Merkel cell carcinoma with heterologous rhabdomyoblastic differentiation: the role of immunohistochemistry for Merkel cell polyomavirus large T-antigen in confirmation

J Cutan Pathol. 2012 Jan;39(1):47-51. doi: 10.1111/j.1600-0560.2011.01794.x. Epub 2011 Oct 28.


Merkel cell carcinoma (MCC) represents an uncommon and lethal form of cutaneous malignancy. Historically, the pathogenesis of MCC has been presumed to be linked to ultraviolet light overexposure, but recently, it has been documented that some examples harbor polyomavirus genome, the presence of which is presumed to be of pathogenetic importance. Extremely rare cases of MCC may show heterologous differentiation. We report an example of MCC with heterologous rhabdomyosarcomatous differentiation, the third such case to date, with emphasis on its distinction from fusion-negative alveolar rhabdomyosarcoma. The role of immunohistochemistry for Merkel cell polyomavirus large T-antigen in this differential diagnosis is emphasized.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Antigens, Viral, Tumor / metabolism*
  • Biomarkers, Tumor / metabolism*
  • Carcinoma, Merkel Cell* / metabolism
  • Carcinoma, Merkel Cell* / pathology
  • Carcinoma, Merkel Cell* / therapy
  • Carcinoma, Merkel Cell* / virology
  • Cell Differentiation*
  • Diagnosis, Differential
  • Eyelid Neoplasms* / metabolism
  • Eyelid Neoplasms* / pathology
  • Eyelid Neoplasms* / therapy
  • Eyelid Neoplasms* / virology
  • Female
  • Humans
  • Merkel cell polyomavirus / metabolism*
  • Polyomavirus Infections* / metabolism
  • Polyomavirus Infections* / pathology
  • Polyomavirus Infections* / therapy
  • Rhabdomyosarcoma, Alveolar* / metabolism
  • Rhabdomyosarcoma, Alveolar* / pathology
  • Rhabdomyosarcoma, Alveolar* / therapy
  • Rhabdomyosarcoma, Alveolar* / virology
  • Tumor Virus Infections* / metabolism
  • Tumor Virus Infections* / pathology
  • Tumor Virus Infections* / therapy


  • Antigens, Viral, Tumor
  • Biomarkers, Tumor