Appendix
Other tumors
L cell carcinoid tumor (tubular carcinoid)


Topic Completed: 01 August 2012

Revised: 23 January 2019

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PubMed Search: Tubular carcinoid appendix
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Cite this page: Mansouri J. L cell carcinoid tumor (tubular carcinoid). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/appendixLcellcarcinoid.html. Accessed January 23rd, 2019.
Definition / general
Gross description
  • Small nodules at tip, often not identified grossly
Microscopic (histologic) description
  • Columns, ribbons, acini or small tubules of small round cells with pale eosinophilic cytoplasm and round/oval nuclei with small nucleoli
  • No/rare mitotic activity
  • No insular masses
  • May have dominant glandular, infiltrative pattern resembling metastatic carcinoma
Microscopic (histologic) images

Images hosted on other servers:

Left: typical carcinoid (insular pattern); right: L cell carcinoid (tubular carcinoid)

Positive stains
  • Chromogranin B, synaptophysin, CEA, glucagon, peptide YY, pancreatic polypeptide
Negative stains
  • Mucin, chromogranin A (usually)
Differential diagnosis
  • Well differentiated metastatic adenocarcinoma: CK7/CK20 staining is nonspecific and represents potential diagnostic pitfall (J Clin Pathol 2012;65:666)