Primary Neuroendocrine Tumor of the Breast: A Case Report and Review of Current Guidelines.

Primary neuroendocrine tumor of the breast is a rare subtype of breast carcinoma that most commonly affects postmenopausal women in their sixth or seventh decade of life. We report a case of a 52-year-old female who presented to our clinic with concerns about a self-palpable mass involving her left breast that had not been detected on a routine mammogram five months prior. Upon clinical exam and diagnostic workup comprising imaging, a tissue biopsy, and immunostaining, she was found to have primary high-grade neuroendocrine carcinoma of the breast with necrosis. Subsequently, management of her case involved a first-line systemic chemotherapy regimen, including carboplatin with etoposide and atezolizumab. Less than two months after beginning therapy, she had undergone three cycles but did not show any significant clinical response, requiring further workup. This case demonstrates the challenges faced with treating such a rare subtype of breast carcinoma and the necessity of documenting other similar cases for improved understanding and patient outcomes.