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Table 2 Representative clinical and histopathological features of primary neuroendocrine carcinoma of the breast

From: Locally-advanced primary neuroendocrine carcinoma of the breast: case report and review of the literature

Characteristic Features
Epidemiologic  
Age of diagnosis (years) >50
Sex Female>Male
Physical examination  
Clinical presentation Single palpable, well-circumscribed nodule (x̅: 2.5cm) or nipple discharge.
Nodal status Non-palpable axillary lymph nodes
Carcinoid symptoms Absent
Histopathology  
Tumor components Co-existing neuroendocrine and ductal cancer cell populations possibly from divergent differentiation of cancer stem cells (lobular or other types of breast cancer are rare).
Multifocality or multicentricity Rare
Growth pattern Solid carcinoid-like (most common), large cell-type, and small/oat cell-type
Cell type Homogenous group of plasmacitoid, signet ring, clear cell, or small/oat cells
Histopathological features Nuclear palisading; pseudorosette formation; loss of cell cohesion; intra- and/or extra-cellular mucin content; and abundant eosinophilic cytoplasm and nuclei with stippled (‘salt and pepper’) chromatin.
Diagnostic markers Most sensitive and specific: chromogranin A or B and synaptophysin.
Least specific: neurospecific enolase, CD56, neurofilament triplprotein, and bombin or leu.
Hormonal receptors Estrogen/progesterone receptor positive
HER2 negative
Molecular subgroup Luminal A (basal-type has been documented)
Staging, TisN0M0: 9 (10.9)
n (%) (N=82)a T1NxM0: 35 (42.7)
T2NxM0: 27 (32.9)
T3NxM0: 8 (9.8)
  T4NxM0: 3 (3.7)
  1. a Based on case reports that specified size of the lesion; includes present case.