Neuroendocrine Neoplasms of the Ampullary
Region
Epidemiology and Etiology:
Common sites:
Gross features:
Histologic features:
- Grading as per other foregut neuroendocrine tumours
- Well-differentiated neuroendocrine tumours (NETs) (low-to intermediate-grade):
- Nested, trabecular, or cribriform growth
pattern (most)
- Uniform neoplastic cells
- Moderate amounts of cytoplasm
- Round nuclei with “salt and pepper” chromatin
- Mitoses usualy rare
(<2 per 10 HPF) (grading as per other GI NETs)
- Somatostatin-producing NET:
- Tubuloglandular structures predominantly
- May cause confusion with well-differentiated
adenocarcinoma
- Admixed with a variable proportion of insular
and trabecular structures (“glandular carcinoids”)
- Psammoma bodies contained in glands (~1/3)
- Uniform cells with bland nuclei
- Few mitotic figures
- Distinct finely granular eosinophilic
cytoplasm
- May be confused with normal Brunner glands
when cytoplasm is abundant
- Gangliocytic
paraganglioma:
- Poorly-differentiated (high-grade)
neuroendocrine carcinomas (NECs):
- Diffuse, solid and/or trabecular growth pattern
- Areas of necrosis
- High mitotic rate (>20 / 10 HPF)
- High proliferative index (30-80%)
- Small cell carcinoma:
- Large cell NEC:
- Resembling large cell NEC of the lung
- Minor component (< 30%) of conventional
adenocarcinoma may be associated
- Associated adenoma in the adjacent mucosa of
the papilla (maybe)
- Mixed adenoneuroendocrine
carcinoma (MANEC)
- Exocrine and neuroendocrine components, each
component exceeds 30%
- Mucin-producing adenocarcinoma component
- Rarely squamous cell carcinoma component
- Two components may be adjacent or intermingled
Immunophenotype:
|
Marker:
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Sensitivity:
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Specificity:
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CK7, 8,
18
|
|
|
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Synaptophysin
|
|
|
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Chromogranin A
|
Maybe
|
|
|
CD56
|
Maybe
|
|
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P53
|
Occasionally
|
|
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CDKN1B/p27/Kip1
|
Occasionally
|
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Molecular features:
Other features:
- Staging as per other foregut neuroendocrine tumours
References:
- Bosman FT, Carneiro F,
Hruban RH, Theise ND
(eds.) WHO Classification of Tumours of the Digestive System (2010)
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