A case of multicentric low-grade neuroendocrine breast tumor with an unusual histological pattern.

Neuroendocrine features are detectable in carcinomas of the breast either as scattered cells, that are recognized by their expression of neuroendocrine cell markers. Instead, pure breast carcinomas with neuroendocrine features (NEBC) are very rare and represent <1% of all breast cancer. Usually NEBC may be well or poorly differentiated and more frequent in older woman. These tumors showed variable histological pattern but a common feature is represented by expression of neuroendocrine markers. Here we report a case of a primary multicentric low-grade neuroendocrine carcinoma of the breast presented because of its rarity and for the unusual tubular and cribriform pattern resembling a well-differentiated conventional breast carcinoma. The tumor was treated with left quadrantectomy with concomitant wide excisional biopsy of other two nodules and lymph node sentinel biopsy. No recurrence was observed during 1-year follow-up. Because of its rarity and variability of morphologic features, there exist diagnostic challenges for pathologists to differentiate primary NEBC to some conventional breast carcinomas and to the breast metastasis from neuroendocrine tumor of the lung or gastrointestinal tract. It is important to be able recognize this tumor in order to avoid potential misdiagnosis and improper management of afflicted patients.