Metachronous bilateral breast metastases of a lung neuroendocrine tumor: A case report.

Breast metastases of primary lung neuroendocrine tumors are rarely reported. The current report presents the case of a 41-year old female with no history of smoking who initially underwent surgery for a breast fibroadenoma, during which a neuroendocrine tumor of the right lung was detected via chest X-ray. The patient underwent surgery for the tumor and developed right breast nodules after adjuvant chemotherapy. Histological and immunohistochemical examinations of biopsies from these nodules indicated breast metastasis of the primary lung neuroendocrine tumor. The patient underwent mastectomy of the right breast but subsequently developed metastases in the left breast, for which local radiotherapy was administered. The observed metachronous bilateral breast metastases indicated that the contralateral breast should be considered during an investigation of metastasis.