BREAST CYTOPATHOLOGY

Special Types of Breast Carcinomas 129
• This group of tumors is similar to neuroendocrine tumors
of the lung and the gastrointestinal tract.
• Metastatic neuroendocrine carcinomas are more common
than primary breast tumors of the same type, and lung is
the most common source.
• Infiltrating breast carcinomas NOS may have focal endocrine
differentiation and are not included in this group of
primary neuroendocrine carcinomas.
Cytomorphologic Characteristics (Figure 4.48)
• Hypercellular
• Small round blue cells, uniformly lacking pleomorphism,
arranged in a loosely cohesive fashion
• Nuclear molding, hyperchromasia, inconspicuous nucleoli,
fine powdery chromatin, karyorrhexis, mitoses, and often
nuclear crush artifact
• Cytopathologic distinction between primary and metastatic
neuroendocrine carcinoma not possible on the aspirate
Figure 4.48. Neuroendocrine carcinoma. Hypercellular smear with
singly dispersed carcinoma cells with high nucleus to cytoplasm
ratios, nuclear hyperchromasia, and finely dispersed chromatin.
Note the lymphocytelike morphology on Diff-Quik staining (left).
Also evident is nuclear crush artifact and numerous karyorrhectic
nuclei (right). (Smear, Diff-Quik and Papanicolaou, Diff-Quik.)