Solid neuroendocrine carcinomas of the breast: metastases or primary tumors?

Neuroendocrine breast carcinomas are rare but may represent either metastatic or primary lesions. So far, clinical and preoperative histopathological examinations do not distinguish properly between a primary or metastatic breast tumor. Due to any possible consequences following an appropriate treatment, markers which may be helpful for such a distinguishment are needed. We addressed this study in order to evaluate the immunohistochemical expression of GCDFP-15 and mammaglobin in a subset of pure neuroendocrine breast carcinomas (n = 9) and compared the expression profile with a cohort of non-mammary neuroendocrine tumors (n = 99). We observed in our study that solid neuroendocrine breast carcinomas are characterized by the expression of estrogen and progesterone receptors as well as GCDFP-15 and/or mammaglobin. GCDFP-15 was expressed in 6 out of 9 cases, mammaglobin was positive in 4 out of 9 tumors. In contrast, neuroendocrine tumors of the non-mammary cohort expressed neither GCDFP-15 nor mammaglobin. We conclude that mammaglobin and GCDFP-15 as markers of epithelial breast origin may work as a new and reliable diagnostic tool to distinguish primary endocrine tumors of the breast from a metastatic neuroendocrine disease. This is of utmost importance, especially for surgical management

Breast metastasis as the first clinical manifestation of ileal neuroendocrine tumor. A challenging diagnosis with relevant clinical implications

leal neuroendocrine tumors are slow-growing grade 1 or, more rarely, grade 2 neuroendocrine tumors which, however, are frequently metastatic to regional lymph nodes and the liver. A few cases of ileal neuroendocrine tumors that are metastatic to the breast have also been reported in the medical literature. The knowledge of this uncommon clinical presentation is of great importance because it needs to be differentiated from primary breast carcinomas with neuroendocrine features, which represent completely different entities with a different therapeutic approach. The diagnosis of a breast metastasis from an ileal neuroendocrine tumor and its distinction from a well-differentiated primary neuroendocrine tumor of the breast is a challenging task for clinicians and pathologists. This workup is particularly difficult when the breast lesion is the first sign of malignancy. In the present paper, we describe the clinicopathological features of an ileal neuroendocrine tumor first presenting with a breast metastasis in a 50-year-old woman and we discuss the key diagnostic features for the differential diagnosis with primary well-differentiated neuroendocrine tumor of the breast. Moreover, we have reviewed the medical literature to give the reader a comprehensive overview on this topi