NET Flashcards
What is a neuroendocrine tumor?
Epithelial neoplasm with predominantly neuroendocrine differentiation arising from enterochromaffin cells
What is carcinoid syndrome?
Vasoactive substances release by tumour escaping hepatic degradation
What is the cellular morphology of NET?
- coarsely stippled chromatin (salt and pepper)
- organoid arrangement of tumor cells
- round /oval nuclei
- finely granular cytoplasm
What are immunohistochemical features of NET?
- abundant chromogranin and synaptophysin
What are features of carcinoid syndrome?
- Flushing
- Watery diarrhea
- Bronchospasm
- Fibrotic valvular heart disease
Types of functional NET
- Gastrinoma (Zollinger-Ellison Syndrome)
- Insulinoma
- Glucagonoma
- Somatostatinoma
- VIPoma (Verner-Morrison syndrome)
Clinical presentation for insulinoma
Whipple triad
- Symptoms caused by hypoglycemia
- Low blood glucose
- Relief of symptoms when glucose replenished
Clinical presentation of Gastrinoma
Zollinger-Ellison’s syndrome
- Peptic ulcers
- Diarrhea
Clinical symptoms of VIPOMA
- Watery diarrhea
- Hypokalemia
- Hypochlorhydria
Clinical symptoms of glucagonoma
- Diabetes glucose intolerance
- Weight loss
- Rash (necrolytic migratory erythema)
- Chronic diarrhea
- Venous thrombosis
Principles of management for patient suspected of PNET
- Determine functionality and localized vs metastatic
- Determine resectability
- Definitive management
Management of functional PNET
Resection or enucleation
Workup for GI NET
- Blood: chromogranin A, CEA
- Urinary 5HIAA if carcinoid symptoms
- Imaging:
- Contrast CT A+P: hypervascular lesion
- DOTATATE/DOTATOC PET-CT
- Histology: EUS +/- bx/FNAC, TRUS +/- bx
- Colonoscopy
What type of NET produce highest levels of serotonin?
Midgut:
- Jejunoileal
- Appendiceal
- Ascending colon
Chromogranin A
- Tumour biomarker to assess disease progression and response to therapy
- Low specificity, therefore not diagnostic
Significance of Urinary 5HIAA
Diagnostic test for carcinoid syndrome
How are carcinoid tumors classified?
- By site of origin: foregut/midgut/hindgut
- Degree of differentiation: well-differentiated/ poorly/ mixed endo-exocrine
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What is the gastroenteropancreatic NET classification based on?
- Histological appearance
- Mitotic index (# of mitoses per 10 HPF)
- Ki67 proliferation index
Treatment for Gastric NET
- Depends on size:
- <1cm: endoscopic resection
- >1cm
- LN+ → radical gastrectomy
- multiple lesions → gastrectomy
- single lesion → endoscopic resection
- >2cm: workup with DOTATOC + FDG PET-CT
- Localized → radical gastrectomy
- Metastatic→ systemic treatment
Treatment for Pancreatic NET
- Functional PNET → resection
- Non-functional PNET
- LN+ve → pancreatectomy + lymphadenectomy
- <2cm: surveillance if G1, asymptomatic
- >2cm: enucleation / limited resection / pancreatectomy (if close to PD)
- Metastatic disease
- Resectable → pancreatectomy + lymphadenectomy + metastectomy
- Unresectable → systemic therapy
Criteria for surveillance in non-functional PNET
- <2cm
- LN -ve
- Consider following
- G1
- Asymptomatic
- Poor patient factors
Management of appendiceal NET
- Localized disease?
- <1cm. with no risk factors → appendectomy alone
- 1-2cm with no risk factors→ Appendectomy alone
- >2cm: right hemicolectomy
- Metastatic disease?
- Resectable?
- Yes: Right Hemi + Metastectomy
- No: Systemic treatment
- Resectable?
High risk factors in appendiceal NET
- G2 or above
- Margin involvement
- LN+ve
- Lymphovascular invasion
- Mesoappendiceal invasion > 3mm
- Base of appendix or cecal involvement
- Mixed histology (goblet cell adeno)
NET Grade 1
- mitotic count <2
- Ki67 < 3 %
