Breast metastasis from small cell neuroendocrine carcinoma of the cervix: a rare case report

Background: Breast metastasis from small cell neuroendocrine carcinoma (SCNEC) of the cervix is an extremely rare condition with a poor prognosis. Metastatic SCNEC to the breast is difficult to differentiate from primary breast carcinoma on the basis of the clinical presentation alone. Case Description: We report the case of a 23-year-old woman who was previously diagnosed with cervical cancer. She had undergone definitive concurrent chemoradiation treatment 1 year earlier and presented at this visit with left breast masses. Breast ultrasonography revealed two microlobulated hypoechoic masses with vascularity. Computed tomography revealed enlarged left supraclavicular lymph nodes, and multiple lung, skin, and peritoneal metastases. Core needle biopsies of the left breast masses indicated small cell tumors. Immunohistochemical staining revealed tumor cells diffusely positive for pancytokeratin (AE1/AE3), synaptophysin, chromogranin, paired-box gene 8, and p16. These were the same histological results as those for the previous cervical mass. Metastatic SCNEC from the cervix associated with human papillomavirus infection was diagnosed. We planned to initiate systemic chemotherapy; however, the patient's condition worsened rapidly, and chemotherapy was omitted. The patient died 2 months after the initiation of supportive care. Conclusions: This case adds to the knowledge of an extremely rare presentation of breast metastases from an extramammary malignancy, cervical SCNEC. It is important to differentiate between primary breast cancer metastasis and metastasis to the breast from other cancers because of the different therapeutic options.