Primary breast carcinomas with neuroendocrine features: Clinicopathological features and analysis of tumor growth patterns in 36 cases

Ann Diagn Pathol. 2018 Jun:34:122-130. doi: 10.1016/j.anndiagpath.2018.03.010. Epub 2018 Apr 4.

Abstract

Primary breast carcinoma with neuroendocrine features (NEBC) is an uncommon tumor. In the classification of WHO 2012, these tumors were categorized as: 1- neuroendocrine tumor, well-differentiated; 2- neuroendocrine carcinoma, poorly differentiated/small cell carcinoma; and 3- invasive breast carcinoma with neuroendocrine differentiation. In this study, we reviewed NEBC except poorly differentiated/small cell carcinoma variant in order to define the morphological growth patterns and cytonuclear details of these tumors. All breast surgical excision materials between 2007 and 2016 were re-evaluated in terms of neuroendocrine differentiation. Thirty-six cases showing positive staining for synaptophysin and/or chromogranin A in ≥50% of tumor cells were included in the study. All cases were female with a mean age of 67.4. Mean tumor diameter was 26 mm. Multifocality was noted in 5 cases. Grossly, they were mostly infiltrative mass lesions. T stages, identified in 34 cases, were as follows: 13 cases with pT1; 19 pT2 and 2 pT3. We described schematically 4 types of patterns depending on predominant growth pattern, except one case: 1) Large-sized solid cohesive groups (6 cases), 2) Small- to medium-sized solid cohesive groups with trabeculae/ribbons and glandular structures (6 cases), 3) Mixed growth patterns (20 cases), 4) Invasive tumor with prominent extracellular and/or intracellular mucin (3 cases). The tumor cells were mostly polygonal-oval with eosinophilic/eosinophilic-granular cytoplasm. The nuclei of tumor cells were mostly round to oval with evenly distributed chromatin. Only 5 cases showed high grade nuclear and histological features. Molecular subtypes of the cases were as follows: 33 luminal A, 2 luminal B, and 1 triple negative. NEBC should come to mind when a tumor display one of the morphological patterns described above, composed of monotonous cells with mild to moderate nuclear pleomorphism and abundant eosinophilic/eosinophilic granular or clear cytoplasm, especially in elderly patients.

Keywords: Breast; Neuroendocrine carcinoma.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Breast / pathology
  • Breast Neoplasms / pathology*
  • Carcinoma, Neuroendocrine / pathology*
  • Cell Nucleus / pathology
  • Chromogranin A / metabolism
  • Female
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Neuroendocrine Tumors / pathology*
  • Synaptophysin / metabolism

Substances

  • Chromogranin A
  • Synaptophysin