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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





Age of diagnosis (years)




Physical examination


Clinical presentation

Single palpable, well-circumscribed nodule (x̅: 2.5cm) or nipple discharge.

Nodal status

Non-palpable axillary lymph nodes

Carcinoid symptoms




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


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)


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.