Objective:

To report a case of primary triple-negative neuroendocrine breast carcinoma (NEBC) and explore the role of pembrolizumab combined with chemotherapy in its treatment, particularly in the context of existing treatment options.

Key Findings:

• The patient was diagnosed with primary NEBC, confirmed through histopathology and immunohistochemistry, including PD-L1 positivity.
• The treatment regimen of chemotherapy and pembrolizumab was well tolerated with only grade 1–2 toxicities.
• At 12-month follow-up, the patient remained disease-free with no evidence of recurrence.

Interpretation:

This case provides preliminary evidence for the use of chemo-immunotherapy in treating primary triple-negative NEBC, a rare and aggressive subtype, highlighting the need for further research.

Limitations:

• The study is based on a single case report, limiting generalizability and introducing potential biases.
• Lack of standardized treatment guidelines for NEBC complicates comparisons with other breast cancer subtypes.

Conclusion:

This case highlights the potential of combining adjuvant chemotherapy with pembrolizumab in managing primary triple-negative NEBC, warranting further investigation to validate these findings.