What happened, in summary

This 48-year-old woman was diagnosed with a 2 cm ductal carcinoma in the retroareolar region of the right breast. She had no prior breast or axillary surgery. Manual examination and ultrasound of the axilla were negative, so her care team recommended lumpectomy with sentinel lymph node biopsy. The day before surgery, lymphoscintigraphy was performed using peritumoral technetium-99m nanocolloid injections. Imaging showed an unusual lymphatic drainage pattern: drainage went not only to the right axillary nodes, but also to the ipsilateral internal mammary chain and the contralateral axillary nodes. Because sentinel node drainage appeared in all 3 territories, the surgical team sampled sentinel nodes from each of them during the lumpectomy procedure. Frozen section and later detailed paraffin-section review did not show metastasis in any of the lymph nodes. Immunohistochemical delayed studies were also negative. Because the nodes were negative, regional lymphadenectomy was not performed. She then received chemotherapy, radiotherapy, and hormone therapy as adjuvant treatment after surgery. No significant complications were observed during the documented treatment course. Two years and 6 months after surgery, she remained free of disease. The case is notable because it shows that sentinel lymph node drainage in breast cancer can occasionally cross expected anatomic boundaries, and sampling all identified drainage sites helped avoid unnecessary regional lymphadenectomy. The sentinel-node findings were clinically useful because they allowed the team to confirm the absence of nodal spread in all mapped drainage areas while avoiding a larger lymph-node dissection. The follow-up result supports a disease-free outcome after combined local and systemic therapy.