Cytokeratin-20 negative nodal Merkel cell carcinoma with regressed primary: a potential pitfall in interpretation of nodal metastasis

Dermatol Online J. 2023 Jun 15;29(3). doi: 10.5070/D329361428.

Abstract

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous neuroendocrine carcinoma that affects sun-damaged skin. Histologically, the tumor consists of round cells with fine chromatin positive for cytokeratin 20 in ~90% of cases. Rare cases of MCC can regress spontaneously and present as nodal metastasis. Nodal MCC of unknown primary can cause a potential pitfall as they can be misinterpreted as other neuroendocrine carcinomas such as small cell carcinoma. We report a case of nodal MCC with an atypical immunohistochemistry pattern presented as bilateral axillary lymphadenopathy in a 90-year-old man with a remote history of a skin lesion that healed spontaneously leaving a scar.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Carcinoma, Merkel Cell* / diagnosis
  • Carcinoma, Neuroendocrine*
  • Cicatrix
  • Humans
  • Keratin-20
  • Male
  • Skin Neoplasms*

Substances

  • Keratin-20