Characteristic | Features |
---|---|
Epidemiologic | Â |
Age of diagnosis (years) | >50 |
Sex | Female>Male |
Physical examination | Â |
Clinical presentation | Single palpable, well-circumscribed nodule (xÌ…: 2.5cm) or nipple discharge. |
Nodal status | Non-palpable axillary lymph nodes |
Carcinoid symptoms | Absent |
Histopathology | Â |
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) |