Low Grade Neuroendocrine Carcinoma of the Breast
Definition
- Low grade breast carcinoma expressing predominant neuroendocrine differentiation
Alternate / historical names
- Carcinoid
- Endocrine carcinoma
- Spindle cell endocrine carcinoma
Diagnostic Criteria
- Diagnosis requires all of the following four criteria
- At least 50% of cells are neuroendocrine marker positive
- Most cases positive for chromogranin and/or synaptophysin
- Neuron specific enolase is not sufficiently specific for this diagnosis
- Lesser numbers of positive cells are seen in usual type breast carcinomas
- Growth in solid sheets or insular pattern
- Peripheral palisading common
- Stippled chromatin
- Low grade cytologic features
- Round, regular to mildly irregular nuclei up to 2-3x the size of a RBC
- No comedo necrosis
- At least 50% of cells are neuroendocrine marker positive
- Extracellular mucin is common
- May merge with mucinous carcinoma
- Frequently associated with endocrine DCIS
- Spindle cell variant
- Above criteria required
- Predominantly composed of spindle cells
- Subset of cells may be cuboidal and form glands
- Reported cases all low grade
- High grade neuroendocrine carcinoma and neuroendocrine carcinoma NOS are considered separately
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: May 1, 2006