Neuroendocrine neoplasms

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Neuroendocrine neoplasms, also neuroendocrine tumours, are a group of tumours whose behaviour varies from benign to malignant and are found in may different sites.

These tumours arise from epithelium; thus, malignant tumours in this group are referred to as neuroendocrine carcinomas.

Use of the term carcinoid

Use of the term carcinoid is discouraged (in pathology reports), in the context of gastrointestinal pathology.[1][2][3]

The term is still used for neuroendocrine tumours of the lung - see carcinoid tumours.

Carcinoid syndrome

Pathophysiology

  • Neuroendocrine tumour -> hormone secretion (5-hydroxytryptamine + others).[4]

Clinical

Features:[4]

  • Diarrhea, flushing and wheezing.

Pathologic findings

Classic pathologic finding:[4]

  • Fibrosis of cardiac valves (tricuspid and pulmonary).
    • Result TIPS = tricuspid insufficiency pulmonary stenosis.

Microscopic - generic

Features:

  • Nests of cells - with fibrous stroma in between.
  • Stippled chromatin AKA salt-and-pepper chromatin, coarse chromatin.
  • Classically subepithelial/mural.

DDx:

Images:

IHC - generic

Key stains:[6]

  • Chromogranin A +ve.
    • Considered the most specific neuroendocrine stain.[7]
  • Synaptophysin +ve.

Others:

  • NSE +ve.
  • CD56 +ve.
  • Ki-67 - useful for grading.
  • PGP9.5.[7]

Hormone products:

  • Glucagon +ve/-ve.
  • Gastrin +ve/-ve.
  • Somatostatin +ve/-ve.

Site specific

Lung

Gastrointestinal tract

WHO classification for digestive NET

Subtypes:[8]

  1. Neuroendocrine tumour G1.
  2. Neuroendocrine tumour G2.
  3. Neuroendocrine carcinoma, small cell type.
  4. Neuroendocrine carcinoma, large cell type.
  5. Mixed adenoneuroendocrine carcinoma.

Grading

Grading of NETs:[9]

  • Grade 1 (G1): < 2 mitoses/2 mm^2 or < 3% Ki-67.
  • Grade 2 (G2): > 2 mitoses/2 mm^2 or > 3% Ki-67 and < 20 mitoses/2 mm^2 or < 20% Ki-67.
  • Grade 3 (G3): > 20 mitoses/2 mm^2 or > 20% Ki-67.

Notes:

  • Neuroendocrine carcinomas are G3 by definition.

Stomach

Divided into four types:[10]

Tumour type Relative prevalence Multifocality Tumour size Typical location Clinical Other Histology
Type 1 ~75% yes small (5-10 mm) body benign typically, female:male ~ 4:1, 50-60 years chronic atrophic gastritis - usu. autoimmune WDNET, WDNEC
Type 2 rare yes small ~15 mm body aggressive, ~50 years old assoc. MEN I, hyperchlorhydia WDNEC, WDNET
Type 3 10-15% no small and large variable location aggressive if >2.0 cm, males > females normal gastrin levels WDNET
Type 4 extremely rare no large variable location aggressive (mets usu. at time of Dx), males > females elevated gastrin d/t parietal cell dysfunction PDNEC

Notes:

  • WDNET = well-differentiated neuroendocrine tumour.
  • WDNEC = well-differentiated neuroendocrine carcinoma.
  • PDNEC = poorly-differentiated neuroendocrine carinoma.

Duodenum

Pancreatic

Vermiform appendix

See also

References

  1. Chetty, R. (Apr 2008). "Requiem for the term 'carcinoid tumour' in the gastrointestinal tract?". Can J Gastroenterol 22 (4): 357-8. PMID 18414708.
  2. Klöppel, G.; Perren, A.; Heitz, PU. (Apr 2004). "The gastroenteropancreatic neuroendocrine cell system and its tumors: the WHO classification.". Ann N Y Acad Sci 1014: 13-27. PMID 15153416.
  3. Klöppel G (July 2003). "[Neuroendocrine tumors of the gastrointestinal tract]" (in German). Pathologe 24 (4): 287–96. doi:10.1007/s00292-003-0636-7. PMID 14513276.
  4. 4.0 4.1 4.2 Druce, M.; Rockall, A.; Grossman, AB. (May 2009). "Fibrosis and carcinoid syndrome: from causation to future therapy.". Nat Rev Endocrinol 5 (5): 276-83. doi:10.1038/nrendo.2009.51. PMID 19444261.
  5. URL: [http://path.upmc.edu/cases/case7.html http://path.upmc.edu/cases/case7.html}. Accessed on: 17 December 2011.
  6. Williams, GT. (Jan 2007). "Endocrine tumours of the gastrointestinal tract-selected topics.". Histopathology 50 (1): 30-41. doi:10.1111/j.1365-2559.2006.02570.x. PMID 17204019.
  7. 7.0 7.1 McCluggage, WG.; Kennedy, K.; Busam, KJ. (Apr 2010). "An immunohistochemical study of cervical neuroendocrine carcinomas: Neoplasms that are commonly TTF1 positive and which may express CK20 and P63.". Am J Surg Pathol 34 (4): 525-32. doi:10.1097/PAS.0b013e3181d1d457. PMID 20182342.
  8. Scoazec, JY.; Couvelard, A. (Apr 2011). "[The new WHO classification of digestive neuroendocrine tumors].". Ann Pathol 31 (2): 88-92. doi:10.1016/j.annpat.2011.01.001. PMID 21601112.
  9. Volante, M.; Righi, L.; Berruti, A.; Rindi, G.; Papotti, M. (Apr 2011). "The pathological diagnosis of neuroendocrine tumors: common questions and tentative answers.". Virchows Arch 458 (4): 393-402. doi:10.1007/s00428-011-1060-7. PMID 21344263.
  10. URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/StomachNET_11protocol.pdf. Accessed on: 29 March 2012.