Metastatic lymph nodes of occult breast cancer show very low internal echoes.

A 62-year-old woman showed an elevation of carcinoembryonic antigen (CEA) level 15 years after the left breast cancer, i.e., tubule forming type luminal micro invasive cancer, operation. Positron emission tomography/computed tomography (PET/CT) showed avid radio-tracer uptake in her right axillary and supraclavicular lymph nodes. Mammography, ultrasound (US), PET/CT, and magnetic resonance imaging showed no abnormalities in her right breast. US of the enlarged lymph nodes showed very low internal echoes. Pathological study using a core needle biopsy specimen of a right axillary node showed human epidermal growth factor receptor type 2 (HER2) positive atypical cells growing in solid and trabecular fashions. Under the presumed diagnosis of right occult breast cancer, the patient received anti-HER2 agents-containing chemotherapy, leading to marked shrinkage of the enlarged lymph nodes with normalization of the elevated CEA level. To confirm the pathological efficacy, sentinel plus sampling node biopsy was done to the patient. Postoperative pathological study of the resected nodes showed fibrosis and no viable cancer cells. The patient further received radiotherapy both to the right breast and suprarclavicular region followed by adjuvant anti-HER2 agents therapy, and has been well without any recurrences for 39 months. Diagnostic physicians should note that metastatic lymph nodes of occult breast cancer show very low internal echoes.