Primary neuroendocrine tumor of the breast - report of 2 cases

  • László Fónyad 1st Department of Pathology and Experimental Cancer Research, Semmelweis University
  • László Piros Department of Transplantation and Surgery, Semmelweis University
  • Gabriella Arató 1st Department of Pathology and Experimental Cancer Research, Semmelweis University
  • Janina Kulka 2nd Department of Pathology, Semmelweis University


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Background: Primary neuroendocrine tumor of the breast is rare, although 20-30% of primary breast carcinomas show neuroendocrine differentiation to some degree. According to the 2012 WHO Classification of Tumours of the Breast the current classification recognizes 3 subgroups of breast tumors with neuroendocrine features: Neuroendocrine tumor, well-differentiated; Neuroendocrine tumor, poorly-differentiated; Invasive breast carcinoma with neuroendocrine differentiation. Due to the low prevalence of this disease our understanding of its development, prognosis and effective therapy is limited. Up to date there are approximately 125 cases reported in the English and non-English literature. Here we report two further cases.
Material-Methods Our first patient was 63 years old and presented with a 3 cm large mobile nodule in the upper outer quadrant of her right breast. After a complete clinicopathological work-up of imaging techniques and core needle biopsy with an initial diagnosis of invasive carcinoma of no special type (IBC NST), lumpectomy and sentinel node biopsy was recommended by the institutional tumor board. The second patient was 75 years old and presented with a 2 cm large mobile nodule in the upper outer quadrant of her left breast. Lumpectomy was performed based on fine needle aspiration cytology results that revealed the malignant proliferation.
Results: Histological examination of the surgical specimens revealed neuroendocrine differentiation in approximately 90% of the tumor cells in both cases. Immunohistochemical studies and additional imaging studies disclosed the possibility of metastasis to the breast.
Disscussion: Neuroendocrine differentiation of breast tumors is a controversial issue and there are numerous questions in terms of histogenesis, diagnostics and clinical considerations. To establish the correct diagnosis, characteristic growth patterns and cytological and immunohistochemical features of neuroendocrine differentiation should be carefully evaluated.


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How to Cite
FóNYAD, László et al. Primary neuroendocrine tumor of the breast - report of 2 cases. Diagnostic Pathology, [S.l.], v. 4, n. 1, mar. 2018. ISSN 2364-4893. Available at: <>. Date accessed: 05 feb. 2023. doi:
Case Report