What is the management plan for an identified intramammary (within the breast) lymph gland?

Management of Intramammary Lymph Nodes in Breast Cancer

When an intramammary lymph node (IMLN) is identified in a breast cancer patient, sentinel lymph node biopsy should be performed to accurately stage the axilla, and if the sentinel node is negative, a complete axillary lymph node dissection can be avoided even with a positive IMLN. 1

Understanding Intramammary Lymph Nodes

• Intramammary lymph nodes are present in up to 47% of breasts and may be involved in metastatic disease in up to 9.8% of operable breast cancer cases 2
• IMLNs can be located in any quadrant of the breast mound and are increasingly recognized with wider acceptance of high-quality screening mammography and ultrasound assessment 2, 3
• These nodes are true lymph nodes within breast-specific tissue that includes ductal and glandular structures 3

Diagnostic Evaluation

• IMLNs can be identified by imaging methods including mammography, ultrasound, and MRI 3
• Fine-needle aspiration (FNA) is commonly used to sample these nodes, though core or excisional biopsy may also be performed 3
• Contrast-enhanced MRI may show strong and rapid uptake in IMLNs with lymphoid hyperplasia, which can mimic malignant lesions 4

Prognostic Significance

• Positive IMLNs are associated with more aggressive disease characteristics 5:
  • Higher rates of invasive versus non-invasive cancers (95% invasive with positive IMLNs vs. 77% with negative IMLNs) 5
  • Increased lymphovascular invasion (55% vs. 11%) 5
  • Higher rate of axillary lymph node involvement (72% vs. 18%) 5

Management Algorithm

For IMLNs Identified on Imaging:

1. Tissue sampling is essential to determine if the IMLN contains metastatic disease 3, 5

   • FNA, core biopsy, or excisional biopsy may be used 3

2. If IMLN is negative for metastasis:

   • Continue with standard breast cancer management based on primary tumor characteristics 5
   • No additional axillary surgery is required beyond what would be indicated for the primary tumor 5

3. If IMLN is positive for metastasis:

   • Perform sentinel lymph node biopsy (SLNB) of the axilla 1, 5
   • If axillary SLN is negative:
     • Evidence shows that a complete axillary lymph node dissection (CALND) can be avoided 1
     • In a study of 23 patients with positive IMLN but negative axillary SLN who underwent CALND, all had negative CALND results 1
   • If axillary SLN is positive:
     • Complete axillary lymph node dissection should be performed 5
     • Consider regional nodal irradiation based on the extent of nodal involvement 6

4. Staging implications:

   • Positive IMLNs should be counted as positive lymph nodes in the N staging 6
   • This may affect the overall stage and subsequent treatment decisions 5

Treatment Considerations

• Patients with positive IMLNs are more likely to require mastectomy (75% vs. 54% with negative IMLNs) 5
• Positive IMLNs may influence the choice of adjuvant therapy due to their association with more aggressive disease 5
• For patients with positive IMLNs and positive axillary nodes, consider regional nodal irradiation including the supraclavicular region if 4 or more nodes are positive 7

Important Caveats

• The presence of metastatic disease in an IMLN is associated with a high rate of axillary nodal involvement (72%) 5
• Preoperative lymphoscintigraphy may help identify these extra-axillary metastases 5
• IMLNs affected by benign processes can present findings similar to malignant lesions on imaging, making tissue sampling crucial for accurate diagnosis 4
• IMLN metastases alter the prognosis and management of breast cancer patients, which becomes increasingly important as sentinel node biopsy is more widely utilized 2