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E-Cadherin–Negative Primary Small Cell Carcinoma of the Breast
Report of a Case and Review of the Literature

Simon Bergman MD, Syed A. Hoda MD, Kim R. Geisinger MD, Andrew J. Creager MD, Jacqueline K. Trupiano MD
DOI: http://dx.doi.org/10.1309/737Y07JNP8GQQJJY 117-121 First published online: 1 January 2004


Primary small cell carcinoma of the breast is exceedingly rare, with fewer than 25 reported cases. The case presented herein is that of a 61-year-old woman with a 2.5-cm mass of the left breast. She underwent mastectomy with axillary node dissection. Histologic examination revealed sheets and nests of small, hyperchromatic, malignant cells with indistinct nucleoli and scant cytoplasm. High-grade solid and comedo ductal carcinoma in situ also was present. Two of 5 axillary lymph nodes contained metastatic disease. Immunohistochemical analysis demonstrated weak immunoreactivity for cytokeratin, neuron-specific enolase, and bcl-2. This histologic and immunohistochemical profile was consistent with that of a primary small cell carcinoma. Interestingly, this neoplasm lacked immunoreactivity for E-cadherin. E-cadherin expression has been documented in all 11 (100%) of 11 previously reported cases of primary small cell carcinoma of the breast, suggesting that this tumor is a form of ductal carcinoma. To our knowledge, this is the first reported case of E-cadherin–negative small cell carcinoma of the breast, which raises the question of a possible lobular histogenesis in some of these neoplasms.

Key Words:
  • Small cell carcinoma
  • Breast
  • E-cadherin