[A case of occult breast carcinoma with irradiation therapy and axillary lymph node dissection]

A 78-year-old woman was seen at the hospital for a swollen left axillary node. There was an elastic hard mass measuring 0.7 cm in diameter in the left axilla, but no breast mass was palpable in the bilateral breasts. Mammography did not reveal any tumor and calcification, and there was no abnormalities on breast ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). Aspiration biopsy cytology of the left axillary node revealed adenocarcinoma. Systemic examination failed to reveal primary lesion. Thus, to make the diagnosis, we enucleated the axillary nodule. Immunohistochemical staining for the excisional specimen revealed an estrogen receptor, progesterone receptor and gross cystic disease fluid protein-15 (GCDFP-15) was strongly positive, so we diagnosed it as an occult breast carcinoma. After obtaining her informed consent, the patient underwent left axillary lymph node dissection and irradiation therapy of the left breast. The patient has been disease-free under adjuvant chemoendocrine therapy. We treated the occult breast carcinoma with radiation therapy of the breast and axillary lymph node dissection, and provided a review of the literature.