Poorly differentiated neuroendocrine carcinoma of the breast with Merkel cell features

Neuroendocrine carcinoma of the breast is a rare tumor subtype comprising less than 1% of breast cancers in the United States. Merkel cell features within this rare subtype are even rarer. We report a neuroendocrine breast carcinoma with Merkel cell features. The patient underwent breast conservation therapy and a sentinel lymph node biopsy. Unfortunately, the tumor was extremely aggressive and at 5 weeks postoperatively she presented with widely metastatic disease. Due to the aggressive nature of this tumor, we reviewed the literature and treatment options for this rare variant of a rare subtype.