Primary neuroendocrine carcinoma of the breast in association with squamous cell carcinoma of the breast: A case report and review of the literature

Squamous cell carcinoma associated with primary neuroendocrine carcinoma (NEC) of the breast, also known as composite tumor, is an extremely rare malignancy with a very poor prognosis. We report the case of a patient treated in our department for primary neuroendocrine carcinoma of the breast associated with squamous cell carcinoma by radical surgery. Diagnosis is based on histology and, above all, immunohistochemistry. Management depends on the primary or secondary origin of the neuroendocrine component, which constitutes the prognostic element. Squamous cell carcinoma associated with neuroendocrine carcinoma of the breast is an aggressive tumor. Due to its rarity, it is difficult to diagnose and to determine the most appropriate therapeutic protocol. •Squamous cell carcinoma associated with neuroendocrine carcinoma (NEC) of the breast is an extremely rare malignancy with a poor prognosis.•Diagnosis is based on histology and, above all, immunohistochemistry of the surgical specimen or sufficient biopsy fragments.•The neuroendocrine component dominates the clinical presentation and conditions prognosis through the frequency of secondary localizations.