Immunohistochemical distinction between Merkel cell carcinoma and small cell carcinoma of the lung

Mattheos Bobos, Prodromos Hytiroglou, Ioannis Kostopoulos, Georgios Karkavelas, Constantine S. Papadimitriou

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195 Scopus citations


We assessed the usefulness of several immunohistochemical stains in distinguishing these two neoplasms, including cytokeratin 7, cytokeratin 20 (CK20), neuron-specific enolase, chromogranin, synaptophysin, neurofilaments (NF), thyroid-transcription factor-1 (TTF-1), CD56 antigen, S-100 protein, vimentin, c-erbB-2 oncoprotein, and CD117 antigen. All 13 cases of Merkel cell carcinoma evaluated were positive for CK20, and negative for TTF-1. Twelve of 13 Merkel cell carcinoma cases were positive for NF. Eleven of 13 cases of small cell lung carcinoma were positive for TTF-1. All small cell lung carcinoma cases were negative for NF, and all but one were negative for CK20. In terms of the remaining antigens, there were no differences of significance between the two neoplasms. These findings suggest that a set of three immunohistochemical stains, including CK20, NF, and TTF-1, is useful in affording a distinction between Merkel cell carcinoma and small cell lung carcinoma.

Original languageEnglish
Pages (from-to)99-104
Number of pages6
JournalAmerican Journal of Dermatopathology
Issue number2
StatePublished - Apr 2006
Externally publishedYes


  • Cytokeratin 20
  • Merkel cell carcinoma
  • Neurofilaments
  • Small cell lung carcinoma
  • Thyroid transcription factor-1


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