Primary Neuroendocrine Neoplasms of the Breast: Case Series and Literature Review

Abstract

Primary neuroendocrine carcinoma of the breast (NECB) as defined by the World Health Organization (WHO) in 2012 is a rare, but possibly under-diagnosed entity. It is heterogeneous as it entails a wide spectrum of diseases comprising both well-differentiated neuroendocrine tumors of the breast as well as highly aggressive small cell carcinomas. Retrospective screening of hospital charts of 612 patients (2008–2019) from our specialized outpatient unit for neuroendocrine neoplasia revealed five patients diagnosed with NECB. Given the low prevalence of these malignancies, correct diagnosis remains a challenge that requires an interdisciplinary approach. Specifically, NECB may be misclassified as carcinoma of the breast with neuroendocrine differentiation, carcinomas of the breast of no special type/invasive ductal carcinoma, or a metastasis to the breast. Therefore, this study presents multifaceted characteristics as well as the clinical course of these patients and discusses the five cases from our institution in the context of available literature.

Primary Neuroendocrine Neoplasms of the Breast: Still Open Issues

“…Males are rarely affected by BNEN ( 9 , 15 – 17 ). However, despite the overall low incidence, there are proportionally more males with BNEN than with other mammary cancers ( 9 , 17 ). The distribution of ethnicity for BNEN seems to be similar to other mammary cancers ( 9 ).…”

“…Because of all these issues, the discussion of each individual case in an interdisciplinary group of NEN experts is worthwhile in order to provide a tailored treatment for each individual patient ( 17 ).…”

“…Most patients with BNEN are postmenopausal women between their fifth and seventh decade of life (mostly aged >60 years), while the incidence in younger premenopausal women is still lower (5,9,(14)(15)(16)(17). Males are rarely affected by BNEN (9,(15)(16)(17).…”

“…Most patients with BNEN are postmenopausal women between their fifth and seventh decade of life (mostly aged >60 years), while the incidence in younger premenopausal women is still lower (5,9,(14)(15)(16)(17). Males are rarely affected by BNEN (9,(15)(16)(17). However, despite the overall low incidence, there are proportionally more males with BNEN than with other mammary cancers (9,17).…”

“…Less frequently clinical presentations are isolated bloody nipple discharge, isolated skin retraction, anorexia, ulcerated breast masses, carcinomatous mastitis, and Paget like mass (28). In addition, a malignant lesion revealed by routine mammography, performed for family history of breast cancer, has been reported (17). Although extremely rare, a peculiarity of BNEN can be the occurrence of clinical manifestations from ectopic hormonal secretion.…”