Stains & CD markers
Carcinoma of unknown primary

Last author update: 1 November 2013
Last staff update: 26 February 2024 (update in progress)

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PubMed Search: tissue of origin[title]

Nat Pernick, M.D.
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Cite this page: Pernick N. Carcinoma of unknown primary. website. Accessed April 14th, 2024.
Definition / general
Recommended IHC markers
  • Epithelial markers: low molecular weight keratin (CAM 5.2), AE1-AE3 cytokeratin cocktail, CK7, CK20, CEA and EMA
  • Alternative epithelial markers on sarcomatoid carcinoma include p63, MOC-31 and TTF1 (Mod Pathol 2005;18:1471)

  • Melanocytic markers: S100 (also a mesenchymal marker), HMB45, MelanA / Mart1

  • Lymphoid markers: CD3 (T cells), CD20 (B cells), CD15 (Hodgkin), CD30 (Hodgkin & other) and various others

  • Histiocytic markers: CD68, lysozyme, CD1a (Langerhans cells)

  • Neuroendocrine markers: neuron specific enolase, chromogranin, synaptophysin, CD56 and CD57

  • Mesenchymal markers: vimentin (non-specific), factor XIIIa (fibrous histiocytoma), factor VIII (vessels), CD31 (vessels), CD34 (vessels), D2-40 (lymphatics), HHF35 (actin), smooth muscle actin and desmin

  • Cell proliferation / apoptosis markers: Ki-67, bcl2
Microscopic (histologic) images

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Classification examples

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