Causes and Diagnosis of Left Axillary and Left Breast Lymphadenitis

Primary Diagnostic Considerations

The National Comprehensive Cancer Network recommends that when cancer is identified in axillary lymph nodes, breast cancer is the most common cause of axillary lymphadenopathy, though localized axillary masses are more often related to benign disorders than malignancy 1
Ipsilateral breast cancer is the leading malignant cause when cancer is confirmed in axillary nodes 1
Occult breast cancer can present with isolated axillary masses—in one study, 9 of 17 cancer cases had occult breast cancer, with 5 in the contralateral breast 1
Metastatic adenocarcinoma from breast origin may be present even when initial ultrasound and mammography show no breast abnormality 1

Cellulitis of the breast, arm, or chest (particularly in patients with pre-existing lymphedema) can cause axillary lymphadenopathy 2, 3
Reactive lymphadenopathy from mastitis can cause axillary lymphadenopathy 4
Granulomas can cause axillary lymphadenopathy 4
Breast implant-related benign axillary lymphadenopathy can occur 1

Axillary lymph node dissection for breast cancer has a 30-50% risk of causing secondary lymphedema 5
Radiation therapy to supraclavicular lymph nodes or axilla can cause secondary lymphedema 2, 5, 6
Combined surgery and radiation creates additive risk of secondary lymphedema 5
Secondary lymphedema may develop immediately after treatment or years later (up to 11-30 years post-treatment) 5, 7

A complete clinical evaluation to assess for other sites of adenopathy and potential non-breast etiologies is recommended 1
Assess for signs of systemic disease or lymphoma 1
Evaluate for history of breast cancer treatment, breast implants, or recent infections 1, 8
For patients ≥30 years, ultrasound with mammogram is recommended 1
For patients <30 years, ultrasound alone is recommended 1
Core needle biopsy is recommended for palpable axillary mass that is suspicious or highly suggestive on imaging 1
If cellulitis develops in a patient with lymphedema, treat promptly with antibiotics as it can significantly exacerbate lymphedema 2, 3, 7