Appendix
Other tumors
L-cell carcinoid tumor (tubular carcinoid)

Reviewer: Jaleh Mansouri, M.D. (see Authors page)

Revised: 1 March 2016, last major update August 2012

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Tubular carcinoid appendix
General
  • See also carcinoid and goblet cell carcinoid

  • Carcinoid tumor, much less common than classic tumors with insular pattern (EC-cell tumors); cell of origin is usually the L-cell, which produces enteroglucagons and peptide YY (Arch Pathol Lab Med 2010;134:1612)
  • Minimal metastatic potential
  • Gross Description
  • Small nodules at tip, often not identified grossly
  • Micro 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
  • Micro 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)