥40 years with an axillary lump, diagnostic mammography should be performed to evaluate for an occult breast primary 1, 6
Image-guided core needle biopsy is recommended when ultrasound findings are uncertain or suspicious, as it provides superior sensitivity, specificity, and histological grading 1, 4, 6
Indications for biopsy include enlarged lymph nodes with abnormal cortical thickening or loss of fatty hilum, and solid masses that cannot be definitively characterized as benign 1

The differential diagnosis for an axillary lump includes benign etiologies such as reactive lymphadenopathy, lipomas, and accessory breast tissue, as well as malignant etiologies like metastatic breast cancer, lymphoma, and leukemia 1, 3
If imaging shows clearly benign features, return to clinical follow-up only, with no further imaging or biopsy needed 4, 6
If imaging shows suspicious features, proceed directly to image-guided core biopsy, and if malignancy is confirmed, assess hormone receptors and HER2 status 1, 4, 5, 6
If breast cancer is suspected but no primary is identified, consider breast MRI, which detects occult breast cancer in more than two-thirds of patients with axillary metastases 1