I have swollen lymph nodes under my left axilla for 6 months and now I'm experiencing pain and burning on the side and under my left breast, what could be the cause?

Urgent Evaluation Required for Persistent Axillary Lymphadenopathy with New Breast Symptoms

You need immediate diagnostic imaging with axillary ultrasound and diagnostic mammography or digital breast tomosynthesis (DBT), followed by ultrasound-guided biopsy of any morphologically abnormal lymph nodes to rule out breast cancer or other malignancy. 1, 2

Why This Requires Urgent Workup

The combination of 6-month persistent unilateral axillary lymphadenopathy with new ipsilateral breast pain/burning is concerning for:

• Breast cancer with axillary metastases - the most common malignant cause when cancer is identified in axillary nodes 2
• Occult breast cancer - can present with axillary metastases without a detectable breast mass in less than 1% of cases 2
• Lymphoma - particularly non-Hodgkin's lymphoma, which can present with axillary adenopathy 2
• Other malignancies - metastases from melanoma, lung cancer, or other primary sites 3, 4

The 6-month duration makes benign reactive lymphadenopathy from simple infection much less likely, as these typically resolve within weeks. 2, 3

Recommended Diagnostic Algorithm

Step 1: Initial Imaging (Perform Both)

Diagnostic mammography or DBT of both breasts:

• Can identify a breast cancer that has metastasized to the axilla 1
• May detect silicone in low axillary nodes if you have breast implants 1
• Essential even if no palpable breast mass is present 2

Axillary ultrasound (complementary and mandatory):

• Can identify morphologically abnormal lymph nodes suggesting metastatic disease 1, 2
• Evaluates cortical thickness, uniformity, size, shape, and vascularity patterns 5
• Can diagnose silicone adenitis if implants are present (shows "snowstorm" appearance) 1, 2
• Should be performed regardless of mammography findings 1

Step 2: Tissue Diagnosis

If ultrasound shows morphologically abnormal lymph nodes:

• Ultrasound-guided fine needle aspiration (FNA) or core biopsy is required for definitive diagnosis 1, 5
• Biopsy should be performed on all lymph nodes larger than 1 cm without fatty hilum 6
• Do not rely on imaging characteristics alone to distinguish benign from malignant 6, 7

If breast parenchymal abnormalities are identified:

• Targeted ultrasound and biopsy of suspicious breast findings 1
• Consider breast MRI with and without contrast if mammography and ultrasound are negative but biopsy shows axillary metastatic disease from occult breast primary 1

Step 3: Additional Staging if Malignancy Confirmed

If biopsy confirms malignancy:

• PET/CT should be considered if lymphoma or non-breast malignancy is suspected 5
• CT chest/abdomen/pelvis may be warranted to evaluate for primary malignancy if metastatic disease is suspected 5
• Systemic staging with CT and bone scan if inflammatory breast cancer is diagnosed 1

Critical Pitfalls to Avoid

Do not observe and wait - Pathological axillary lymph nodes characterized by increased density, round/irregular shape, and lack of fatty hilum indicate significant disease requiring investigation 7

Do not assume benign etiology without tissue diagnosis - While autoimmune diseases, infections, and dermatopathic lymphadenopathy can cause axillary adenopathy 2, the 6-month persistence and new breast symptoms mandate exclusion of malignancy first 4, 7

Do not skip breast imaging even with negative clinical breast exam - In one series, 9 of 17 patients with isolated axillary masses and confirmed cancer had occult breast cancer, with 5 in the contralateral breast 2

Do not perform extensive investigations searching for an occult primary before confirming malignancy - Once malignancy is confirmed histologically, limit investigations to searching for treatable malignancies only 4

Special Considerations

If you have breast implants:

• Silicone adenitis from ruptured implants can mimic malignancy and show FDG uptake on PET/CT 2
• Ultrasound showing "snowstorm" appearance in lymph nodes is diagnostic of silicone adenitis 1, 2
• However, benign lymphadenopathy can also occur with intact implants 2

The new breast pain/burning is significant:

• May indicate an underlying breast parenchymal lesion not yet palpable 1
• Could represent inflammatory changes associated with malignancy 1
• Warrants thorough breast parenchymal evaluation even if no mass is palpable 1