# Primary Neuroendocrine Tumor of the Breast: A Rare Case

## TL;DR

A rare case of primary neuroendocrine tumor in a 54-year-old woman's breast is reported, highlighting its unique characteristics and treatment approach.

## Contribution

This case study contributes to the limited understanding of primary neuroendocrine tumors of the breast through detailed clinical and pathological analysis.

## Key findings

- The tumor was positive for estrogen and progesterone receptors but negative for HER2.
- Immunohistochemistry showed positivity for neuroendocrine markers chromogranin A and synaptophysin.
- The patient underwent mastectomy and hormonal therapy, with a low Ki-67 proliferation index indicating a less aggressive tumor.

## Abstract

Primary neuroendocrine tumors (NETs) predominantly affect postmenopausal women. This case study focused on a 54-year-old woman who presented with a painless right breast lump. While the lump exhibited estrogen and progesterone receptor (PR) positivity, it lacked human epidermal growth factor receptor 2 expression. Further evaluation revealed positivity for the neuroendocrine markers chromogranin A (CGA) and synaptophysin (SYN). It also revealed a 3% positive Ki-67 proliferation index. Treatment for neuroendocrine breast cancer (NEBC) mirrors that of standard invasive breast cancer: breast conservation or mastectomy combined with sentinel lymph node biopsy or axillary dissection. The patient underwent a right mastectomy with sentinel lymph node biopsy, followed by hormonal therapy based on her tumor's immunohistochemical profile. Due to the low incidence and limited research on primary NETs, their exact origin remains shrouded in mystery. Accurate diagnosis, specific treatment options, and long-term prognosis remain significant challenges in managing this rare form of breast cancer.