Ectopic Breast Cancer Arising within an Axillary Lymph Node.

Area of Science:

• Oncology
• Surgical Pathology
• Radiology

Background:

• Ectopic breast tissue can occur along the embryonic milk lines, including the axilla.
• Malignancies arising in ectopic breast tissue are rare, posing diagnostic challenges.
• Axillary lymph node involvement is common in breast cancer but primary ectopic breast cancer in a lymph node is exceptionally uncommon.

Observation:

• A 65-year-old woman presented with diagnosed breast cancer and axillary lymph node metastasis.
• Post-surgical pathology revealed invasive ductal carcinoma within an axillary lymph node, originating from ectopic mammary tissue.

Findings:

• The malignancy was identified as invasive ductal carcinoma within ectopic breast tissue in an axillary lymph node.
• Distinguishing this ectopic breast cancer from metastatic disease presented diagnostic challenges.

Implications:

• This case highlights the importance of considering ectopic breast tissue in differential diagnoses for axillary masses.
• Accurate pathological identification is crucial for appropriate treatment of rare ectopic breast cancers.