[A Case of Axillary Nodal Metastasis of Adenocarcinoma of an Unknown Primary Site Effectively Treated with Anti-HER2plus AC plus Paclitaxel Therapy].

A 68-year-old woman who presented with a left axillary mass was admitted. A computed tomography scan showed swelling ofthe left axillary and supraclavicular lymph nodes, but magnetic resonance imaging(MRI)and fluorodeoxyglucose positron emission tomography(FDG-PET)did not reveal these primary sites. Histological findings of the axillary mass revealed a HER2-positive adenocarcinoma. We diagnosed the patient with axillary nodal metastasis ofadenocarcinoma ofan unknown primary site and treated her with neoadjuvant chemotherapy including paclitaxel and trastuzumab followed by doxorubicin and cyclophosphamide. The lesions almost disappeared after 3 courses of chemotherapy and she showed a pathologically complete response(CR)after surgery. The patient has been recurrence-free since the operation owing to treatment with adjuvant trastuzumab.