Primary Neuroendocrine Tumors of the Breast: A Case Report and Literature Review

Primary neuroendocrine tumors (NETs) of the breast are a very rare type of tumor, originating from cells that make up the neuroendocrine system and produce peptides and amines. This type of tumor represents a very rare subtype of breast carcinoma, occurring mainly in postmenopausal women. Breast NETs are graded as well-differentiated G1, moderately differentiated G2, and poorly differentiated G3 (small or large cell neuroendocrine carcinoma), according to the Nottingham system. Neuroendocrine carcinomas usually affect the gastrointestinal and the pulmonary system. We present a rare case of an 88-year-old woman who presented with a right breast mass, which was identified 1.5 months prior. The patient reported mild pain and localized tenderness throughout the day. She underwent a right breast lumpectomy for a palpable mass located in the upper inner quadrant. The pathological identification revealed histologic sections of neoplastic mammary gland tissue exhibiting neuroendocrine immunomorphological features, consistent with a well-differentiated grade. This case highlights the rarity of primary neuroendocrine tumors of the breast and the importance of an early diagnosis. Further studies are needed in order to better understand the biological behavior of the tumor and discover optimal therapies to maximize patient outcomes.