No evidence for a causal role of Merkel cell polyomavirus in keratoacanthoma

J Am Acad Dermatol. 2012 Jul;67(1):41-6. doi: 10.1016/j.jaad.2011.07.026. Epub 2011 Oct 11.


Background: Merkel cell polyomavirus (MCPyV) is a recently discovered virus that is monoclonally integrated into the genome of approximately 80% of all Merkel cell carcinomas (MCCs). While some evidence exists that MCPyV does not play a pathogenic role in other nonmelanoma skin cancers, such as basal cell carcinoma and squamous cell carcinoma (SCC), little is known about the presence of MCPyV in keratoacanthoma (KA).

Objectives: To evaluate the prevalence, viral DNA-load, and large T(umor)-antigen expression of MCPyV in KA of immunocompetent patients and to compare the results with those found in SCC and MCC.

Methods: Paraffin-embedded tissue samples were analyzed for the presence of MCPyV-DNA by polymerase chain reaction (PCR). MCPyV-DNA load (MCPyV-DNA copies per beta-globin gene copy) was determined by using quantitative real-time PCR. Immunohistochemical analysis of the MCPyV large T-antigen was performed with the monoclonal antibody CM2B4.

Results: A total of 137 samples (42 KA, 52 SCC, and 43 MCC) were analyzed. MCPyV-DNA was found significantly more frequently in MCC (37/43, 86.0%) compared with KA (12/42, 28.6%) and SCC (14/52, 26.9%). Moreover, MCPyV-DNA loads were more than two orders of magnitude lower in KA and SCC compared with MCC (median/mean loads 0.005/0.015 [KA] vs 0.023/0.059 [SCC] vs 2.613/56.840 [MCC] MCPyV-DNA copies per beta-globin gene copy). All MCC analyzed (n = 3) expressed MCPyV large T-antigen, whereas 8 KA and 7 SCC were negative in immunohistochemistry.

Limitations: The relatively small number of samples is a limitation.

Conclusions: Our findings argue against a pathogenic role of MCPyV in KA and SCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antigens, Viral, Tumor / analysis
  • Carcinoma, Merkel Cell / virology*
  • Carcinoma, Squamous Cell / virology
  • DNA, Viral / analysis
  • Female
  • Humans
  • Keratoacanthoma / virology*
  • Male
  • Merkel cell polyomavirus / immunology
  • Merkel cell polyomavirus / isolation & purification*
  • Middle Aged
  • Skin Neoplasms / virology*
  • Viral Load


  • Antigens, Viral, Tumor
  • DNA, Viral